437 research outputs found
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
Pattern of Chiral Symmetry Restoration at Finite Temperature in A Supersymmetric Composite Model
The structure of chiral symmetry restorations at finite temperature is
thoroughly investigated in the supersymmetric Nambu-Jona-Lasinio model with a
soft supersymmetry breaking term. It is found that the broken chiral symmetry
at vanishing temperature is restored at sufficiently high temperature in two
patterns, i. e., the first order and second order phase transition depending on
the choice of the coupling constant and the supersymmetry breaking
parameter . The critical curves expressing the phase boundaries in the
plane are completely determined and the dynamically generated
fermion mass is calculated as a function of temperature.Comment: 12 pages, 4 figures, REVTe
Path-Integral Formulation of Casimir Effects in Supersymmetric Quantum Electrodynamics
The Casimir effect is an interesting phenomenon in the sense that it provides
us with one of the primitive means of extracting the energy out of the vacuum.
Since the original work of Casimir a number of works have appeared in extending
the result to the case of more general topological and dynamical configurations
of the boundary condition and to the circumstances at finite temperature and
gravity. In the studies of the Casimir effects it is common to assume the free
electromagnetic field in the bounded region. It may be interesting to extend
our arguments for fields other than the electromagnetic field. The Casimir
effect due to the free fermionic fields has been investigated by several
authors and has been found to result in an attractive force under the suitable
physical boundary conditions.Comment: 12 pages, 6 figures, REVTe
Exact Scale Invariance of Composite-Field Coupling Constants
We show that the coupling constant of a quantum-induced composite field is
scale invariant due to its compositeness condition. It is first demonstrated in
next-to-leading order in 1/N in typical models, and then we argue that it holds
exactly.Comment: 4 page
Generalized forward scattering amplitudes in QCD at high temperature
We extend to a general class of covariant gauges an approach which relates
the thermal Green functions to forward scattering amplitudes of thermal
particles. A brief discussion of the non-transversality of the thermal gluon
polarization tensor is given in this context. This method is then applied to
the calculation of the ln(T) contributions associated with general
configurations of 2 and 3-point gluon functions. The results are Lorentz
covariant and have the same structure as the ultraviolet divergent
contributions which occur at zero temperature.Comment: 10 pages, 3 figure
Analysis of Running Coupling Constant Unification in String Theory
We use recently obtained 2-loop string coupling constants to analyze a class
of string models based on orbifold compactification. Assuming weak coupling at
the string scale and single-scale unification leads to restrictions on the
spectrum of massive (between the string scale and the weak scale) matter
supermultiplets and/or on the Kac-Moody algebra level.Comment: 12 page
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