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The number of gluons in the hadron wave function is discrete, and their formation in the chain of small $x$ evolution occurs over discrete rapidity intervals of $\Delta y \simeq 1/\as$. We therefore consider the evolution as a discrete quantum process. We show that the discrete version of the mean-field Kovchegov evolution equation gives rise to strong fluctuations in the scattering amplitude, not present in the continuous equation. We find that if the linear evolution is as fast as predicted by the perturbative BFKL dynamics, the scattering amplitude at high energies exhibits a chaotic behavior. As a consequence, the properties of diffraction at high energies become universal.
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arxiv:hep-ph/0501271
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We review the proposal that trans-GZK cosmic ray interactions are caused by neutrino primaries. The primaries cause excitations of strings and give rise to extensive air showers (EAS) resembling EAS induced by nuclei. We also show that in ``low scale'' string models (of characteristic energy about 70TeV) the excited string and the mini black hole pictures are equivalent.
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arxiv:hep-ph/0501280
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The axino and the gravitino are well-motivated candidates for the lightest supersymmetric particle (LSP) and also for cold dark matter in the Universe. Assuming that a charged slepton is the next-to-lightest supersymmetric particle (NLSP), we show how the NLSP decays can be used to probe the axino LSP scenario in hadronic axion models as well as the gravitino LSP scenario at the Large Hadron Collider and the International Linear Collider. We show how one can identify experimentally the scenario realized in nature. In the case of the axino LSP, the NLSP decays will allow one to estimate the value of the axino mass and the Peccei-Quinn scale.
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arxiv:hep-ph/0501287
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New preliminary combined results from the LEP experiments on searches for the Higgs boson beyond the Standard Model are presented. The new determination of the top quark mass at the Tevatron in 2004 influences the interpretations of the LEP results in both, the Standard Model, and the Minimal Supersymmetric extension of the Standard Model. Higgs boson physics will also be a major research area at the future Linear Collider. A review including new preliminary results on the potential for precision measurements is given.
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arxiv:hep-ph/0502002
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The structure of the pentaquark baryon $\Theta^+$ is discussed in terms of a $K^+$-skyrmion binding where the skyrmion arises as a soliton in hidden local symmetry approach to low-energy hadronic physics which may be considered as a holographic dual to QCD. The "vector manifestation" of chiral symmetry encoded in the effective theory Wilsonian-matched to QCD is proposed to play an important role in the binding. Among the options available for understanding the pentaquark structure is the intriguing possibility that the $\Theta^+$ is a Feshbach resonance generated by the solitonic matter that drives the Wess-Zumino term that in the presence of $K^\star$ acts like a magnetic field.
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arxiv:hep-ph/0502049
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In the first part of the talk, I discussed results on the determination of the ratios of the light quark masses from large N_c chiral perturbation theory, to be described elsewhere. The following notes contain material from the second part of the talk, which concerns the implications of large N_c for resonance dominance estimates of the low energy coupling constants in chiral perturbation theory.
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arxiv:hep-ph/0502065
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If physics at the Planck scale requires new conceptions of space-time, then generic renormalizable field theories predict observable violations of Lorentz invariance in the low energy sector. The little recognized ``Lorentz Fine Tuning Problem'' comes from logarithmic loop corrections which are not suppressed to the enormous extent commonly assumed. Fine-tuning of parameters at the Planck scale is one possible but unpalatable solution. Here we show that violation of Lorentz invariance is highly suppressed in a supersymmetric theory, the Wess-Zumino model. We conjecture that supersymmetry may be further motivated by yet another fine tuning problem of ordinary quantum field theories.
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arxiv:hep-ph/0502106
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In this note we calculate the form of electroweak corrections in deconstructed Higgsless models for the case of a fermion whose weak properties arise from two adjacent SU(2) groups on the deconstructed lattice. We show that, as recently proposed in the continuum, it is possible for the value of the electroweak parameter alpha S to be small in such a model. In addition, by working in the deconstructed limit, we may directly evaluate the size of off-Z-pole electroweak corrections arising from the exchange of Kaluza-Klein modes; this has not been studied in the continuum. The size of these corrections is summarized by the electroweak parameter alpha delta. In one-site delocalized Higgsless models with small values of alpha S, we show that the amount of delocalization is bounded from above, and must be less than 25% at 95% CL. We discuss the relation of these calculations to our previous calculations in deconstructed Higgsless models, and to models of extended technicolor. We present numerical results for a four-site model, illustrating our analytic calculations.
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arxiv:hep-ph/0502162
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We present a determination of the QCD parameter Lambda in the quenched approximation (n_f=0) and for two flavours (n_f=2) of light dynamical quarks. The calculations are performed on the lattice using O(a) improved Wilson fermions and include taking the continuum limit. We find Lambda_{n_f=0} = 259(1)(20) MeV and Lambda_{n_f=2} = 261(17)(26) MeV}, using r_0 = 0.467 fm to set the scale. Extrapolating our results to five flavours, we obtain for the running coupling constant at the mass of the Z boson alpha_s(m_Z) = 0.112(1)(2). All numbers refer to the MSbar scheme.
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arxiv:hep-ph/0502212
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We explore the effects of breaking and restoration of chiral and axial symmetries using an extended three-flavor Nambu-Jona-Lasinio model that incorporates explicitly the axial anomaly through the 't Hooft interaction. We implement a temperature (density) dependence of the anomaly coefficient motivated by lattice results for the topological susceptibility. The spectrum of scalar and pseudoscalar mesons is analyzed bearing in mind the identification of chiral partners and the study of its convergence. We also concentrate on the behavior of the mixing angles that give us relevant information on the issue under discussion. The results suggest that the axial part of the symmetry is restored before the possible restoration of the full U(3)$\otimes$U(3) chiral symmetry might occur.
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arxiv:hep-ph/0502217
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Two- and three-particle distribution amplitudes of heavy pseudoscalar mesons of well-defined geometric twist are introduced. They are obtained from appropriately parametrized vacuum-to-meson matrix elements by applying those twist projectors which determine the enclosed light-cone operators of definite geometric twist and, in addition, observing the heavy quark constraint. Comparing these distribution amplitudes with the conventional ones of dynamical twist we derive relations between them, partially being of Wandzura-Wilczek type; also sum rules of Burkhardt-Cottingham type are derived.The derivation is performed for the (double) Mellin moments and then re-summed to the non-local distribution amplitudes. Furthermore, a parametrization of vacuum-to-meson matrix elements for non-local operators off the light-cone in terms of distribution amplitudes accompanying independent kinematical structures is derived.
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arxiv:hep-ph/0502239
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We study the decays of $B\to K^{(*)} \ell^{+} \ell^{-}$ in split supersymmetry with R-parity violation. We find that the decay branching ratio of $B\to K\tau^+\tau^-$ in the new physics model due to the scalar interactions can be $1.8\times 10^{-6}$ which is about one order of magnitude larger that in the standard model, whereas those of $B\to K\ell^+\ell^-$ ($\ell=e$ and $\mu$) and the $K^*$ modes are insensitive to the new physics. On the other hand, the forward-backward asymmetries of $B\to K \tau^{+} \tau^{-}$ and $K\mu^{+}\mu^{-}$, vanishing in the standard model, can be over 10 and 1%, respectively. In addition, we show that the new interactions will significantly change the forward-backward asymmetry in $B\to K^* \tau^{+} \tau^{-}$.
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arxiv:hep-ph/0502246
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We discuss the AGK rules for the exchange of an arbitrary number of reggeized gluons in perturbative QCD in the high energy limit. Results include the cancellation of corrections to single jet and double jet inclusive cross sections, both for hard and soft rescattering contributions.
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arxiv:hep-ph/0503049
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The generation of a kination-dominated phase by a quintessential exponential model is investigated and the parameters of the model are restricted so that a number of observational constraints (originating from nucleosynthesis, the present acceleration of the universe and the dark-energy-density parameter) are satisfied. The decoupling of a thermal cold dark matter particle during the period of kination is analyzed, the relic density is calculated both numerically and semi-analytically and the results are compared with each other. It is argued that the enhancement, with respect to the standard paradigm, of the cold dark matter abundance can be expressed as a function of the quintessential density parameter at the onset of nucleosynthesis. We find that values of the latter quantity close to its upper bound require the thermal-averaged cross section times the velocity of the cold relic to be almost three orders of magnitude larger than this needed in the standard scenario so as compatibility with the cold dark matter constraint is achieved.
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arxiv:hep-ph/0503080
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We study the Lambda_QCD/M_B corrections from subleading shape functions in inclusive B-meson decays. We propose a natural and smooth interpolation from the endpoint region to the full phase space, and derive expressions for the triple differential decay rate in B -> X_u l nu and the photon energy spectrum in B -> X_s gamma. Our results are valid to order Lambda_QCD/M_B for hadronic invariant masses of order Lambda_QCD M_B and to order Lambda_QCD^2/M_B^2 for larger hadronic masses. They allow a systematic investigation of the transition between the separate regimes of the local and nonlocal expansions, and can be used to study decay distributions in any kinematic variables. We consider several examples of interest and point out that a combined measurement of hadronic energy and invariant mass provides an alternative to the extraction of |V_ub| which is largely independent of shape function effects and in principle allows a higher accuracy than the combined measurement of leptonic and hadronic invariant masses. We perform the expansion directly in QCD light-cone operators, and give a discussion of the general basis of light-cone operators. Reparametrization invariance under the change of the light-cone direction reduces the number of independent shape functions. We show that differing previous results for the lepton energy spectrum obtained from different choices of light-cone coordinates are in agreement.
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arxiv:hep-ph/0503095
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Electroweak production of single top quarks is an as-yet-unverified prediction of the Standard model, potentially sensitive to new physics. Two of the single top quark productions channels have significant charge asymmetries at the LHC, while the much larger background from $t\bar{t}$ is nearly charge-symmetric. This can be used to reduce systematic uncertainties and make precision measurements of single top quark production.
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arxiv:hep-ph/0503110
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Transverse single-spin asymmetries (SSA) in inclusive reactions are now considered to be directly related to the transverse momentum ${\bf k}_{T}$ of the fundamental partons involved in the process. We find that the ideal probe to extract information on the gluon Sivers function is the transverse SSA of prompt photon production $p p^{\uparrow} \to \gamma X$, at large $p_T$. The following related processes, $p p^{\uparrow} \to \gamma + jet + X$, $p p^{\uparrow} \to \gamma^* + X \to \mu^+ \mu^- + X$ and $\bar{p} p^{\uparrow} \to \gamma + X$ are also briefly discussed.
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arxiv:hep-ph/0503127
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In a model with Lorentz invariance violation implemented through modified dispersion relations, we estimate the rate for the decay process gamma -> 3 gamma and find that it provides a relevant bound on Lorentz invariance violation.
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arxiv:hep-ph/0503130
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We investigate split supersymmetry (SUSY) within a supergravity framework, where local SUSY is broken by the F-term of a hidden sector chiral superfield X. With reasonably general assumptions, we show that the fermionic component of X will always have mass within a Tev. Though its coupling to the observable sector superfields is highly suppressed in Tev scale SUSY, we show that it can be enhanced by many orders in split SUSY, leading to its likely participation in accelerator phenomenology.We conclude with a specific example of such a scenario in a string based supergravity model.
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arxiv:hep-ph/0503167
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We have calculated the full one-loop electroweak (EW) and QCD corrections to the third generation scalar-fermion pair production processes $e^+e^- \to \gamma \gamma \to \tilde{f_i}\bar{\tilde{f_i}} (f=t,b,\tau)$ at an electron-positron linear collider(LC) in the minimal supersymmetric standard model (MSSM). We analyze the dependence of the radiative corrections on the parameters such as the colliding energy $\sqrt{\hat s}$ and the SUSY fundamental parameters $A_f$, $\tan \beta$, $\mu$, $M_{SUSY}$ and so forth. The numerical results show that the EW corrections to the squark-, stau-pair production processes and QCD corrections to the squark-pair production processes give substantial contributions in some parameter space. The EW relative corrections to squark-pair production processes can be comparable with QCD corrections at high energies. Therefore, these EW and QCD corrections cannot be neglected in precise measurement of sfermion pair productions via $\gamma\gamma$ collision at future linear colliders.
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arxiv:hep-ph/0503171
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We study three-body charmless baryonic B decays of $B \to \Lambda\bar\Lambda P$ with $P=\pi$ and $K$ in the standard model. We find that the branching ratios of the $K$ modes are about one order of magnitude larger than those of the corresponding $\pi$ modes unlike the cases of $B\to p\bar p P$. Explicitly, we obtain that $Br(B^-\to \Lambda\bar \Lambda K^-)=(2.8\pm 0.2)\times 10^{-6}$ and $Br(\bar B^0 \to\Lambda\bar \Lambda \bar K^0)=(2.5\pm 0.3)\times 10^{-6}$. The former agrees well with the BELLE experimental measurement of $(2.91^{+0.90}_{-0.70}\pm 0.38)\times 10^{-6}$, while the latter should be seen at the ongoing B factories soon.
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arxiv:hep-ph/0503264
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Motivated by the apparent need for extending the MSSM and perhaps mitigating naturalness problems associated with the $\mu$ parameter and fine-tuning of the soft masses, we augment the MSSM spectrum by a SM gauge singlet chiral superfield, and enlarge the gauge structure by an additional U(1)' invariance, so that the gauge and Higgs sectors are relatively secluded. One crucial aspect of U(1)' models is the existence of anomalies, cancellation of which may require the inclusion of exotic matter which in turn disrupts the unification of the gauge couplings. In this work we pursue the question of canceling the anomalies with a minimal matter spectrum and no exotics. This can indeed be realized provided that U(1)' charges are family-dependent and the soft-breaking sector includes non-holomorphic operators for generating the fermion masses. We provide the most general solutions for U(1)' charges by taking into account all constraints from gauge invariance and anomaly cancellation. We analyze various laboratory and astrophysical bounds ranging from fermion masses to relic density, for an illustrative set of parameters. The U(1)' charges admit patterns of values for which family nonuniversality resides solely in the lepton sector, though this does not generate leptonic FCNCs due to the U(1)' gauge invariance.
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arxiv:hep-ph/0503290
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In supersymmetric models with gravity-mediated SUSY breaking, universality of soft SUSY breaking sfermion masses m_0 is motivated by the need to suppress unwanted flavor changing processes. The same motivation, however, does not apply to soft breaking Higgs masses, which may in general have independent masses from matter scalars at the GUT scale. We explore phenomenological implications of both the one-parameter and two-parameter non-universal Higgs mass models (NUHM1 and NUHM2), and examine the parameter ranges compatible with Omega_CDM h^2, BF(b --> s,gamma) and (g-2)_mu constraints. In contrast to the mSUGRA model, in both NUHM1 and NUHM2 models, the dark matter A-annihilation funnel can be reached at low values of tan(beta), while the higgsino dark matter annihilation regions can be reached for low values of m_0. We show that there may be observable rates for indirect and direct detection of neutralino cold dark matter in phenomenologically aceptable ranges of parameter space. We also examine implications of the NUHM models for the Fermilab Tevatron, the CERN LHC and a Sqrt(s)=0.5-1 TeV e+e- linear collider. Novel possibilities include: very light s-top_R, s-charm_R squark and slepton_L masses as well as light charginos and neutralinos and H, A and H^+/- Higgs bosons.
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arxiv:hep-ph/0504001
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We study O(alpha^2 beta_0) perturbative corrections to matrix elements entering two-body exclusive decays of the form B -> pi pi, pi K in the QCD factorization formalism, including chirally enhanced power corrections, and discuss the effect of these corrections on direct CP asymmetries, which receive their first contribution at O(alpha). We find that the O(alpha^2 beta_0) corrections are often as large as the O(alpha) corrections. We find large uncertainties due to renormalization scale dependence as well as poor knowledge of the non-perturbative parameters. We assess the effect of the perturbative corrections on the direct CP violation parameters of B -> pi^+ pi^-.
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arxiv:hep-ph/0504024
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We explore the possibility of simultaneous determination of neutrino mass hierarchy and the CP violating phase by using two identical detectors placed at different baseline distances. We focus on a possible experimental setup using neutrino beam from J-PARC facility in Japan with beam power of 4MW and megaton (Mton)-class water Cherenkov detectors, one placed in Kamioka and the other at somewhere in Korea. We demonstrate, under reasonable assumptions of systematic uncertainties, that the two-detector complex with each fiducial volume of 0.27 Mton has potential of resolving neutrino mass hierarchy up to sin^2 2theta_{13} > 0.03 (0.055) at 2\sigma (3\sigma) CL for any values of delta and at the same time has the sensitivity to CP violation by 4 + 4 years running of nu_e and nu_e-bar appearance measurement. The significantly enhanced sensitivity is due to clean detection of modulation of neutrino energy spectrum, which is enabled by cancellation of systematic uncertainties between two identical detectors which receive the neutrino beam with the same energy spectrum in the absence of oscillations.
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arxiv:hep-ph/0504026
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We analyse the Balitsky-Kovchegov (BK) saturation equation in momentum space and solve it numerically. We confirm that, in the limit where the transverse momentum of the incident particle k is much bigger than the momentum transfer q, the equation admits travelling-wave solutions. We extract the q dependence of the saturation scale Q_s(Y) and verify that Q_s(Y=cste) scales as max(q,Q_T), where Q_T is the scale caracterizing the target.
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arxiv:hep-ph/0504080
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We calculate the amplitudes of J^{PC}=3^{--} meson production in diffractive DIS within the k_t-factorization approach, with a particular attention paid to the rho_3(1690) meson. We find that at all Q^2 the rho_3(1690) production cross section is 2-5 times smaller than the rho(1700) production cross section, which is assumed to be a pure D-wave state. Studying sigma_L and sigma_T separately, we observe domination of rho_3 in sigma_L and domination of rho(1700) in sigma_T and offer an explanation of this behavior in simple terms. We also find very strong contributions -- sometimes even domination -- of the s-channel helicity violating amplitudes. The typical color dipole sizes probed in rho_3 production are shown to be larger than those in the ground state rho production, and the energy dependence of rho_3 cross section turns out to be much flatter than the rho production cross section. All the conclusions about the relative behavior of rho_3(1690) and rho(1700) mesons are numerically stable against variations of input parameters.
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arxiv:hep-ph/0504139
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We calculate the screening potential of a fast parton moving through a quark-gluon plasma in the framework of semi-classical transport theory. We found an anisotropic potential showing a minimum in the direction of the parton velocity. Possible consequences of this potential on binary states in a quark-gluon plasma are discussed.
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arxiv:hep-ph/0504174
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We have found in [1] new conditions for a total neutrino conversion in the case of neutrino oscillations taking place in a medium, consisting of n = 2 (or 3) alternating layers with constant densities $N_1$ and $N_2$. It is claimed in [4] that our results are particular case of enhancement of neutrino oscillations, which was suggested earlier by other authors and was widely discussed in the literature. We refute these claims, confirming the novelty of our results.
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arxiv:hep-ph/0504247
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It is investigated under which conditions an adiabatic adaption of the dynamic and spectral information of vector mesons to the changing medium in heavy ion collisions, as assumed in schematic model calculations and microscopic transport simulations, is a valid assumption. Therefore time dependent medium modifications of low mass vector mesons are studied within a non-equilibrium quantum field theoretical description. Timescales for the adaption of the spectral properties are given and non-equilibrium dilepton yields are calculated, leading to the result that memory effects are not negligible for most scenarios.
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arxiv:hep-ph/0504278
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A problem, whether a neutrino-antineutrino transition could be responsible for the muon neutrino deficit found in underground experiments (Super-Kamiokande, MACRO, Soudan 2) and in the accelerator long-baseline K2K experiment, is discussed in this paper. The intention of the work is not consideration of concrete models for muon neutrino-antineutrino transition but a desire to attract an attention to another possibility of understanding the nature of the measured muon neutrino deficit in neutrino experiments.
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arxiv:hep-ph/0504282
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Some recent developments in the study of light and heavy pentaquarks are reviewed, mainly within constituent quark models. Emphasis is made on results obtained in the flavor-spin model where a nearly ideal octet-antidecuplet mixing is obtained. The charmed antisextet is reviewed in the context of an SU(4) classification.
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arxiv:hep-ph/0504284
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In the light of new experimental results on B -> K pi decays, we critically study the decay processes B -> K pi in a phenomenological way. Using the quark diagram approach and the currently available data, we determine the allowed values of the relevant theoretical parameters, corresponding to the electroweak (EW) penguin, the color-suppressed tree contribution, etc. In order to find the most likely values of the parameters in a statistically reliable way, we use the chi^2 minimization technique. Our result shows that the current data for B to K pi decays strongly indicate (large) enhancements of both the EW penguin and the color-suppressed tree contributions. In particular, the color-suppressed tree effect needs to be enhanced by about an order of magnitude to fit the present data.
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arxiv:hep-ph/0505060
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The diquark condensate susceptibility in neutral color superconductor at moderate baryon density is calculated in the frame of two flavor Nambu-Jona-Lasinio model. When color chemical potential is introduced to keep charge neutrality, the diquark condensate susceptibility is negative in the directions without diquark condensate in color space, which may be regarded as a signal of the instability of the conventional ground state with only diquark condensate in the color 3 direction.
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arxiv:hep-ph/0505061
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We report OPE predictions for hadronic mass and q^2 moments in inclusive semileptonic B decays without charm, taking into account experimental cuts on the charged lepton energy and on the hadronic invariant mass, and address the related theoretical uncertainty.
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arxiv:hep-ph/0505091
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We use phenomenological nonlocal Lagrangians, which lead to non trivial forms for the quark propagator, to describe the pion. We define a procedure, based on the Dyson-Schwinger equations, for the calculation of the pion parton distributions at low Q^2. The obtained parton distributions fulfill all the wishful properties. Using a convolution approach we incorporate the composite character of the constituent quarks in the formalism. We evolve, using the Renormalization Group, the calculated parton distributions to the experimental scale and compare favorably with the data and draw conclusions.
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arxiv:hep-ph/0505102
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We present a code to compute the relic density of dark matter in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). Dominant corrections to the Higgs masses are calculated with NMHDECAY as well as theoretical and collider constraints. All neutralino annihilation and coannihilation processes are then computed with an extended version of micrOMEGAs, taking into acount higher order corrections to Higgs vertices. We explore the parameter space of the NMSSM and consider in particular the case of a bino LSP, of a mixed bino-higgsino LSP and of a singlino LSP. As compared to the MSSM, neutralino annihilation is often more efficient as it can take place via (additional) Higgs resonances as well as annihilation into light Higgs states. Models with a large singlino component can be compatible with WMAP constraints.
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arxiv:hep-ph/0505142
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Using an expanded form of Planck-Bohr's quantization method and phenomenological formulae,} {\small we deduce the rest masses and intrinsic quantum numbers (I, S, C, b and Q) of all kinds of the lowest energy quarks and baryons, from only one elementary quark family}$\epsilon $ {\small with S = C = b = 0. The deduced quantum numbers match those found in experiments. The deduced rest masses are consistent with experimental results. This paper predicts some quarks $\text{u}_{C}\text{(6073),}$}d$_{S}${\small (9613)} {\small $\text{and d}_{b}\text{(9333)}$and baryons $\Lambda_{c}^{+}$% (6696), $\Lambda_{b}$(9959)and $\Lambda $(10239).
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arxiv:hep-ph/0505184
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The importance and signatures of cosmic tau--(anti)neutrinos have been studied for upward-- and downward--going $\mu^-+\mu^+$ and hadronic shower event rates relevant for present and future underground water or ice detectors, utilizing the unique and reliable ultrasmall--$x$ predictions of the dynamical (radiative) parton model. The upward--going $\mu^- +\mu^+$ event rates calculated just from cosmic $\nu_{\mu}+\bar{\nu}_{\mu}$ fluxes are sizeably enhanced by taking into account cosmic $\nu_{\tau}+ \bar{\nu}_{\tau}$ fluxes and their associated $\tau^- +\tau^+$ fluxes as well. The coupled transport equations for the upward--going $\stackrel{(-)}{\nu}_{\tau}$ flux traversing the Earth imply an enhancement of the attenuated and regenerated $\stackrel{(-)}{\nu}_{\tau}$ flux typically around $10^4-10^5$ GeV with respect to the initial cosmic flux. This enhancement turns out to be smaller than obtained so far, in particular for flatter initial cosmic fluxes behaving like $E_{\nu}^{-1}$. Downward--going $\mu^- +\mu^+$ events and in particular the background--free and unique hadronic `double bang' and `lollipop' events allow to test downward--going cosmic $\nu_{\tau} +\bar{\nu}_{\tau}$ fluxes up to about $10^9$ GeV.
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arxiv:hep-ph/0505218
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We consider multi-parton collinear limits of QCD amplitudes at tree level. Using the MHV formalism we specify the underlying analytic structure of the resulting multi-collinear splitting functions. We derive general results for these splitting functions that are valid for specific numbers of negative helicity partons and an arbitrary number of positive helicity partons (or vice versa).
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arxiv:hep-ph/0505219
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Using the latest data pertaining to \bar u-\bar d asymmetry and the spin polarization functions, detailed implications of the possible values of the coupling strength of the singlet Goldstone boson \eta' have been investigated in the \chiCQM with configuration mixing. Using \Delta u, \Delta_3, \bar u-\bar d and \bar u/\bar d, the possible ranges of the coupling parameters a, \alpha^ 2, \beta^ 2 and \zeta^ 2, representing respectively the probabilities of fluctuations to pions, K, \eta and \eta^{'}, are shown to be 0.10 \lesssim a \lesssim 0.14, 0.2\lesssim \alpha \lesssim 0.5, 0.2\lesssim \beta \lesssim 0.7 and 0.10 lesssim |\zeta| \lesssim 0.70. To constrain the coupling strength of \eta', detailed fits have been obtained for spin polarization functions, quark distribution functions and baryon octet magnetic moments corresponding to the following sets of parameters: a=0.1, \alpha=0.4, \beta=0.7, |\zeta|=0.65 (Case I); a=0.1, \alpha=0.4, \beta=0.6, |\zeta|=0.70 (Case II); a=0.14, \alpha=0.4, \beta=0.2, \zeta=0 (Case III) and a=0.13, \alpha=\beta=0.45, |\zeta|=0.10 (Case IV). Case I represents the calculations where a is fixed to be 0.1, in accordance with earlier calculations, whereas other parameters are treated free and the Case IV represents our best fit. The fits clearly establish that a small non-zero value of the coupling of \eta' is preferred over the higher values of \eta' as well as when \zeta=0, the latter implying the absence of \eta' from the dynamics of \chiCQM. Our best fit achieves an overall excellent fit to the data, in particular the fit for \Delta u, \Delta d, \Delta_8 as well as the magnetic moments \mu_{n}, \mu_{\Sigma^-}, \mu_{\Sigma^+} and \mu_{\Xi^-} is almost perfect, the \mu_{\Xi^-} being a difficult case for most of the similar calculations.
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arxiv:hep-ph/0505224
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Assuming 3-$\nu$ mixing, massive Majorana neutrinos and neutrinoless double-beta (\betabeta-) decay generated only by the (V-A) charged current weak interaction via the exchange of the three Majorana neutrinos, we briefly review the predictions for the effective Majorana mass $\meff$ in \betabeta-decay and reanalyse the physics potential of future \betabeta-decay experiments to provide information on the type of neutrino mass spectrum, the absolute scale of neutrino masses, and Majorana CP-violation in the lepton sector. Using as input the most recent experimental results on neutrino oscillation parameters and the prospective precision that can be achieved in future measurements of the latter, we perform a statistical analysis of a \betabeta-decay half-life measurement taking into account experimental and theoretical errors, as well as the uncertainty implied by the imprecise knowledge of the corresponding nuclear matrix element (NME). We show, in particular, how the possibility to discriminate between the different types of neutrino mass spectra and the constraints on the absolute neutrino mass scale depend on the mean value and the experimental error of $\meff$ and on the NME uncertainty. The constraints on Majorana CP-violation phases in the neutrino mixing matrix, which can be obtained from a measurement of $\meff$ and additional data on the sum of neutrino masses, are also investigated in detail. We estimate the required experimental accuracies on both types of measurements, and the required precision in the NME permitting to address the issue of Majorana CP-violation in the lepton sector.
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arxiv:hep-ph/0505226
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The basis of renormalon calculus is briefly discussed. The method is applied to study QCD predictions for three sum rules of deep-inelastic scattering, namely for the Gross-Llewellyn Smith, Bjorken polarized and unpolarized sum rules. It is shown that the renormalon structures of theses sum rules are closely related. These properties are giving us the hint that theoretical expressions of these three sum rules are similar both in the and non-perturbative sectors. Some phenomenological consequances of the new relations are discussed.
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arxiv:hep-ph/0505230
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The Standard Model Extension (SME) provides the most general observer-independent field theoretical framework for investigations of Lorentz violation. The SME lagrangian by definition contains all Lorentz-violating interaction terms that can be written as observer scalars and that involve particle fields in the Standard Model and gravitational fields in a generalized theory of gravity. This includes all possible terms that could arise from a process of spontaneous Lorentz violation in the context of a more fundamental theory, as well as terms that explicitly break Lorentz symmetry. An overview of the SME is presented, including its motivations and construction. Some of the theoretical issues arising in the case of spontaneous Lorentz violation are discussed, including the question of what happens to the Nambu-Goldstone modes when Lorentz symmetry is spontaneously violated and whether a Higgs mechanism can occur. A minimal version of the SME in flat Minkowski spacetime that maintains gauge invariance and power-counting renormalizability is used to search for leading-order signals of Lorentz violation. Recent Lorentz tests in QED systems are examined, including experiments with photons, particle and atomic experiments, proposed experiments in space and experiments with a spin-polarized torsion pendulum.
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arxiv:hep-ph/0506054
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In theories with extra dimensions it is well known that the Lorentz invariance of the $D=4+n$-dimensional spacetime is lost due to the compactified nature of the $n$ dimensions leaving invariance only in 4d. In such theories other sources of Lorentz violation may exist associated with the physics that initiated the compactification process at high scales. Here we consider the possibility of capturing some of this physics by analyzing the higher dimensional analog of the model of Colladay and Kostelecky. In that scenario a complete set of Lorentz violating operators arising from spontaneous Lorentz violation, that are not obviously Planck-scale suppressed, are added to the Standard Model action. Here we consider the influence of the analogous set of operators which break Lorentz invariance in 5d within the Universal Extra Dimensions picture. We show that such operators can greatly alter the anticipated Kaluza-Klein(KK) spectra, induce electroweak symmetry breaking at a scale related to the inverse compactification radius, yield sources of parity violation in, e.g., 4d QED/QCD and result in significant violations of KK-parity conservation produced by fermion Yukawa couplings, thus destabilizing the lightest KK particle. LV in 6d is briefly discussed.
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arxiv:hep-ph/0506056
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The effects of loop contributions to the electroweak precision observables and m_h in the MSSM with non-minimal flavour violation (NMFV) are analyzed, including the mixing between third and second generation squarks. The mixing-induced shift in M_W can amount to 140 MeV and to 70x10^{-5} in sin^2 \theta_{eff} for extreme values of squarks mixing, allowing to set limits on the NMFV parameters. The corrections for m_h are usually small and can amount up to O(5 GeV) for large flavour violation.
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arxiv:hep-ph/0506104
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We show that for gaugino mediated supersymmetry breaking the gravitino mass is bounded from below. For a size of the compact dimensions of order the unification scale and a cutoff given by the higher-dimensional Planck mass, we find $m_{3/2} \gtrsim 10 GeV$. In a large domain of parameter space, the gravitino is the lightest superparticle with a scalar $\tilde\tau$-lepton as the next-to-lightest superparticle.
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arxiv:hep-ph/0506105
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Expected event rates for a number of dark matter nuclear targets were calculated in the effective low-energy minimal supersymmetric standard model, provided the lightest neutralino is the dark matter Weakly Interacting Massive Particle (WIMP). These calculations allow direct comparison of sensitivities of different dark matter detectors to intermediate mass WIMPs expected from the measurements of the DArk MAtter (DAMA) experiment.
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arxiv:hep-ph/0506195
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We consider gauge field theories in the presence of ensembles of vector backgrounds. While Lorentz invariance is explicitely broken in the presence of any single background, here, the Lorentz invariance of the theory is restored by averaging over a Lorentz invariant ensemble of backgrounds, i.e. a set of background vectors that is mapped onto itself under Lorentz transformations. This framewkork is used to study the effects of a non-trivial but Lorentz invariant vacuum structure or mass dimension two vector condensates by identifying the background with a shift of the gauge field. Up to now, the ensembles used in the literature comprise configurations corresponding to non-zero field tensors together with such with vanishing field strength. We find that even when constraining the ensembles to pure gauge configurations, the usual high-energy degrees of freedom are removed from the spectrum of asymptotic states in the presence of said backgrounds in euclidean and in Minkowski space. We establish this result not only for the propagators to all orders in the background and otherwise at tree level but for the full propagator.
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arxiv:hep-ph/0506210
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In charmless nonleptonic B decays to \pi\pi or \rho\rho, the "color allowed" and "color suppressed" tree amplitudes can be studied in a systematic expansion in \alphas(mb) and \Lambda/mb. At leading order in this expansion their relative strong phase vanishes. The implications of this prediction are obscured by penguin contributions. We propose to use this prediction to test the relative importance of the various penguin amplitudes using experimental data. The present B->\pi\pi data suggest that there are large corrections to the heavy quark limit, which can be due to power corrections to the tree amplitudes, large up-quark penguin amplitude, or enhanced weak annihilation. Because the penguin contributions are smaller, the heavy quark limit is more consistent with the B->\rho\rho data, and its implications may become important for the extraction of \alpha from this mode in the future.
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arxiv:hep-ph/0506228
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Why the charged lepton mass formula m_e +m_\mu +m_\tau = {2/3} (\sqrt{m_e}+\sqrt{m_\mu} +\sqrt{m_\tau})^2 is mysterious is reviewed, and guiding principles to solve the mystery are presented. According to the principles, an example of such a mass generation mechanism is proposed, where the origin of the mass spectrum is attributed not to the structure of the Yukawa coupling constants, but to a structure of vacuum expectation values of flavor-triplet scalars under Z_4 \times S_3 symmetries.
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arxiv:hep-ph/0506247
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In this paper, we review the production cross section for charged and neutral Higgs bosons pairs in $e^{+}e^{-}$ collisions beyond the tree level, in the framework of the Minimal Supersymmetric Standard Model (MSSM). A complete list of formulas for all electroweak contributions at the one loop level is given. A numerical code has been developed in order to compute them accurately and, in turn, to compare the MSSM Higgs bosons pair production cross sections at tree level and at the one loop level.
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arxiv:hep-ph/0506274
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New analysis of the heavy, neutral MSSM Higgs bosons H and A production at the Photon Collider is presented for M_A = 200, 250, 300 and 350 GeV in the parameter range corresponding to the so called "LHC wedge" and beyond. The expected precision of the cross section measurement for the process gamma+gamma->A,H->b+bbar and the "discovery reach" of the Photon Collider are compared for different MSSM scenarios. The analysis takes into account all relevant theoretical and experimental issues which could affect the measurement. For MSSM Higgs bosons A and H, for M_A = 200-350 GeV and tan(beta)=7, the statistical precision of the cross-section determination is estimated to be 8-34%, after one year of Photon Collider running, for four considered MSSM parameters sets. As heavy neutral Higgs bosons in this scenario may not be discovered at LHC or at the first stage of the e+e- collider, an opportunity of being a discovery machine is also studied for the Photon Collider.
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arxiv:hep-ph/0507006
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We present a first estimate of the cross-section for the exclusive process gamma^*_L (Q_1^2) gamma^*_L(Q_2^2) -> rho^0_L rho^0_L, which will be studied in the future high energy e^+ e^- linear collider. As a first step, we calculate the Born order approximation of the amplitude for longitudinally polarized virtual photons and mesons, in the kinematical region s >> -t, Q_1^2, Q_2^2. This process is completely calculable in the hard region Q_1^2, Q_2^2 >> Lambda^2_{QCD}. We perform most of the steps in an analytical way. The resulting cross-section turns out to be large enough for this process to be measurable with foreseen luminosity and energy, for Q_1^2 and Q_2^2 in the range of a few GeV^2.
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arxiv:hep-ph/0507038
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We study the electromagnetic on-shell form factor of quarks in massless perturbative QCD. We derive the complete pole part in dimensional regularization at three loops, and extend the resummation of the form factor to the next-to-next-to-leading contributions. These results are employed to evaluate the infrared finite absolute ratio of the time-like and space-like form factors up to the fourth order in the strong coupling constant. Besides for the pole structure of higher-loop QCD amplitudes, our new contributions to the form factor are also relevant for the high-energy limit of massive gauge theories like QED. The highest-transcendentality component of our results confirms a result recently obtained in N=4 Super-Yang-Mills theory.
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arxiv:hep-ph/0507039
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In the context of pure QED, we obtain analytic expressions for the contributions to the Bhabha scattering differential cross section at order alpha^4 which originate from the interference of two-loop photonic vertices with tree-level diagrams and from the interference of one-loop photonic diagrams amongst themselves. The ultraviolet renormalization is carried out. The IR-divergent soft-photon emission corrections are evaluated and added to the virtual cross section. The cross section obtained in this manner is valid for on-shell electrons and positrons of finite mass, and for arbitrary values of the center of mass energy and momentum transfer. We provide the expansion of our results in powers of the electron mass, and we compare them with the corresponding expansion of the complete order alpha^4 photonic cross section, recently obtained in hep-ph/0501120. As a by-product, we obtain the contribution to the Bhabha scattering differential cross section of the interference of the two-loop photonic boxes with the tree-level diagrams, up to terms suppressed by positive powers of the electron mass. We evaluate numerically the various contributions to the cross section, paying particular attention to the comparison between exact and expanded results.
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arxiv:hep-ph/0507047
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With a view to exploring a new kind of phase transition in the process of hadronization of quark-gluon plasma (QGP) we investigate the occurrence of pentaquark baryons and tetraquark mesons in the system. For this purpose, the frame work of an analoguous Saha's ionization formula for the colored ions in the system is used. The study of color-ionic-fraction (CIF) of multiply (color) ionized to unionized quark clusters (termed as "quarkons") as a function of temperature is carried out. It is pointed out that not only the temperature of the fire-ball in the relativistic heavy ion collisions evolves with respect to space and time but also the CIF associated with a particular stage of ionization. Further, for the case of single color-ionization a correspondence of the present results with those available for the bubble nucleation mechanism in QGP is demonstrated.
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arxiv:hep-ph/0507054
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I review recent progress in perturbative QCD on two fronts: extending next-to-next-to-leading order QCD corrections to a broader range of collider processes, and applying twistor-space methods (and related spinoffs) to computations of multi-parton scattering amplitudes.
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arxiv:hep-ph/0507064
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An NLO photon parton parametrization is presented based on the existing $F_2^\gamma$ measurements from $e^+e^-$ data and the low-$x$ proton structure function from $ep$ interactions. Also included in the extraction of the NLO parton distribution functions are the dijets data coming from $\gamma p \to j_1 + j_2 +X$. The new parametrization is compared to other available NLO parametrizations.
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arxiv:hep-ph/0507091
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We present the Mathematica package HypExp which allows to expand hypergeometric functions $_JF_{J-1}$ around integer parameters to arbitrary order. At this, we apply two methods, the first one being based on an integral representation, the second one on the nested sums approach. The expansion works for both symbolic argument $z$ and unit argument. We also implemented new classes of integrals that appear in the first method and that are, in part, yet unknown to Mathematica.
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arxiv:hep-ph/0507094
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We consider the collider phenomenology of split-supersymmetry models. Despite the challenging nature of the signals in these models the long-lived gluino can be discovered with masses above 2 TeV at the LHC. At a future linear collider we will be able to observe the renormalization group effects from split supersymmetry on the chargino/neutralino mixing parameters, using measurements of the neutralino and chargino masses and cross sections. This indirect determination of chargino/neutralino anomalous Yukawa couplings is an important check for supersymmetric models in general.
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arxiv:hep-ph/0507137
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Current neutrino oscillation data from solar, atmospheric, and reactor experiments are consistent with the neutrino mixing matrix elements taking values sin^2\theta_{12} = 1/3, sin^2\theta_{23} = 1/2, and sin^2\theta_{13}=0. We present a class of renormalizable gauge models which realize such a geometric mixing pattern naturally. These models, which are based on the non--Abelian discrete symmetry A_4, place significant restrictions on the neutrino mass spectrum, which we analyze. It is shown that baryogenesis via leptogenesis occurs quite naturally, with a single phase (determined from neutrino oscillation data) appearing in leptonic asymmetry and in neutrinoless double beta decay. Such predicted correlations would provide further tests of this class of models.
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arxiv:hep-ph/0507217
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The measurements of kinematical endpoints, in cascade decays of supersymmetric particles, in principle allow for a determination of the masses of the unstable particles. However, in this procedure ambiguities often arise. We here illustrate how such ambiguities arise. They can be resolved by a precise determination of the LSP mass, provided by the Linear Collider.
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arxiv:hep-ph/0507232
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We review QCD based descriptions of diffractive deep inelastic scattering emphasising the role of models with parton saturation. These models provide natural explanation of such experimentally observed facts as the constant ratio of the diffractive and total cross sections as a function of the Bjorken variable, and Regge factorization of diffractive parton distributions. The Ingelman-Schlein model and the soft color interaction model are also presented.
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arxiv:hep-ph/0507251
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The Skyrme-Faddeev-Niemi (SFN) model which is an O(3) $\sigma$ model in three dimensional space upto fourth-order in the first derivative is regarded as a low-energy effective theory of SU(2) Yang-Mills theory. One can show from the Wilsonian renormalization group argument that the effective action of Yang-Mills theory recovers the SFN in the infrared region. However, the thoery contains an additional fourth-order term which destabilizes the soliton solution. In this paper, we derive the second derivative term perturbatively and show that the SFN model with the second derivative term possesses soliton solutions.
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arxiv:hep-ph/0507258
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In this paper we construct analytically a LOFF color superconducting state that is both color and charge neutral using the weak coupling approximation. We demonstrate that this state is free from chromomagnetic instabilities. Its relevance to the realistic quark matter at moderately high baryon density is discussed.
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arxiv:hep-ph/0507306
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Using a three step quantization and phenomenological formulae, we can deduce the rest masses and intrinsic quantum numbers (I, S, C, B and Q) of quarks from only one unflavored elementary quark family $\epsilon$ with S = C = B = 0 in the vacuum. Then using sum laws, we can deduce the rest masses and intrinsic quantum numbers of baryons and meson from the deduced quarks. The deduced quantum numbers match experimental results exactly. The deduced rest masses are consistent with experimental results. This paper predicts some new quarks [d_{s}(773), d_{s}(1933), u_{c}(6073), d_{b}(9333)], baryons [$\Lambda_{c}$(6699), $\Lambda_{b}$(9959)] and mesons [D(6231), B(9502)]. PACS: 12.60.-i; 12.39.-x; 14.65.-q; 14.20.-c Key word: beyond the standard model
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arxiv:hep-ph/0507308
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In this paper, we study the chiral symmetry restoration in the hadronic spectrum in the framework of generalised Nambu-Jona-Lasinio quark models with instantaneous confining quark kernels. We investigate a heavy-light quarkonium and derive its bound-state equation in the form of a Schroedingerlike equation and, after the exact inverse Foldy-Wouthuysen transformation, in the form of a Diraclike quation. We discuss the Lorentz nature of confinement for such a system and demonstrate explicitly the effective chiral symmetry restoration for highly excited states in the mesonic spectrum. We give an estimate for the scale of this restoration.
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arxiv:hep-ph/0507330
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The beams of Linear Collider after main collision can be utilized to build neutrino factory with exceptional parameters. We also discuss briefly possible applications of some elements of proposed scheme for standard fixed target experiments, new experiments with \nu_\mu N interactions and in material sciences.
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arxiv:hep-ph/0507335
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A sum rule relation is proposed for direct CP asymmetries in $B\to K\pi$ decays. Leading terms are identical in the isospin symmetry limit, while subleading terms are equal in the flavor SU(3) and heavy quark limits. The sum rule predicts $A_{\rm CP}(B^0\to K^0\pi^0)=-0.17 \pm 0.06$ using current asymmetry measurements for the other three $B\to K\pi$ decays. A violation of the sum rule would be evidence for New Physics in $b\to s\bar qq$ transitions.
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arxiv:hep-ph/0508047
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We construct a top-mode standard model where the third generation fermions and the SU(2)_L \times U(1)_Y gauge bosons are put on a 6-dimensional brane(5-brane) with the extra dimensions compactified on the TeV scale(R_5^{-1}=R_6^{-1} \equiv R^{-1}= 1-10 TeV), while only the gluons live in a compactified 8-dimensional bulk(R_7^{-1}=R_8^{-1} \equiv \Lambda \gg R^{-1}).On the 5-brane, Kaluza-Klein (KK) modes of the bulk gluons give rise to induced four-fermion interactions which, combined with the gauge interactions, are shown to be strong enough to trigger the top quark condensate, based on the dynamics of 6-dimensional gauged Nambu-Jona-Lasinio (NJL) model. Moreover, we can use a freedom of the brane positions to tune the four-fermion coupling close to the critical line of 6-dimensional gauged NJL model, so that the gap equation can ensure the top condensate on the weak scale while keeping other fermions massless. There actually exists a scale (``tMAC scale''), \Lambda_{\rm tM} = (7.8-11.0) R^{-1}, where the running gauge couplings combined with the induced four-fermion interactions trigger only the top condensate while no bottom and tau condensates. Furthermore, presence of such explicit four-fermion interactions enables us to formulate straightforwardly the compositeness conditions at \Lambda=\Lambda_{\rm tM}, which, through the renormalization-group analysis, yields a prediction of masses of the top quark and the Higgs boson, m_t = 177 - 187 GeV and m_H = 183 - 207 GeV.
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arxiv:hep-ph/0508065
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We study the leptonic CP violation by employing the complete set of dimension-six pure leptonic effective operators. Connection among the observable at different energy scales can be made by the running of the renormalization group equations. Explicitly, we study the charged lepton electric dipole moment, muon Michel decay, and the triple spin-momentum correlations at the Linear Collider. We found the electron electric dipole moment, which starts at 2-loop level, severely constrains the possibilities to detect the CP violating signatures in muon decay and at the linear colliders.
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arxiv:hep-ph/0508076
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Motivated by the recent experimental data, we have revisited the $B\to \pi K,\pi \pi$ decays in the framework of QCD factorization, with inclusion of the important strong penguin corrections of order $\alpha_s^2$ induced by $b\to D g^\ast g^\ast$ ($D=d$ or $s$ and $g^\ast$ denotes an off-shell gluon) transitions. We find that these higher order strong penguin contributions can provide $\sim 30%$ enhancement to the penguin-dominated $B\to \pi K$ decay rates, and such an enhancement can improve the consistency between the theoretical predictions and the experimental data significantly, while for the tree-dominated $B\to \pi\pi$ decays, these higher order contributions play only a minor role. When these strong penguin contributions are summed, only a small strong phase remains and the direct CP asymmetries get small corrections. We also find patterns of the ratios between the CP-averaged branching fractions remain nearly unaffected even after including these higher order corrections and the $\pi K$ puzzle still persists. Our results may indicate that to resolve the puzzle one would have to resort to new physics contributions in the electroweak penguin sector as found by Buras {\it et al}.
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arxiv:hep-ph/0508079
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We consider the gauge-boson sector of a locally SU(2) x U(1) invariant effective Lagrangian with ten dimension-six operators added to the Lagrangian of the Standard Model. These operators induce anomalous three- and four-gauge-boson couplings and an anomalous gamma gamma H coupling. In the framework of this effective Lagrangian we calculate the helicity amplitudes and differential and total cross sections for the process gamma gamma --> WW at a photon collider. We give relations between different parts of the amplitudes that show which linear combinations of anomalous couplings are measurable in this reaction. The transformation properties of the differential cross section under CP are discussed. We find that three linear combinations of CP conserving and of CP violating couplings can be measured independently of the photon polarisation in gamma gamma --> WW.
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arxiv:hep-ph/0508132
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The dominant electroweak two-loop corrections to the precision observables M_W and s_w^eff are calculated in the MSSM. They are obtained by evaluating the two-loop Yukawa contributions of O(alpha_t^2), O(alpha_t alpha_b), O(alpha_b^2) to the quantity Delta rho. The result, involving the contributions from Standard Model fermions, sfermions, Higgs bosons and higgsinos, is derived in the gauge-less limit for arbitrary values of the lightest CP-even Higgs boson mass. A thorough discussion of the parameter relations enforced by supersymmetry is given, and two different renormalization schemes are applied. Compared to the previously known result for the quark-loop contribution we find a shift of up to +8 MeV in M_W and -4 * 10^-5 in s_w^eff. Detailed numerical estimates of the remaining uncertainties of M_W and s_w^eff from unknown higher-order contributions are obtained for different values of the supersymmetric mass scale.
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arxiv:hep-ph/0508139
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The possibility is considered that the verdict of the ongoing MiniBooNE neutrino experiment will favor neither of the contesting sides, stating in fact that the LSND effect with the original oscillation amplitude is not confirmed, but a new LSND effect with a considerably smaller amplitude is found (or, at least, strongly suggested). Then, in the framework of neutrino oscillations, the presence in Nature of hypothetical light sterile neutrinos (mixing with three active neutrinos with a weak strength) will be unambiguously suggested by post-MiniBooNE neutrino data (unless the credible CPT invariance is seriously violated). In the new situation, the 3+1 neutrino models may work all right. The same is true also for simple 3+2 neutrino models. For illustration of this potential developement, the simplest 3+2 model is briefly discussed.
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arxiv:hep-ph/0508145
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In the context of the supersymmetrized seesaw mechanism embedded in the Minimal Supersymmetric Standard Model (MSSM), complex neutrino Yukawa couplings can induce Electric Dipole Moments (EDMs) for the charged leptons, providing an additional route to seesaw parameters. However, the complex neutrino Yukawa matrix is not the only possible source of CP violation. Even in the framework of Constrained MSSM (CMSSM), there are additional sources, usually attributed to the phases of the trilinear soft supersymmetry breaking couplings and the mu-term, which contribute not only to the electron EDM but also to the EDMs of neutron and heavy nuclei. In this work, by combining bounds on various EDMs, we analyze how the sources of CP violation can be discriminated by the present and planned EDM experiments.
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arxiv:hep-ph/0508236
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A model is presented based on a dipole picture with a hard and a soft pomeron. It is assumed that large dipoles couple to the soft pomeron and small dipoels couple to the hard pomeron. Most of the parameters of the model are predetermined from proton-proton scattering and the only free parameter is the radius Rc, defining the transition from small to large dipoles. This is fixed by the proton structure function. The model then successfully predicts the proton charm and longitudinal structure functions, J/psi photoproduction, the DVCS cross section, the total gamma-p and gamma-gamma cross sections and the photon structure function.
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arxiv:hep-ph/0508261
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Recent analysis of the cosmic ray data together with earlier experimental measurements at ISR and SPS provides us a sound footing to discuss the behavior of total cross section at asymptotic energies. We will study the growth of total cross section at high energies in the light of various theoretical approaches with special reference to measurements at RHIC and LHC.
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arxiv:hep-ph/0508282
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We consider the parity doublet structure observed in high hadronic excitations within the instanton model for the QCD vacuum. In the conventional approach this doubling phenomenon is treated as a manifestation of the partial restoration of chiral or $U(1)_A$ symmetry. We demonstrate that the suppression of direct instanton contribution to the masses of excited hadrons leads to the partial $U(1)_A$ symmetry restoration in hadron spectrum. The origin of X(1835) resonance observed by BES Collaboration is studied upon the doublet structure. We argue also how X(1835) be interpreted as the lowest pseudoscalar glueball state, and derive its coupling constant to proton. It turns out that this coupling is large and negative. Demonstrated is how this large coupling affects the gluonic contribution to the proton spin.
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arxiv:hep-ph/0508288
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Bose-Einstein condensation (BEC) of composite diquarks in quark matter (the color superconductor phase) is discussed using the quasi-chemical equilibrium theory at a relatively low density region near the deconfinement phase transition, where dynamical quark-pair fluctuations are assumed to be described as bosonic degrees of freedom (diquarks). A general formulation is given for the diquark formation and particle-antiparticle pair-creation processes in the relativistic flamework, and some interesting properties are shown, which are characteristic for the relativistic many-body system. Behaviors of transition temperature and phase diagram of the quark-diquark matter are generally presented in model parameter space, and their asymptotic behaviors are also discussed. As an application to the color superconductivity, the transition temperatures and the quark and diquark density profiles are calculated in case with constituent/current quarks, where the diquark is in bound/resonant state. We obtained $T_C \sim 60-80$ MeV for constituent quarks and $T_C \sim 130$ MeV for current quarks at a moderate density ($\rho_b \sim 3 \rho_0$). The method is also developed to include interdiquark interactions into the quasi-chemical equilibrium theory within a mean-field approximation, and it is found that a possible repulsive diquark-diquark interaction lowers the transition temperature by nearly 50%.
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arxiv:hep-ph/0509029
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We resum to next-to-leading order the distribution in the ratio of the invariant hadron mass mX to the total hadron energy EX and the distribution in mX in the semileptonic decays B -> Xu l nu. By expanding our formulas, we obtain the coefficients of all the infrared logarithms at O(alphaS^2) and of the leading ones at O(alphaS^3). We explicitly show that the relation between these semileptonic spectra and the photon spectrum in the radiative decay B -> Xs gamma is not a purely short-distance one. There are long-distance effects in the semileptonic spectra which are not completely factorized by the structure function as measured in the radiative decay and have to be modelled in some way.
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arxiv:hep-ph/0509095
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We discuss the selection of fermion representations in technicolor models with a view toward minimizing technicolor contributions to the precision electroweak $S$ parameter. We present and analyze models that involve one technifermion SU(2)$_L$ doublet with standard-model singlet technifermion sectors that lead to walking behavior, which further reduces $S$. We also consider models that have technifermions in higher-dimensional representations and study embeddings in extended technicolor theories.
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arxiv:hep-ph/0509109
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We demonstrate the stability under subsequent-to-leading logarithm corrections of the quartic scalar-field coupling constant $\lambda$ and the running Higgs boson mass obtained from the (initially massless) effective potential for radiatively broken electroweak symmetry in the single-Higgs-Doublet Standard Model. Such subsequent-to-leading logarithm contributions are systematically extracted from the renormalization group equation considered beyond one-loop order. We show $\lambda$ to be the dominant coupling constant of the effective potential for the radiatively broken case of electroweak symmetry. We demonstrate the stability of $\lambda$ and the running Higgs boson mass through five orders of successively subleading logarithmic corrections to the scalar-field-theory projection of the effective potential for which all coupling constants except the dominant coupling constant $\lambda$ are disregarded. We present a full next-to-leading logarithm potential in the three dominant Standard Model coupling constants ($t$-quark-Yukawa, $\alpha_s$, and $\lambda$) from these coupling constants' contribution to two loop $\beta$- and $\gamma$-functions. Finally, we demonstrate the manifest order-by-order stability of the physical Higgs boson mass in the 220-231 GeV range. In particular, we obtain a 231 GeV physical Higgs boson mass inclusive of the $t$-quark-Yukawa and $\alpha_s$ coupling constants to next-to-leading logarithm order, and inclusive of the smaller $SU(2)\times U(1)$ gauge coupling constants to leading logarithm order.
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arxiv:hep-ph/0509122
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Using the QCD sum rule approach we investigate the possible four-quark structure of the recently observed charmed scalar mesons $D_0^{0}(2308)$ (BELLE) and $D_0^{0,+}(2405)$ (FOCUS) and also of the very narrow $D_{sJ}^{+}(2317)$, firstly observed by BABAR. We use diquak-antidiquark currents and work to the order of $m_s$ in full QCD, without relying on $1/m_c$ expansion. Our results indicate that a four-quark structure is acceptable for the resonances observed by BELLE and BABAR: $D_0^{0}(2308)$ and $D_{sJ}^{+}(2317)$ respectively, but not for the resonances observed by FOCUS: $D_0^{0,+}(2405)$.
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arxiv:hep-ph/0509131
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A future large-volume liquid scintillator detector would provide a high-statistics measurement of terrestrial antineutrinos originating from $\beta$-decays of the uranium and thorium chains. In addition, the forward displacement of the neutron in the detection reaction $\bar\nu_e+p\to n+e^+$ provides directional information. We investigate the requirements on such detectors to distinguish between certain geophysical models on the basis of the angular dependence of the geoneutrino flux. Our analysis is based on a Monte-Carlo simulation with different levels of light yield, considering both unloaded and gadolinium-loaded scintillators. We find that a 50 kt detector such as the proposed LENA (Low Energy Neutrino Astronomy) will detect deviations from isotropy of the geoneutrino flux significantly. However, with an unloaded scintillator the time needed for a useful discrimination between different geophysical models is too large if one uses the directional information alone. A Gd-loaded scintillator improves the situation considerably, although a 50 kt detector would still need several decades to distinguish between a geophysical reference model and one with a large neutrino source in the Earth's core. However, a high-statistics measurement of the total geoneutrino flux and its spectrum still provides an extremely useful glance at the Earth's interior.
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arxiv:hep-ph/0509136
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The long-sought "magnetic monopole" appears to be -- not a fermion distinct from the electrons and quarks -- but a charge carried by the known electrons and the quarks themselves. Similarly to the "Z" charge of electroweak theory, however, this magnetic monopole charge only manifests its interactions at sufficiently-high energy, and its interactions may not respect chiral symmetry. Calculated cross-section enhancements from magnetic monopole interactions at s=M_z^2 reduce the observed weak mixing angle for e e-bar --> mu mu-bar decays by about delta sin^2 theta_W = -.0030 relative to v v-bar --> mu mu-bar decays, and so may help account for the NuTeV anomaly. Similar, though less-pronounced reductions are calculated for e e-bar --> q q-bar.
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arxiv:hep-ph/0509223
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Top quark pair production at proton-antiproton colliders is known to exhibit a forward-backward asymmetry due to higher-order QCD effects. We explore how this asymmetry might be studied at the Fermilab Tevatron, including how the asymmetry depends on the kinematics of extra hard partons. We consider results for top quark pair events with one and two additional hard jets. We further note that a similar asymmetry, correlated with the presence of jets, arises in specific models for parton showers in Monte Carlo simulations. We conclude that the measurement of this asymmetry at the Tevatron will be challenging, but important both for our understanding of QCD and for our efforts to model it.
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arxiv:hep-ph/0509267
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We investigate three different axial-vector form factors of the nucleon, $G_A^{0}$, $G_A^3$, $G_A^8$, within the framework of the SU(3) chiral quark-soliton model, emphasizing their strangeness content. We take into account the rotational $1/N_c$ and linear strange quark ($m_s$) contributions using the symmetry-conserving SU(3) quantization and assuming isospin symmetry. The strange axial-vector form factor is also obtained and they all are discussed in the context of the parity-violating scattering of polarized electrons off the nucleon and its relevance to the strange vector form factors.
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arxiv:hep-ph/0509281
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We apply the Color Glass Condensate formalism to photon $+$ hadron production cross section in high energy deuteron (proton)-gold collisions at RHIC. We investigate the dependence of the production cross section on the angle between the produced hadron and photon for various rapidities and transverse momenta. It is shown that the angular correlation between the produced hadron and photon is a sensitive probe of the saturation dynamics.
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arxiv:hep-ph/0509338
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We discuss the experimental requirements for a mass hierarchy measurement for $\theta_{13}=0$ using muon neutrino disappearance. We find that a specially optimized neutrino factory at $L \simeq 6 \,000 \, \mathrm{km}$ could do this measurement using extreme luminosities. In particular, we do not require charge identification for this purpose. In order to measure the mass hierarchy for more adequate luminosities, we explore the capabilities of low energy narrow band off-axis beams, which have relatively more events at low energies. We find that, in this case, the energy resolution of the detector quickly becomes the limiting factor of the measurement, and significantly affects the baseline optimization for determining the mass hierarchy.
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arxiv:hep-ph/0509359
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The presence or absense of renormalon singularities in the Borel plane is shown to be determined by the analytic properties of the Gell-Mann - Low function \beta(g) and some other functions. A constructive criterion for the absense of singularities consists in the proper behavior of the \beta function and its Borel image B(z) at infinity, \beta(g)\sim g^\alpha and B(z)\sim z^\alpha with \alpha\le 1. This criterion is probably fulfilled for the \phi^4 theory, QED and QCD, but is violated in the O(n)-symmetric sigma model with n\to\infty.
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arxiv:hep-ph/0510033
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New version of MSSM scales is discussed. In this version mu << M_{SUSY} ~ M_0 \~ M_{1/2}, where mu is the Higgsino mass, M_0 is the mass scale of sleptons and squarks, M_{1/2} is the mass scale of gaugino. Renormalization group motivation of this MSSM version is proposed. Analysis of Split Supersymmetry ideas in this case together with the Dark Matter arguments results in the statement that the formation of residual neutralino concentration occurs in the high symmetric phase of cosmological plasma. The value of Higgsino mass is estimated. The recharging process for high energy neutralinos in the neutralino-nucleus scattering is considered. There has been reported the possibility to check-up of the model predictions at modern experimental facilities NUSEL and GLAST.
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arxiv:hep-ph/0510036
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We propose a generalization of the upgraded Karl- Sehgal formula which relates baryon magnetic moments to the spin structure of constituent quarks, by adding anomalous magnetic moments of quarks. We first argue that relativistic nature of quarks inside baryons requires introduction of two kinds of magnetisms, one axial and the other tensoriel. The first one is associated with integrated quark helicity distributions (standard) and the second with integrated transversity distributions . The weight of each contribution is controlled by the combination of two parameters, xi the ratio of the quark mass to the average kinetic energy Ei and ai the quark anomalous magnetic moment. The quark anomalous magnetic moment is correlated to transversity and both are necessary ingredients in describing relativistic quarks. The proposed formula, then when confronted with baryon magnetic moments data with reasonable inputs, yields beside quark magnetic densities, anomalous magnetic moments enough large to not be ignored.
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arxiv:hep-ph/0510059
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In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically investigate models of this type, showing that either high-energy or electroweak versions of baryogenesis are possible, depending on the dynamics of the Lorentz-violating fields. In addition to the previously-studied models of spontaneous baryogenesis and quintessential baryogenesis, we identify two scenarios of interest: baryogenesis from a pseudo-Nambu-Goldstone boson with weak-scale mass and intermediate-scale baryon-number violation, and sphaleron-induced baryogenesis driven by a constant-magnitude vector with a late-time phase transition.
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arxiv:hep-ph/0510081
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The screening of magnetic Z(N)-monopoles and the associated screening length in SU(N) gauge theories are analyzed theoretically, and computed numerically in the 3d SU(2) theory. The nature of the screening excitations as well as their mass have so far remained inconclusive in the literature. Here we show that the screening mass is identical to the lowest J^{PC}_R=0^{++}_+ excitation of the Yang-Mills Hamiltonian with one compact direction with period 1/T, the subscript R referring to parity in this direction. We extend the continuum formulation to one on the lattice, and determine the transfer matrix governing the decay of the spatial monopole correlator at any finite lattice spacing. Our numerical results for SU(2) for the screening mass in the dimensionally reduced (high temperature) theory are compatible with the 0^{++} glueball mass in 3d SU(2).
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arxiv:hep-ph/0510140
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We explore the quark properties at finite temperature near but above the critical temperature of the chiral phase transition. We investigate the effects of the precursory soft mode of the phase transition on the quark dispersion relation and the spectral function. It is found that there appear novel excitation spectra of quasi-quarks and quasi-antiquarks with a three-peak structure, which are not attributed to the hard-thermal-loop approximation. We show that the new spectra originate from the mixing between a quark (anti-quark) and an anti-quark hole (quark hole) caused by a ``resonant scattering'' of the quasi-fermions with the thermally-excited soft mode which has a small but finite excitation energy.
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arxiv:hep-ph/0510167
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Basics of neutrino oscillations is discussed. Importance of time-energy uncertainty relation is stressed. Neutrino oscillations in the leading approximation and evidence for neutrino oscillations are briefly summarized.
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arxiv:hep-ph/0510175
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In this Letter we interpret the Y(4260), a state recently discovered by the BaBar Collaboration that has a mass within the range of conventional charmonium states, as having a molecular-state structure. In our scheme this molecular-like state is not constructed out of two-quark mesons, but rather out of baryons, i.e., the Y(4260) is a baryonium state. With this interpretation, the unusual measured properties of the Y(4260) are easily understood and some further peculiar decay characteristics are predicted.
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arxiv:hep-ph/0510228
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A group of transformations changing the phases of the elements of the single-particle density matrix, but leaving unchanged the predictions for identical particles concerning the momentum distributions, momentum correlations etc., is identified. Its implications for the determinations of the interaction regions from studies of Bose-Einstein correlations are discussed.
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arxiv:hep-ph/0510231
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