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We investigate symmetry breaking patterns from replicated gauge groups which generate anomaly-free and family-dependent U(1) symmetries. We discuss the extent to which these symmetries can explain the observed hierarchies of fermion masses and mixings.
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arxiv:hep-ph/0302264
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We develop the QCD description of the breakup of photons into forward dijets in small-x deep inelastic scattering off nuclei in the saturation regime. Based on the color dipole approach, we derive a multiple scattering expansion for intranuclear distortions of the jet-jet transverse momentum spectrum. A special attention is paid to the non-Abelian aspects of the propagation of color dipoles in a nuclear medium. We report a nonlinear $k_{\perp}$-factorization formula for the breakup of photons into dijets in terms of the collective Weizs\"acker-Williams (WW) glue of nuclei as defined in ref. \cite{Saturation,NSSdijet}. For hard dijets with the transverse momenta above the saturation scale the azimuthal decorrelation (acoplanarity) momentum is of the order of the nuclear saturation momentum QA. For minijets with the transverse momentum below the saturation scale the nonlinear kT-factorization predicts a complete disappearance of the jet-jet correlation. We comment on a possible relevance of the nuclear decorrelation of jets to the experimental data from the STAR-RHIC Collaboration.
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arxiv:hep-ph/0303024
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The status of lattice QCD investigations at high temperature is reviewed. After a short introduction into thermal QCD on the lattice we report on the present understanding of the phase diagram and the equation of state, in particular in presence of dynamical quarks. We continue with a discussion of various screening lengths in the plasma phase including results from dimensionally reduced QCD. This is followed by summarizing lattice data on quark number susceptibilities and spectral densities, both of which are of immediate relevance to the interpretation of heavy ion experiments. A major section is devoted to presenting simulations of QCD at small yet phenomenologically important values for the baryon density.
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arxiv:hep-ph/0303042
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We confront the generally small cross sections for gluino pair production in e^+e^- annihilation with the much larger ones in photon-photon scattering at a multi-TeV linear collider like CERN CLIC. The larger rates and the steeper rise of the cross section at threshold may allow for a precise gluino mass determination in high-energy photon-photon collisions for a wide range of squark masses and post-LEP SUSY benchmark points.
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arxiv:hep-ph/0303058
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We review the status of nu_mu-->nu_tau flavor transitions of atmospheric neutrinos in the 92 kton-year data sample collected in the first phase of the Super-Kamiokande (SK) experiment, in combination with the recent spectral data from the KEK-to-Kamioka (K2K) accelerator experiment (including 29 single-ring muon events). We consider a theoretical framework which embeds flavor oscillations plus hypothetical decoherence effects, and where both standard oscillations and pure decoherence represent limiting cases. It is found that standard oscillations provide the best description of the SK+K2K data, and that the associated mass-mixing parameters are determined at 1 sigma (and d.o.f.=1) as: Delta m^2=(2.6 +- 0.4)x10^{-3} eV^2 and sin^2(2theta)=1.00+0.00-0.05. As compared with standard oscillations, the case of pure decoherence is disfavored, although it cannot be ruled out yet. In the general case, additional decoherence effects in the nu_mu-->nu_tau channel do not improve the fit to the SK and K2K data, and upper bounds can be placed on the associated decoherence parameter. Such indications, presently dominated by SK, could be strengthened by further K2K data, provided that the current spectral features are confirmed with higher statistics. A detailed description of the statistical analysis of SK and K2K data is also given, using the so-called ``pull'' approach to systematic uncertainties.
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arxiv:hep-ph/0303064
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Different possibilities of a detection of signals from extra space dimensions at high energy colliders are reviewed.
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arxiv:hep-ph/0303090
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We consider the rare top quark decays in the framework of topcolor-assisted technicolor (TC2) model. We find that the contributions of top-pions and top-Higgs predicted by the TC2 model can enhance the SM branching ratios by as much as 6-9 orders of magnitude. i.e., in the most case, the orders of magnitude of branching ratios are $Br(t\to c g)\sim 10^{-5}$, $Br(t\to c Z)\sim 10^{-5}$, $Br(t\to c \gamma)\sim 10^{-7}$. With the reasonable values of the parameters in TC2 model, such rare top quark decays may be testable in the future experiments. So, rare top quark decays provide us a unique way to test TC2 model.
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arxiv:hep-ph/0303122
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The coupled Dyson-Schwinger equations for the gluon and ghost propagators are investigated in the Landau gauge using a two-loop improved truncation that preserves the multiplicative renormalizability of the propagators. In this truncation all diagrams contribute to the leading order infrared analysis. The infrared contributions of the nonperturbative two-loop diagrams to the gluon vacuum polarization are computed analytically, and this reveals that infrared power behaved propagator solutions only exist when the squint diagram contribution is taken into account. For small momenta the gluon and ghost dressing functions behave respectively like (p^2)^{2\kappa} and (p^2)^{-\kappa}, and the running coupling exhibits a fixed point. The values of the infrared exponent and fixed point depend on the precise details of the truncation. The coupled ghost-gluon system is solved numerically for all momenta, and the solutions have infrared behaviors consistent with the predictions of the infrared analysis. For truncation parameters chosen such that \kappa=0.5, the two-loop improved truncation is able to produce solutions for the propagators and running coupling which are in very good agreement with recent lattice simulations.
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arxiv:hep-ph/0303125
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In this paper we examine T-violating triple-product correlations (TP's) in B -> V1 V2 decays. TP's are excellent probes of physics beyond the standard model (SM) for two reasons: (i) within the SM, most TP's are expected to be tiny, and (ii) unlike direct CP asymmetries, TP's are not suppressed by the small strong phases which are expected in B decays. TP's are obtained via the angular analysis of B -> V1 V2. In a general analysis based on factorization, we demonstrate that the most promising decays for measuring TP's in the SM involve excited final-state vector mesons, and we provide estimates of such TP's. We find that there are only a handful of decays in which large TP's are possible, and the size of these TP's depends strongly on the size of nonfactorizable effects. We show that TP's which vanish in the SM can be very large in models with new physics. The measurement of a nonzero TP asymmetry in a decay where none is expected would specifically point to new physics involving large couplings to the right-handed b-quark.
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arxiv:hep-ph/0303159
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Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near the critical temporature $T_c$, baryons can be produced through the processes of quarks and diquarks forming $({1/2})^+$ baryon states. Ratios of different baryons can be estimated through this method, if such kind of QGP with diquarks can exists.
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arxiv:hep-ph/0303164
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The double meson production in ultraperipheral heavy ions collisions is addressed, focusing on the particular case of rho-J/Psi from two-photon reactions. The cross section at photon level is obtained using distinct parameterizations for the gluon distribution on the light meson. The resulting estimates for the nuclear case are presented and discussed. As a by product, we estimate the double rho production cross section using the Pomeron-exchange factorization relations.
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arxiv:hep-ph/0303172
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Recently, WMAP has measured the cosmological parameters to a much greater accuracy. We analyze the implications of this more precise measurement for supersymmetric dark matter and for the direct detection of supersymmetry at accelerators. We consider mSUGRA including also the hyperbolic branch in the radiative breaking of the electroweak symmetry. On the part of the hyperbolic branch where the lightest neutralino is dominantly a higgsino rather than being mostly a bino, the relic density constraints are satisfied by coannihilation with the next lightest neutralino and the light chargino. Including this branch the lightest neutralino mass satisfies $m_{\chi_1^0}\leq 1200$ GeV for $\tan\beta\leq 50$. Constraints of $b\to s+\gamma$ and of $g_{\mu}-2$ are also analyzed. It is shown that the neutralino-proton cross section in each case will fall within the reach of dark matter experiments. Possibility for the direct detection of supersymmetry is discussed in the allowed regions of the parameter space consistent with WMAP constraints. A brief discussion of the hyperbolic branch and focus point region (HB/FP) is also given.
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arxiv:hep-ph/0303201
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We study possible saturation effects in the total cross-section describing interaction of ultrahigh energy neutrinos with nucleons. This analysis is performed within the two approaches, i.e. within the Golec-Biernat W\"usthoff saturation model and within the scheme unifying the DGLAP and BFKL dynamics incorporating non-linear screening effects which follow from the Balitzki-Kovchegov equation. The structure functions in both approaches are constrained by HERA data. It is found that screening effects affect extrapolation of the neutrino-nucleon total cross-sections to ultrahigh neutrino energies $E_{\nu}$ and reduce their magnitude by a factor equal to about 2 at $E_{\nu} \sim 10^{12}GeV$. This reduction becomes amplified by nuclear shadowing in the case of the neutrino-nucleus cross-sections and approximate estimate of this effect is performed.
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arxiv:hep-ph/0303209
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We present a possible supersymmetric solution to the discrepancy between the observed mixing CP asymmetries in B -> \phi K_S and B -> \eta' K_S. We show that due to the different parity in the final states of these processes, their supersymmetric contributions from the R-sector have an opposite sign, which naturally explain the large deviation between S_{\phi K_S} and S_{\eta' K_S}. We also consider the proposed mechanisms to solve the puzzle of the observed large branching ratio of B -> \eta' K and study their impact on S_{eta' K_S}.
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arxiv:hep-ph/0303214
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We show how the well studied $\gamma\gamma$ inclusive Higgs signal can be used at the Large Hadron Collider to test Gauge Mediated Supersymmetry Breaking scenarios in which a rather heavy Higgs boson decays into two light neutralinos, the latter yielding two photons and missing (transverse) energy
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arxiv:hep-ph/0303251
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In the context of a SUSY GUT inspired MSSM version, the low energy consequences of the asymptotic $b-\tau$ Yukawa coupling Unification are examined, under the assumption of universal or non-universal boundary conditions for the gaugino and sfermion masses. Gaugino non-universality is applied, so that the SUSY corrections to $b$-quark mass can be reconciled with the present experimental data on muon anomalous magnetic moment. Restrictions on the parameter space, originating from the Cold Dark Matter abundance in the universe, the inclusive branching ratio of $b\to s\gamma$ and the accelerator data are, also, investigated and the scalar neutralino-proton cross section is calculated. In the case of a bino-like LSP and universal boundary conditions for the sfermion masses, the constraints, arising from the Cold Dark Matter and ${\rm BR}(b \to s\gamma)$ can be simultaneously satisfied, mainly thanks to the $A$-pole effect or the neutralino-stau coannihilations. In addition, sfermion mass non-universality provides the possibility of new coannihilation phenomena (neutralino-sbottom or neutralino-tau sneutrino-stau), which facilitate the simultaneous satisfaction of all the above requirements. In both cases above, the neutralino abundance can essentially decrease for a W-ino or higgsino like LSP creating regions of parameter space with additional neutralino-chargino and/or heavier neutralino coannihilations. The neutralino-sbottom mass proximity significantly ameliorates the detectability of LSP.
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arxiv:hep-ph/0304047
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The field responsible for the cosmological curvature perturbations generated during a stage of primordial inflation might be the ``curvaton'', a field different from the inflaton field. To keep the effective mass of the curvaton small enough compared to the Hubble rate during inflation one may not invoke supersymmetry since the latter is broken by the vacuum energy density. In this paper we propose the idea that the curvaton is a pseudo Nambu-Goldstone boson (PNGB) so that its potential and mass vanish in the limit of unbroken symmetry. We give a general framework within which PNGB curvaton candidates should be explored. Then we explore various possibilities, including the case where the curvaton can be identified with the extra-component of a gauge field in a compactified five-dimensional theory (a Wilson line), where it comes from a Little-Higgs mechanism, and where it is a string axion so that supersymmetry is essential.
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arxiv:hep-ph/0304050
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The observed neutrino oscillation data might be explained by new physics at a TeV scale, which is testable in the future experiments. Among various possibilities, the low-energy Higgs triplet model is a prime candidate of such new physics since it predicts clean signatures of lepton flavor violating processes directly related to the neutrino masses and mixing. It is discussed how various neutrino mass patterns can be discriminated by examining the lepton flavor violating decays of charged leptons as well as the collider signatures of a doubly charged Higgs boson in the model.
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arxiv:hep-ph/0304069
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In this work we will study the polarizations of both leptons ($\tau$) in the decay channel $B\to K^* \tau^- \tau^+$. In the case of the dileptonic inclusive decay $B\to K^* \ell^- \ell^+$, where apart from the polarization asymmetries of single lepton $\ell$, one can also observe the polarization asymmetries of both leptons simultaneously. If this sort of measurement is possible then we can have, apart from decay rate, FB asymmetry and the six single lepton polarization asymmetries (three each for $\ell^-$ and $\ell^+$), nine more double polarization asymmetries. This will give us a very useful tool in more strict testing of SM and the physics beyond. We discuss the double polarization asymmetries of $\tau$ leptons in the decay mode $B\to K^* \tau^- \tau^+$ within the SM and the Minimal Supersymmetric extensions of it.
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arxiv:hep-ph/0304084
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Quark model with potentials derived from QCD, including the quark-diquark model for excited hadrons gives mass formulae in very good agreement with experiment and goes a long way in explaining the approximate symmetries and supersymmetries of the hadronic spectrum, including the symmetry breaking mechanism.
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arxiv:hep-ph/0304133
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We fix exactly and uniquely the infrared structure of the full gluon propagator in QCD, not solving explicitly the corresponding dynamical equation of motion. By construction, this structure is an infinite sum over all possible severe (i.e., more singular than $1/q^2$) infrared singularities. It reflects the zero momentum modes enhancement effect in the true QCD vacuum, which is due to the self-interaction of massless gluons. It existence automatically exhibits a characteristic mass (the so-called mass gap). It is responsible for the scale of nonperturbative dynamics in the true QCD ground state. The theory of distributions, complemented by the dimensional regularization method, allows one to put the severe infrared singularities under the firm mathematical control. By an infrared renormalization of a mass gap only, the infrared structure of the full gluon propagator is exactly reduced to the simplest severe infrared singularity, the famous $(q^2)^{-2}$. Thus we have exactly established the interaction between quarks (concerning its pure gluon (i.e., nonlinear) contribution) up to its unimportant perturbative part. This also makes it possible for the first time to formulate the gluon confinement criterion and intrinsically nonperturbative phase in QCD in a manifestly gauge-invariant ways.
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arxiv:hep-ph/0304163
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We present a scenario in which Yukawa-like R-parity violating (RPV) couplings are naturally suppressed. In our framework, RPV is assumed to originate from the SUSY breaking mechanism and then transmitted into the SUSY Lagrangian only through soft SUSY breaking operators in the scalar potential. The RPV Yukawa-like operators of the superpotential, conventionally parametrized by the couplings \lambda, \lambda' and \lambda'', are then generated through loops containing the SUSY scalars, the gauginos and the soft RPV interactions and are, therefore, manifest as effective operators with a typical strength of order 10^{-3}.
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arxiv:hep-ph/0304170
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A definition of the rho parameter based on the Higgs couplings with the gauge bosons, rho_h= g_{hWW}}/c^2_W g_{hZZ}, is proposed as a new probe into the origin of the mechanism of electroweak symmetry breaking. While $\rho_h=1$ holds in the SM, deviations from one are predicted in models with extended Higgs sector. We derive a general expresion of rho_h for a model with arbitrary Higgs multiplets, and discuss its size within the context of specific models with Higgs triplets, including the ``Little Higgs'' models recently proposed. We find the even for Higgs models that incorporate the custodial symmetry to make rho=1, one could have rho_h\neq 1, which could be tested at the level of a few percent, with the precision Higgs meassurements expected at the NLC.
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arxiv:hep-ph/0304212
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We study the inclusive semileptonic rare decay $b \to s l^+ l^-$ in minimal supergravity model (mSUGRA). If tan$\beta$ is large, down-type quark mass matrices and their Yukawa couplings cannot be diagonalized at the same basis. This induces the flavor violating neutral Higgs boson couplings. These couplings contribute significantly to decay $b \to s mu^+ mu^-$ and $b \to s tau^+ tau^-$, but negligible to $b \to s e^+ e^-$ decay because of its negligible $m_e$ mass. The ratio $R \equiv B(b \to s mu^+ mu^-)/ B(b \to s e^+ e^-)$ can be very different from its corresponding value in the Standard Model. We find that part of parameter space can accommodate a large R value, and that maximum R value can be larger than 2. We also present our results in $b \to s tau^+ tau^-$ decay channel. Although it can be not detected now, it is potentially a new channel for the future observation of new physics.
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arxiv:hep-ph/0304248
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We demonstrate that under the "symmetric zero texture" with minimal Majorana mass matrix, neutrino masses and mixing angles are expressed in terms of up-quark masses, $m_t,m_c,m_u$. This provides interesting relations among neutrino mixing angles and up-type quark masses. Especially we predict $|U_{e3}| \leq 0.11$ even if we include the small mixing effects coming from charged lepton side. Also absolute masses of three neutrinos are predicted almost uniquely. This is quite in contrast to the case where bi-large mixings come from the charged lepton sector with non-symmetric charged lepton mass matrix.
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arxiv:hep-ph/0305016
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During inflation, primordial energy density fluctuations are created from approximate de Sitter vacuum quantum fluctuations redshifted out of the horizon after which they are frozen as perturbations in the background curvature. In this paper we demonstrate that there exists an intrinsic theoretical uncertainty in the inflationary predictions for the curvature perturbations due to the failure of the well known prescriptions to specify the vacuum uniquely. Specifically, we show that the two often used prescriptions for defining the initial vacuum state -- the Bunch-Davies prescription and the adiabatic vacuum prescription (even if the adiabaticity order to which the vacuum is specified is infinity) -- fail to specify the vacuum uniquely in generic inflationary spacetimes in which the total duration of inflation is finite. This conclusion holds despite the absence of any trans-Planckian effects or effective field theory cutoff related effects. We quantify the uncertainty which is applicable to slow roll inflationary scenarios as well as for general FRW spacetimes and find that the uncertainty is generically small. This uncertainty should be treated as a minimal uncertainty that underlies all curvature perturbation calculations.
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arxiv:hep-ph/0305074
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The possibility of achieving a gauge coupling grand unification by increasing the QCD degrees of freedom at higher energies is investigated. When confronted with precision low-energy data, the generic weak-mixing angle relation sin^2(theta_W) = N/2(N+1) requires N=7 colors at the GUT scale M_U ~ 10^17 GeV. With the exclusive addition of light Higgs doublets to the standard model particle content, such a unification may also occur if N=5 at M_U ~ 10^16 GeV.
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arxiv:hep-ph/0305092
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The neutron charge radius is studied within a light-front model with different spin coupling schemes and wave functions. The cancellation of the contributions from the Foldy term and Dirac form factor to the neutron charge form factor is verified for large nucleon sizes and it is independent of the detailed form of quark spin coupling and wave function. For the physical nucleon our results for the contribution of the Dirac form factor to the neutron radius are insensitive to the form of the wave function while they strongly depend on the quark spin coupling scheme.
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arxiv:hep-ph/0305120
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Models with extra space dimensions naturally provide for the existence of fermions that propagate in them. These are seen in 4D as an infinite tower of sterile neutrinos possibly mixed with the Standard Model ones. We consider the effect of such a mixing in the context of core collapse supernova physics. We show that the potentially dramatic modifications to the supernova evolution (commonly believed to set very strong bounds on the parameters of the extra dimensions) are prevented by a mechanism of feedback, so that much weaker bounds need to be imposed. Nevertheless, the supernova core evolution is significantly modified. We discuss the compatibility with the SN1987a signal and we analyse the distinctive signatures of the neutrino signal on Earth.
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arxiv:hep-ph/0305141
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The dimensionally regularized massless on-shell planar triple box Feynman diagram with powers of propagators equal to one is analytically evaluated for general values of the Mandelstam variables s and t in a Laurent expansion in the parameter \ep=(4-d)/2 of dimensional regularization up to a finite part. An explicit result is expressed in terms of harmonic polylogarithms, with parameters 0 and 1, up to the sixth order. The evaluation is based on the method of Feynman parameters and multiple Mellin-Barnes representation. The same technique can be quite similarly applied to planar triple boxes with any numerators and integer powers of the propagators.
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arxiv:hep-ph/0305142
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We update a recent work devoted to resolve the degeneracies that appear in the simultaneous extraction of $\theta_{13}$ and $\delta$ at future Neutrino Factories (NF, that exploit the \emph{golden} channels, i.e. $\nu_e\to\nu_\mu$ ($\bar{\nu}_e\to\bar{\nu}_\mu$)) and Superbeam experiments (SB, that measure the $\nu_\mu\to\nu_e$ ($\bar{\nu}_\mu\to\bar{\nu}_e$) transitions). We consider the neutrino fluxes obtained with a new optics design for the CERN-SPL SB and assume the solar parameters within the LMA-I and the LMA-II regions indicated by recent KamLAND data. The dangerous fake solution associated with the $\theta_{23}$-ambiguity remains after the combination of data from these two facilities: in this perspective, we analyze the impact of the NF-\emph{silver} channels, i.e. $\nu_e\to\nu_\tau$ ($\bar{\nu}_e\to\bar{\nu}_\tau$). The combination of data from these three experiments -NF(\emph{golden} and \emph{silver} channels) plus SPL SB- can discover leptonic CP violation for values of $\theta_{13}\ge 1^{\circ}$.
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arxiv:hep-ph/0305146
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We present an innovative method to resum infrared and collinear logarithms appearing in distributions of jet observables in QCD. The method, based on a general master formula with applicability conditions, allows resummations at next-to-leading logarithmic accuracy in an automated way. As a sample application we present resummed results in hadronic dijet events.
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arxiv:hep-ph/0305163
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A phenomenological description of diffractive dijet hadroproduction via double Pomeron exchange is presented. This description is based on a modified version of the Ingelman-Schlein model which includes the evolution of the Pomeron structure function and corrections regarding rapidity gap suppression effects. The same quark-dominant Pomeron structure function employed in a previous report to describe diffractive dijet and W production via single Pomeron processes is shown here to yield results consistent with the available data for double Pomeron processes as well.
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arxiv:hep-ph/0305186
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We stress that massive neutrinos may be Majorana particles even if the effective mass of the neutrinoless double beta decay m_ee vanishes. We show that current neutrino oscillation data do allow m_ee = 0 to hold, if the Majorana CP-violating phases lie in two specific regions. Strong constraints on three neutrino masses can then be obtained. We find that the neutrino mass spectrum performs a normal hierarchy: m_1 < m_2 < m_3. A possible texture of the neutrino mass matrix is also illustrated under the m_ee = 0 condition.
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arxiv:hep-ph/0305195
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Semi-leptonic and leptonic decays of B-mesons are important probes for testing SM and theories beyond it because of their relative cleanliness and far less theoretical uncertainties. In semi-leptonic decays based on quark level transition $b \to s \tau^+ \tau^-$ apart from branching ratio one can study many other (possible) observables associated with final state leptons like, lepton pair Forward Backward asymmetry, lepton polarization asymmetries etc. But as proposed recently if we can tag the B-meson than one can measure the polarization asymmetries of both the leptons. Here we will study the polarization asymmetries of both the final state leptons in SM and Minimal Supersymmetric Extension (MSSM) to it.
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arxiv:hep-ph/0305242
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We present a pedagogical review of neutrino physics. In the first lecture we describe the theoretical motivation for neutrino masses, and explain how neutrino flavor oscillation experiments can probe neutrino masses. In the second lecture we review the experimental data, and show that it is best explained if neutrinos are massive. In the third lecture we explain what are the theoretical implications of the data, in particular, what are the challenges they impose on models of physics beyond the SM. We give examples of theoretical models that cope with some of these challenges.
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arxiv:hep-ph/0305245
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We study precision electroweak constraints on the close cousin of the Littlest Higgs, the SU(6)/Sp(6) model. We identify a near-oblique limit in which the heavy W' and B' decouple from the light fermions, and then calculate oblique corrections, including one-loop contributions from the extended top sector and the two Higgs doublets. We find regions of parameter space that give acceptably small precision electroweak corrections and only mild fine tuning in the Higgs potential, and also find that the mass of the lightest Higgs boson is relatively unconstrained by precision electroweak data. The fermions from the extended top sector can be as light as 1 TeV, and the W' can be as light as 1.8 TeV. We include an independent breaking scale for the B', which can still have a mass as low as a few hundred GeV.
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arxiv:hep-ph/0305275
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In hybrid inflation and running mass inflation models it is possible that the inflaton field will fragment into non-topological solitons, resulting in a highly inhomogeneous post-inflation era prior to reheating. In supersymmetric models with a conventional homogeneous post-inflation era, the dynamics of flat direction scalars are determined by cH^{2} corrections to the mass squared terms, coming from the energy density of the Universe combined with Planck-scale suppressed interactions. Here we reconsider the cH^{2} corrections for a Universe dominated by inflatonic non-topological solitons. We show that the dynamics in this case are typically equivalent to the case c = 0, even in the vicinity of the non-topological solitons. Thus Affleck-Dine baryogenesis will proceed as in the original c = 0 Affleck-Dine scenario.
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arxiv:hep-ph/0305306
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We argue that the amount of baryon stopping observed in the central rapidity region of heavy ion collisions at RHIC is proportional to the nuclear valence quark distributions at small x. By generalizing Mueller's dipole model to describe Reggeons we construct a non-linear evolution equation for the valence quark distributions at small x in the leading double-logarithmic approximation. The equation includes the effects of gluon saturation in it. The solution of the evolution equation gives a valence quark distribution function $dn_{val}/dy \sim e^{-(0.4\div0.5) y}$. We show that this y-dependence as well as the predictions of Regge theory are consistent with the net-proton rapidity distribution reported by BRAHMS.
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arxiv:hep-ph/0305332
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Under the assumptions that 1) the quark/lepton mass matrices take Froggatt-Nielsen's factorized power form \lambda^{\psi_i+\psi_j} with anomalous U(1) charges \psi_i, and 2) the U(1) charges \psi_i respect the SU(5) GUT structure, we show that the quark mass data necessarily implies the large 2-3 mixing in the MNS mixing matrix U_{MNS}. If we further add the data of the mass squared difference ratio of solar and atmospheric neutrinos, then, it implies that the 1-2 mixing in U_{MNS} is also large, so explaining the bi-large mixing. This analysis also gives a prediction that U_{e3}\equiv(U_{\rm MNS})_{13} should be of order \lambda \sim (0.1 - 0.5).
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arxiv:hep-ph/0306035
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Light Higgs bosons (h^0) with a mass below 60 GeV may have escaped detection at LEP due to a suppressed cross-section for e^+e^-\to Zh^0. Their discovery is also problematic in standard search channels at the Tevatron Run II and LHC. Such a h^0 can arise in the two Higgs doublet model (2HDM) and in the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violating phases. We propose the mechanism p\bar p \to H^\pm h^0 which offers cross-sections of up to 500 fb in the 2HDM, or up to 100 fb in the MSSM. The possibility of a large branching ratio for H^\pm\to h^0W^\pm would give rise to the non-standard signature h^0h^0W^\pm which might facilitate detection.
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arxiv:hep-ph/0306045
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In the paper the thermal energy transfer for elementary particles is described. The quantum heat transport equation is obtained. It is shown that for thermal excitation of the order of the relaxation time the excited matter response is quantized on the different levels (atomic, nuclear, quark) with quantum thermal energy equal E^{atomic}=9 eV, E^(nuclear)=7 MeV and E^{quark}=139 MeV. As the result the quantum for the heating process of nucleons is the pi-meson (consisting of the two quarks). Keywords: Heat quanta; Quantum heat transport; Quantum diffusion coefficient.
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arxiv:hep-ph/0306046
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We describe in detail the method we have used to determine the CKM angles gamma, alpha and beta using flavour symmetries between non-leptonic B decays. This method is valid in the context of the SM but also in presence of New Physics not affecting the amplitudes.
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arxiv:hep-ph/0306058
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The arbitrariness in how the logarithm is defined within the QCD series for the inclusive electroproduction cross-section is shown to affect the summation to all orders in $\alpha_s$ of leading and successively-subleading logarithms within that perturbative series, even though such summations largely eliminate the residual dependence of the original series on the arbitrary renormalization scale $\mu$. However, given that the original (unimproved) series is known to third-order in $\alpha_s(\mu)$, this logarithm ambiguity is shown not to enter the optimally improved summation-of-logarithms series until the term fourth-order in $\alpha_s(s)$, where $s$ is the physical center-of-mass energy squared. Consequently, the ambiguity in how the logarithm is defined is absorbable in the uncertainty associated with truncating the original perturbative series after its calculationally known terms.
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arxiv:hep-ph/0306064
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We discuss the constraints induced by the algebra of the Poincare' generators on non-relativistic effective field theories. In the first part we derive some relations among the matching coefficients of the HQET (and NRQCD), which have been formerly obtained by use of reparametrization invariance. In the second part we obtain new constraints on the matching coefficients of pNRQCD.
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arxiv:hep-ph/0306107
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In the presence of strong magnetic field reported to have been observed on the surface of some neutron stars and on what are called Magnetars, a host of physical phenomenon from the birth of a neutron star to free streaming neutrino cooling phase will be modified. In this review I will discuss the effect of magnetic field on the equation of state of high density nuclear matter by including the anomalous magnetic moment of the nucleons into consideration. I would then go over to discuss the neutrino interaction processes in strong as well as in weak magnetic fields. The neutrino processes are important in studying the propagation of neutrinos and in studying the energy loss, Their study is a prerequisite for the understanding of actual dynamics of supernova explosion and on the stabilization of radial pulsation modes through the effect on bulk viscosity. The anisotropy introduced in the neutrino emission and through the modification of the shape of the neutrino sphere may explain the observed pulsar kicks.
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arxiv:hep-ph/0306116
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I discuss what we have learned about Gamma-Ray Bursts (GRBs) by studying their `afterglows', and how these are interpreted in the generally-accepted `fireball' model of GRBs, as well as in the generally-unaccepted `cannonball' model of the same phenomena. The interpretation of GRBs is a good example around which to frame a discussion of the different approaches to science found in various fields, such as high-energy physics (HEP), high-energy astrophysics, or even the deciphering of ancient languages. I use this example to draw conclusions on `post-academic' science, and on the current status of European HEP.
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arxiv:hep-ph/0306140
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We give a simple and straightforward procedure of how to construct an effective meson Lagrangian from QCD Lagrangian. We integrate the methods of Gasser, Leutwyler, Alkofer and Reinhardt and use the derivative expansion scheme to derive the low energy effective Lagrangian for meson fields to $O(p^4)$. In this paper, why the meson particle can be treated as the goldstone mode is very clear. In our calculation the result in $O(p^2)$ is the same as in the chiral perturbation theory, but the result in $O(p^4)$ is different from that in literature. We will discuss the discrepancies and give some remarks on our result.
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arxiv:hep-ph/0306143
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We investigate the importance of final state interactions in weak nonleptonic hyperon decays within a relativistic chiral unitary approach based on coupled channels. The effective potentials for meson-baryon scattering are derived from a chiral effective Lagrangian and iterated in a Bethe-Salpeter equation, which generates the low lying baryon resonances dynamically. The inclusion of final state interactions decreases the discrepancy between theory and experiment for both s and p waves. Our study indicates that contributions from higher order terms of the weak effective Lagrangian may play an important role in these decays.
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arxiv:hep-ph/0306175
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The Nielsen - Olesen flux tube in the SU(2) Yang - Mills - Higgs theory dressed with the color electric $E^a_{\rho,\phi}$ and magnetic $H^a_{\rho,\phi}$ fields is derived. On the next step it is argued that this flux tube can be considered as a result of the nonperturbatuve analytical calculations in the SU(3) quantum theory.
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arxiv:hep-ph/0306203
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Recently, it has been observed that the non-Abelian action associated with lattice monopoles and vortices is ultraviolet divergent, at least at presently available lattices. On the other hand, the total length of the monopole trajectories and area of the vortices scale in physical units. Coexistence of the two different scales, infrared and ultraviolet, for the same vacuum fluctuations represents a fine tuning. To check consistency of the newly emerging picture of non--perturbative fluctuations we consider constraints from the continuum theory on the ultraviolet behaviour of the monopoles and vortices. The constraints turn to be satisfied by the data in a highly non-trivial way. Namely, it is crucial that the monopoles populate not the whole of the four dimensional space but a two-dimensional subspace of it.
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arxiv:hep-ph/0306262
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In this talk I describe how to discover or rule out the existence of W^{prime} bosons at the CERN Large Hadron Collider as a function of arbitrary couplings and W^{prime} masses. If W^{prime} bosons are not found, I demonstrate the 95% confidence-level exclusions that can be reached for several classes of models. In particular, W^{prime} bosons in the entire reasonable parameter space of Little Higgs models can be discovered or excluded in 1 year at the LHC.
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arxiv:hep-ph/0306266
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Some theoretical aspects of $B$ physics are reviewed. These include a brief recapitulation of information on weak quark transitions as described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix, a description of CP asymmetries in $B$ decays to CP eigenstates and self-tagging modes, a discussion of final-state phases in $B$ and charm decays, some topics on $B_s$ properties and decays, the prospects for unusual excited $B$ states opened by discovery of some narrow $c \bar s$ resonances, and the prospects for seeing the heavier $Q=1/3$ quarks predicted in some extended grand unified theories.
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arxiv:hep-ph/0306284
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The status of QCD phenomena and open problems are reviewed
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arxiv:hep-ph/0306287
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The $K^-/K^+$ ratio in heavy-ion collisions at GSI energies is studied including the properties of the participating hadrons in hot and dense matter. The determination of the temperature and chemical potential at freeze-out conditions compatible with the ratio $K^-/K^+$ is very delicate, and depends on the approach adopted for the antikaon self-energy. Three approaches for the $K^-$ self-energy are considered: non-interacting $K^-$, on-shell self-energy and single-particle spectral density. With respect to the on-shell approach, the use of an energy dependent $\bar{K}$ spectral density, including both s- and p-wave components of the $\bar{K}N$ interaction, lowers considerably the freeze-out temperature and gives rise to the "broad-band equilibration" advocated by Brown, Rho and Song.
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arxiv:hep-ph/0307009
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We analyse the CP asymmetry of the B -> phi K_S and B -> eta' K_S processes in general supersymmetric models. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi K_S processes observed by Belle and BABAR experiments. We also show that due to the different parity in the final states of these processes, their supersymmetric contributions from the R-sector have an opposite sign, which naturally explain the large deviation between their asymmetries.
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arxiv:hep-ph/0307024
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On the basis of a next-to-leading-order calculation in chiral perturbation theory, the first complete analysis of isospin breaking for direct CP violation in K^0 -> 2 pi decays is performed. We find a destructive interference between three different sources of isospin violation in the CP violation parameter epsilon'. Within the uncertainties of large-N_c estimates for the low-energy constants, the isospin violating correction for epsilon' is below 15 %.
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arxiv:hep-ph/0307030
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We present the general expressions for the resummation, up to next-to-leading logarithmic accuracy, of Sudakov-type logarithms in processes with an arbirtrary number of hard-scattering partons. These results document the formulae used by the authors in several previous phenomenological studies. The resummation formulae presented here, which are valid for phase-space factorizable observables, determine the resummation correction in a process-independent fashion. All process dependence is encoded in the colour and flavour structure of the leading order and virtual one-loop amplitudes, and in Sudakov weights associated to the cross section kinematics. We explicitly illustrate the application to the case of Drell--Yan and prompt-photon production.
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arxiv:hep-ph/0307035
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We demonstrate that next generation high-energy neutrino telescopes may reveal the existence of interactions induced by standard model electroweak instantons. The energy spectrum, the angular distribution, and the quark and lepton multiplicity of events in the detector each provide signatures which can indicate the presence of these interactions. High-energy neutrino telescopes may be capable of searching for signals at energies far beyond the reach of the next generation colliders.
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arxiv:hep-ph/0307120
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A brief review is given of the developments of mSUGRA and its extensions since the formulation of these models in 1982. Future directions and prospects are also discussed.
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arxiv:hep-ph/0307123
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In supersymmetric see-saw model, the large flavor mixings of sleptons induce the lepton flavor violating (LFV) interactions $\ell_I \bar\ell_J V$ ($V=\gamma, Z$), which give rise to various LFV processes. In this work we examine the induced LFV decays $Z\to\ell_I \bar\ell_J$. Subject to the constraints from the existing neutrino oscillation data and the experimental bounds on the decays $\ell_J\to\ell_I\gamma$, these LFV $Z$-decays are found to be sizable, among which the largest-rate channel $Z\to \tau \bar{\mu}$ can ocuur with a branching ratio of $10^{-8}$ and may be accessible at the LHC or GiagZ experiment.
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arxiv:hep-ph/0307126
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We discuss recent developments in neutrino physics and focus, in particular, on neutrino oscillations and matter effects of three light active neutrinos. Moreover, we discuss the difference between Dirac and Majorana neutrinos, neutrinoless $\beta\beta$-decay, absolute neutrino masses and electromagnetic moments. Basic mechanisms and a few models for neutrino masses and mixing are also presented.
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arxiv:hep-ph/0307149
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The elastic neutron form factors $G_{En}$ and $G_{Mn}$ are calculated in a GPD framework using GPDs obtained from fits to proton elastic form factors $G_{Ep}$ and $G_{Mp}$, and isospin symmetry, with no further changes in parameters. The results for $G_{En}$ are in good agreement with existing data, while those for $G_{Mn}$ are fair. The calculations predict the form factors for future measurements at higher $Q^2$.
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arxiv:hep-ph/0307162
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We calculate the lepton electric dipole moments in a class of supersymmetric seesaw models and explore the possibility that they may provide a way to probe some of the CP violating phases responsible for the origin of matter via leptogenesis. We show that in models where the right handed neutrino masses, $M_R$ arise from the breaking of local B-L symmetry by a Higgs field with B-L=2, some of the leptogenesis phases can lead to enhancement of the lepton dipole moments compared to the prediction of models where $M_R$ is either directly put in by hand or is a consequence of a higher dimensional operator.
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arxiv:hep-ph/0307163
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The most general amplitude for the radiative pion decay pi -> e nu gamma including terms beyond V-A theory is considered. The experimental constraints on the decay amplitude components are discussed. A model independent presentation of the results of high statistics and high resolution experiments is suggested.
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arxiv:hep-ph/0307166
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The non-linear evolution of dense partonic systems has been suggested as one of the novel physics mechanisms relevant to the dynamics of hadron-nucleus and nucleus-nucleus collisions at collider energies. Here we study to what extent the description of Cronin enhancement in the framework of this non-linear evolution is consistent with the recent observation in 200 AGeV d--Au collisions at the Relativistic Heavy Ion Collider. We solve the Balitsky-Kovchegov evolution equation numerically for several initial conditions encoding Cronin enhancement. We find that the properly normalized nuclear gluon distribution is suppressed at all momenta relative to that of a single nucleon. Calculating the resulting spectrum of produced gluons in p-A and A-A collisions, we establish that the nonlinear QCD evolution is unable to generate a Cronin type enhancement, and that it quickly erases any such enhancement which may be present at lower energies.
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arxiv:hep-ph/0307179
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We study deeply virtual Compton scattering and deep exclusive meson electroproduction on a deuteron target. We model the Generalized Quark Distributions in the deuteron by using the impulse approximation for the lowest Fock-space state on the light-cone. We study the properties of the resulting GPDs, and verify that sum rules violations are quite small in the impulse approximation. Numerical predictions are given for the unpolarized cross sections and polarization asymmetries for the kinematical regimes relevant for JLab experiments and for HERMES at HERA. We conclude that the signal of coherent scattering on the deuteron is comparable to the one on the proton at least for low momentum transfer, providing support to the feasibility of the experiments. The short distance structure of the deuteron may thus be scrutinized in the near future.
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arxiv:hep-ph/0307231
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Integral and derivative dispersion relations (DR) are considered for the $pp$ and $\bar pp$ forward scattering amplitudes. A new representation for the derivative DR, valid at lower energies than the standard one, is obtained. The data on the total cross sections of $pp (\bar pp)$ interaction as well as those on the ratio of the real part to the imaginary part of the forward amplitude are analyzed within various forms of the DR and high-energy Regge models. It is shown that three models for the pomeron, simple pole with intercept larger than one, triple pole pomeron and double pole pomeron (both with intercept equal to one) lead to practically equivalent descriptions of the data at $\sqrt{s}>5$ GeV. It is also shown that the low-energy part of the dispersion integral (from the two-proton threshold up to $\sqrt{s}=5$ GeV) allows one to reproduce well the data on $\rho$ at lower energies without additional free parameters
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arxiv:hep-ph/0307254
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In understanding the world of matter, the introduction of symmetry principles following experimentation or using the predictive power of symmetry principles to guide experimentation is most profound. The conservation of energy, linear momentum, angular momentum, charge, and CPT involve fundamental symmetries. All other conservation laws are valid within a restricted subspace of the four interactions: the strong, the electromagnetic, the weak, and the gravitational interaction. In this paper comments are made regarding parity violation in hadronic systems, charge symmetry breaking in two nucleon and few nucleon systems, and time-reversal-invariance in hadronic systems.
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arxiv:hep-ph/0307285
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We investigate scalar and spinor field theories in a constant magnetic field at finite temperature and chemical potential. In an external constant magnetic field the exact solution of the two-point Green functions are obtained by using the Fock-Schwinger proper-time formalism. We extend it to the thermal field theory and find the expressions of the Green functions exactly for the temperature, the chemical potential and the magnetic field. For practical calculations the contour of the proper-time integral is carefully selected. The physical contour is discussed in a constant magnetic field at finite temperature and chemical potential. As an example, behavior of the vacuum self-energy is numerically evaluated for the free scalar and spinor fields.
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arxiv:hep-ph/0307289
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We show that a hydrodynamical model with continuous particle emission instead of sudden freeze out may explain both the observed strange particle and pion abundances and transverse mass spectra for light projectile at SPS energy. We found that the observed enhancement of pion production corresponds, within the context of continuous emission, to the maximal entropy production.
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arxiv:hep-ph/0307306
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I describe the surrounding landscape on the road to the CERN Large Hadron Collider. I revisit the milestones of hadron-collider physics, and from them draw lessons for the future. I recall the primary motivation for the journey - understanding the mechanism of electroweak symmetry breaking - and speculate that even greater discoveries may await us. I review the physics that we know beyond the standard model - dark matter, dark energy, and neutrino masses - and discuss the status of grand-unified theories. I list the reasons why the Higgs boson is central to the standard model as well as to physics beyond the standard model.
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arxiv:hep-ph/0307324
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We calculate the decay couplings and first two Gegenbauer moments of the leading twist light-cone distribution amplitudes of K and K* from QCD sum rules, including NLO perturbative effects.
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arxiv:hep-ph/0307337
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It is explained why excessive mu to e gamma can be a problem in SUSY GUT see-saw models of neutrino mass, and ways that this problem might be avoided are discussed.
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arxiv:hep-ph/0307372
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We propose an inflation model in supergravity, in which chaotic and hybrid inflation occurs successively, followed by new inflation. During hybrid inflation, adiabatic fluctuations with a running spectral index with $\ns >1$ on a large scale and $\ns <1$ on a smaller scale are generated, as favored by recent results of the first year Wilkinson Microwave Anisotropy Probe. The initial condition of new inflation is also set dynamically during hybrid inflation, and its duration and the amplitude of density fluctuations take appropriate values to help early star formation to realize early reionization.
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arxiv:hep-ph/0307373
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We study the Higgs-boson decays h0 -> b \bar{b}, h0 -> \gamma \gamma and h0 -> \gamma Z within the framework of the Two Higgs Doublet Model (THDM) in the context of the decoupling regime, together with tree level unitarity constraints. We show that when the light CP-even Higgs boson of the THDM mimics the Standard-Model Higgs boson, not only the one-loop effects to h0 -> {\gamma \gamma ,\gamma Z} but also the one-loop contribution to h0 -> b \bar{b} can be used to distinguish between THDM and SM. The size of the quantum effects in h0 -> b \bar{b} are of the same order as in h0 -> {\gamma \gamma ,\gamma Z} and can reach 25% in both cases.
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arxiv:hep-ph/0307391
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The Standard Model provides an excellent description of the observables measured at high energy lepton and hadron colliders. However, measurements of the forward-backward asymmetry of the bottom quark at LEP suggest that the effective coupling of the right-handed bottom quark to the neutral weak gauge boson is significantly different from the value predicted by the Standard Model. Such a large discrepancy may be the result of a mixing of the bottom quark with heavy mirror fermions with masses of the order of the weak scale. To be consistent with the precision electroweak data, the minimal extension of the Standard Model requires the presence of vector-like pairs of SU(2) doublet and singlet quarks. In this article, we show that such an extension of the Standard Model is consistent with the unification of gauge couplings and leads to a very rich phenomenology at the Tevatron, the B-factories and the LHC. In particular, if the Higgs boson mass lies in the range 120 GeV $\simlt m_h \simlt 180$ GeV, we show that Run II of the Tevatron collider with 4--8 fb$^{-1}$ of integrated luminosity will have the potential to discover the heavy quarks, while observing a 3-$\sigma$ evidence of the Higgs boson in most of the parameter space. We also discuss the effects on the time dependent CP-asymmetry in $B \to \phi K_s$ decays.
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arxiv:hep-ph/0308001
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The neutrino sector in a left-right extension of the Standard Model depends on how SU(2)_R is broken. I list all possible scenarios, including the ones where the Majorana nu_R mass is naturally much smaller than the SU(2)_R breaking scale, which is desirable for generating the proper baryon asymmetry of the Universe. The best such choice is identified and discussed.
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arxiv:hep-ph/0308092
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We calculate rates for hybrid meson production by electromagnetic and weak interactions in the flux-tube model. Applications include photo and electroproduction at Jefferson Laboratory and HERA, and the production of light strange and charmed hybrids in the weak decays of heavy flavours. Photoproduction of some light hybrids is predicted to be prominent in charge exchange reactions, $\gamma p \to n \cal{H}$ and accessible in $\gamma p \to p \cal{H}$. Production of light or charmed hybrids in $B$ and $D$ decays may be feasible with high statistics. Photoproduction of the axial hybrid meson is predicted to be large courtesy of $\pi$ exchange, and its strange counterpart is predicted in $B \to \psi K_H(1^+)$ with $b.r. \sim 10^{-4}$. Production rates for exotic hybrid candidates $1^{-+};(0,2)^{+-}$ are given special attention. Selection rules that can help to distinguish between hybrid and conventional states with the same $J^{PC}$ are noted.
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arxiv:hep-ph/0308098
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We calculate the photonuclear production of heavy quarks in ultraperipheral heavy ion collisions. The integrated cross section and the rapidity distribution are computed employing sound high energy QCD formalisms as the collinear and semihard approaches as well as the saturation model. In particular, the color glass condensate (CGC) formalism is also considered using a simple phenomenological parameterization for the color field correlator in the medium, which allow us to obtain more reliable estimates for charm and bottom production at LHC energies.
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arxiv:hep-ph/0308120
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We report the results of the first computation related to the study of the spectator effects in the rare decay mode $B\to K \gamma \gamma $ within the framework of Standard Model. It is found that the account of these effects results in the enhancement factor for the short-distance reducible contribution to the branching ratio.
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arxiv:hep-ph/0308126
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We calculate the high energy behavior of quark-antiquark exchange in $\gamma^* \gamma^*$ elastic scattering by summing, to all orders, the leading double logarithmic contributions of the QCD ladder diagrams. Motivation comes from the LEP data for $\sigma_{tot}^{\gamma^* \gamma^*}$ which indicate the need for secondary reggeon exchange. We show that, for large photon virtualities, this exchange is calculable in pQCD. This applies, in particular, to parts of the LEP kinematic region.
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arxiv:hep-ph/0308181
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Production of the expected high energy neutrino flux with energy greater than tens of thousands of GeV in some astrophysical sites such as the galactic plane as well as the centers of some distant galaxies is reviewed. The expected changes in these neutrino fluxes because of neutrino oscillations during their propagation to us are described. Observational signatures for these neutrino fluxes with and without neutrino oscillations are discussed.
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arxiv:hep-ph/0308188
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We summarize theoretical predictions on the decays of B_c meson.
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arxiv:hep-ph/0308214
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Non-perturbative corrections to the LO cross section formulae for DIS and the Drell-Yan process were calculated. The interaction of partons was taken into account via dressing the incoming quark lines with spectral functions. We found the effect of ground state correlation in DIS to be large in the region of small Bjorken x and low momentum transfer Q. For a quark width of the order of 200 MeV, the deviation from parton model cross section reaches as much as 50% for Q^2=10 GeV^2. On the other hand, for the values of Q well above the resonance region, the effect of ISI turned out to be small in DIS, but still substantial for the triple differential Drell-Yan cross section. Our calculations show that the shape of the high mass Drell-Yan pair transverse momentum distribution is fully determined by quark off-shellness. From comparison to the resent data on the Drell-Yan cross section from NuSea collaboration, we obtained for the quark width in the nucleon the value about 200 MeV.
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arxiv:hep-ph/0308265
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The ${q}\bar{q}$ spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons. The new $D$ states measured at different factories are studied. The $0^{++}$ light mesons are analyzed as $q\bar q$ pairs or tetraquark structures.
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arxiv:hep-ph/0308318
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We report on a next-to-leading order QCD calculation of the cross section and the spin asymmetry for isolated large-p_T prompt photon production in collisions of transversely polarized protons. Corresponding measurements may be used at RHIC to determine the transversity parton distributions of the proton.
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arxiv:hep-ph/0309035
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The uncertainties in estimating the hadronic production of the $B_c$ meson are studied under the framework of the complete $\alpha_s^4$ approach of the perturbative QCD and the gluon-gluon fusion mechanism. Quantitative comparisons on the production at TEVATRON and LHC are made. Considering the detectors at TEVATRON and LHC, we have also estimated the production with proper kinematic cuts. Based on the results, we conclude that the experimental studies of the $B_c$ meson at the two colliders will be complimentary and stimulative. We find that as c.m. energy is increasing from RUN-I to RUN-II at TEVATRON, the production cross-section increases about 20%.
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arxiv:hep-ph/0309121
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This is the user's manual of MC@NLO 2.2. This package is a practical implementation, based upon the HERWIG event generator, of the MC@NLO formalism, which allows one to incorporate NLO QCD matrix elements consistently into a parton shower framework. Processes available in this version include the hadroproduction of Higgs bosons, single vector bosons, vector boson pairs, and heavy quark-antiquark pairs. This document is self-contained, but we emphasise the main differences with respect to previous versions.
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arxiv:hep-ph/0309186
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We consider five dimensional (5D) supersymmetric SO(10) compactified on the orbifold $S^1/(Z_2\times Z_2')$ such that the SO(10) gauge symmetry is broken on both fixed points (branes), and the residual gauge symmetry is $SU(3)_c\times SU(2)_L\times U(1)_Y\times U(1)_X$. We explore one example in which the gauge symmetries on the two branes are respectively $SU(5)\times U(1)_X$ and $SU(4)_c\times SU(2)_L\times SU(2)_R$, and the MSSM gauge symmetry is recovered by the usual Higgs mechanism. We discuss how fermion masses and mixings can be understood in this framework by introducing a flavor $U(1)_F$ symmetry. Unification of the MSSM gauge couplings and proton stability are also considered. An order of magnitude increase in sensitivity could reveal proton decay.
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arxiv:hep-ph/0309205
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Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. The single spin asymmetries from the transversely polarized proton target are found to be about 20% for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS a sin(phi) asymmetry of 1% and a sin(2phi) asymmetry of about 3%.
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arxiv:hep-ph/0309209
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The relations existing between the auxiliary field (einbein field) formalism and the spinless Salpeter equation are studied in the case of two particles with the same mass, interacting via a confining potential. The problem of non-orthogonality for radial excited states in the auxiliary field formalism is discussed and found to be non-crucial. It is shown that the classical equations of motion of the rotating string model, derived from the QCD lagrangian, reduce exactly to the classical equations of motion of the phenomenological semirelativistic flux tube model, provided all auxiliary fields are eliminated correctly from the rotating string hamiltonian.
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arxiv:hep-ph/0309256
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The neutrino flux from the sun is predicted to have a CNO-cycle contribution as well as the known pp-chain component. Previously, only the fluxes from beta+ decays of 13N, 15O, and 17F have been calculated in detail. Another neutrino component that has not been widely considered is electron capture on these nuclei. We calculate the number of interactions in several solar neutrino detectors due to neutrinos from electron capture on 13N, 15O, and 17F, within the context of the Standard Solar Model. We also discuss possible non-standard models where the CNO flux is increased.
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arxiv:hep-ph/0309266
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The saturation of QCD chiral sum rules of the Weinberg-type is analyzed using ALEPH and OPAL experimental data on the difference between vector and axial-vector correlators (V-A). The sum rules exhibit poor saturation up to current energies below the tau-lepton mass. A remarkable improvement is achieved by introducing integral kernels that vanish at the upper limit of integration. The method is used to determine the value of the finite remainder of the (V-A) correlator, and its first derivative, at zero momentum: $\bar{\Pi}(0) = - 4 \bar{L}_{10} = 0.0257 \pm 0.0003 ,$ and $\bar{\Pi}^{\prime}(0) = 0.065 \pm 0.007 {GeV}^{-2}$. The dimension $d=6$ and $d=8$ vacuum condensates in the Operator Product Expansion are also determined: $<{\cal {O}}_{6}> = -(0.004 \pm 0.001) {GeV}^6,$ and $<{\cal {O}}_{8}> = -(0.001 \pm 0.006) {GeV}^8.$
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arxiv:hep-ph/0309285
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The next-to-leading order (NLO) QCD calculation for the isolated photon and isolated photon plus jet photoproduction at the ep collider DESY HERA is presented. The predictions for the isolated photon with no restrictions imposed on the jet are compared with the previous ones obtained in the small cone approximation, and the differences are found to be below 2%. The theoretical uncertainties in the cross section of the photoproduction of the photon plus jet are discussed. A short comparison with the new preliminary H1 data and with the NLO predictions of Fontannaz et al. is also presented.
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arxiv:hep-ph/0309308
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This paper has been withdrawn by the authors, since it had been the excessive repetition of the part of hep-ph/0310190.
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arxiv:hep-ph/0310034
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Firstly, I report on a recent work --carried out with T. Hambye and E. de Rafael-- on how to use the large-Nc expansion to calculate unfactorized contributions from the strong penguin operators, and their impact on observables such as epsilon'/epsilon and the Delta I = 1/2 rule. Secondly, based on work done with M. Golterman, I explain how this calculation allows one to predict some rather dramatic consequences for quenched QCD. This may help explain the present discrepancy between lattice and experimental results for epsilon'/epsilon. The emphasis of this article is put on the explanation of the method of calculation used, which is fully analytic. This allows one to build some intuition and understand the role played by the different hadronic scales in determining the size of the different contributions.
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arxiv:hep-ph/0310063
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We discuss Poincare' invariance in the context of non-relativistic effective field theories of QCD. We show, in the cases of the HQET and pNRQCD, that the algebra of the generators of the Poincare' transformations imposes precise constraints on the form of the Lagrangian. In the case of the HQET they are the relations formerly obtained by reparametrization invariance.
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arxiv:hep-ph/0310064
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Roy's equations are used to check if the scalar-isoscalar pion-pion scattering amplitudes fitted to experimental data fulfill crossing symmetry conditions. It is shown that the amplitudes describing the ``down-flat'' phase shift solution satisfy crossing symmetry below 1 GeV while the amplitudes fitted to the "up-flat'' data do not. In this way the long standing "up-down" ambiguity in the phenomenological determination of the scalar-isoscalar pion-pion amplitudes has been resolved confirming the independent result of the recent joint analysis of the pi+pi- and pi0pi0 data.
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arxiv:hep-ph/0310082
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We develop a general numerical method aimed at studying particle production from vacuum states in a variety of settings. As a first example we look at particle production in a simple cosmological model. We apply the same approach to the dynamical Casimir effect, with special focus on the case of an oscillating mirror. We confirm previous estimates and obtain long-time production rates and particle spectra for both resonant and off-resonant frequencies. Finally, we simulate a system with space and time-dependent optical properties, analogous to a one-dimensional expanding dielectric bubble. We obtain simple expressions for the dependence of the final particle number on the expansion velocity and final dielectric constant.
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arxiv:hep-ph/0310131
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