Dynamical fermion masses under the influence of Kaluza-Klein fermions in extra dimensions

The dynamical fermion mass generation in the 4-dimensional brane is discussed in a model with 5-dimensional Kaluza-Klein fermions in interaction with 4-dimensional fermions. It is found that the dynamical fermion masses are generated beyond the critical radius of the compactified extra dimensional space and may be made small compared with masses of the Kaluza-Klein modes.Comment: 11 pages, 3 figures, REVTeX; typos corrected, comment about the symmetry breaking added in section 4, new references for section 1 adde

Dynamical Fermion Masses Under the Influence of Kaluza-Klein Fermions in Randall-Sundrum Background

The dynamical fermion mass generation on the D3-brane in the Randall-Sundrum space-time is discussed in a model with bulk fermions in interaction with fermions on the branes. It is found that the dynamical fermion masses are generated at the natural (R.-S.) radius of the compactified extra space and may be made small compared with masses of the Kaluza-Klein modes which is of order of TeV.Comment: 10 pages, 4 figures, REVTeX; footnote added in section 4, new references adde

Structure of Chiral Phase Transitions at Finite Temperature in Abelian Gauge Theories

The mechanism of the chiral symmetry breaking is investigated in the strong-coupling Abelian gauge theories at finite temperature. The Schwinger-Dyson equation in Landau gauge is employed in the real time formalism and is solved numerically within the framework of the instantaneous exchange approximation including the effect of the hard thermal loop for the photon propagator. It is found that the chiral symmetry is broken below the critical temperature T for sufficiently large coupling. The chiral phase transition is found to be of the 2nd order and the phase diagram on the $T-\alpha$ plane is obtained. It is investigated how the structure of the chiral phase transition is affected by the hard thermal loops in the photon propagator.Comment: 15pages, uses epic.sty and eepic.st

η′−g∗−g\eta'-g^*-g Transition Form Factor with Gluon Content Contribution Tested

We study the $\eta'-g^*-g$ transition form factor by using the $\eta'$ wave function constrained by the experimental data on the $\eta'-\gamma^*-\gamma$ transition form factor provided by CLEO and L3 . We also take into account the contribution of the possible gluonic content of the $\eta'$ meson.Comment: RevTex 10 pages, 4 figures, the version accepted for publication in Phys. Rev.

QCD anomaly coupling for the η′-g*-g vertex in inclusive decay B→ η′Xs

The QCD anomaly coupling of η′-g-g is treated as the axial vector current triangle anomaly. By assuming the divergent axial vector coupling of the η′ meson with the quark line in the triangle diagram, we calculate the QCD anomaly of η′-g-g as well as the QED anomaly of η′-γ-γ with only one common parameter Kη′. We obtain consistent results of the branching ratios for ..

Covariant boost and structure functions of baryons in Gross-Neveu models

Baryons in the large N limit of two-dimensional Gross-Neveu models are reconsidered. The time-dependent Dirac-Hartree-Fock approach is used to boost a baryon to any inertial frame and shown to yield the covariant energy-momentum relation. Momentum distributions are computed exactly in arbitrary frames and used to interpolate between the rest frame and the infinite momentum frame, where they are related to structure functions. Effects from the Dirac sea depend sensitively on the occupation fraction of the valence level and the bare fermion mass and do not vanish at infinite momentum. In the case of the kink baryon, they even lead to divergent quark and antiquark structure functions at x=0.Comment: 13 pages, 12 figures; v2: minor correction

Phase structure of four-fermion theories at finite temperature and chemical potential in arbitrary dimensions

The phase structure of four-fermion theories is thoroughly investigated with varying temperature and chemical potential for arbitrary space-time dimensions (2 ≤ D < 4) by using the 1/N expansion method. It is shown that the chiral symmetry is restored in the theory under consideration for sufficiently high temperature and/or chemical potential. The critical line dividing the symmetric and broken phase is given explicitly. It is found that for space-time dimension 2 ≤ D < 3 both the first-order and second-order phase transition occur depending on the value of temperature and chemical potential while for 3 ≤ D < 4 only the second-order phase transition exists

Finite grand unified theories and inflation

A class of finite GUTs in curved spacetime is considered in connection with the cosmological inflation scenario. It is confirmed that the use of the running scalar-gravitational coupling constant in these models helps realizing a successful chaotic inflation. The analyses are made for some different sets of the models