2,546 research outputs found
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
Thermal Restoration of Chiral Symmetry in Supersymmetric Nambu-Jona-Lasinio Model with Soft SUSY Breaking
The supersymmetric version of the Nambu-Jona-Lasinio model is investigated in
connection with the chiral symmetry breaking induced by a soft SUSY breaking
term. It is found that the broken chiral symmetry due to the soft breaking term
is restored at suitably high temperature and the symmetry restoration occurs as
first-order phase transitions. The critical temperature at which the chiral
symmetry is restored is determined as a function of the strength of the soft
breaking term and the field coupling constant. The dynamical fermion mass is
calculated at finite temperature. Some possible applications to the breaking
scenario of unified field theories are discussed.Comment: 9 pages, 2 figure
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
Nambu-Jona-Lasinio Model in Curved Space-Time
The phase structure of Nambu-Jona-Lasinio model with N-component fermions in
curved space-time is studied in the leading order of the 1/N expansion.
The effective potential for composite operator is calculated
by using the normal coordinate expansion in the Schwinger proper-time method.
The existence of the first-order phase transition caused by the change of the
space-time curvature is confirmed and the dynamical mass of the fermion is
calculated as a simultaneous function of the curvature and the four-fermion
coupling constant.
The phase diagram in the curvature and the coupling constant is obtained.Comment: 8 pages, 3 figures not included, uses LaTeX, HUPD-931
Two-loop matching coefficients for the strong coupling in the MSSM
When relating the strong coupling , measured at the scale of the
boson mass, to its numerical value at some higher energy, for example the
scale of Grand Unification, it is important to include higher order corrections
both in the running of and the decoupling of the heavy particles. We
compute the two-loop matching coefficients for within the Minimal
Supersymmetric Standard Model (MSSM) which are necessary for a consistent
three-loop evolution of the strong coupling constant. Different scenarios for
the hierarchy of the supersymmetric scales are considered and the numerical
effects are discussed. We find that the three-loop effects can be as large as
and sometimes even larger than the uncertainty induced by the current
experimental accuracy of .Comment: 22 pages, 8 figures (13 ps/eps-files
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 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
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