52 research outputs found
Chiral Symmetry in Two-Color QCD at Finite Temperature
We study the chiral symmetry in two-color QCD with N massless flavors at
finite temperature, using an effective theory. For the gauge group SU(2), the
chiral symmetry is enlarged to SU(2N), which is then spontaneously broken to
Sp(2N) at zero temperature. At finite temperature, and when the axial anomaly
can be neglected, we find a first order phase transition occurring for two or
more flavors. In the presence of instantons, the symmetry restoration
unambiguously remains first order for three or more massless flavors. These
results could be relevant for lattice studies of chiral symmetry at finite
temperature and density.Comment: 10 pages, Revte
Production Ratios of Strange Baryons from QGP with Diquarks
Assuming that vector and scalar diquarks exist in the Quark-Gluon Plasma near
the critical temporature , baryons can be produced through the processes
of quarks and diquarks forming baryon states. Ratios of different
baryons can be estimated through this method, if such kind of QGP with diquarks
can exists.Comment: Correct some expressions of equation
Thermal Effects on the Low Energy N=2 SUSY Yang-Mills Theory
Using the low energy effective action of the N=2 supersymmetric SU(2)
Yang-Mills theory we calculate the free energy at finite temperature, both in
the semiclassical region and in the dual monopole/dyon theory. In all regions
the free energy depends on both the temperature T and the appropriate moduli
parameter, and is thus minimized only for specific values of the moduli
parameter, in contrast to the T=0 case where the energy vanishes all over the
moduli space. Within the validity of perturbation theory, we find that the
finite temperature Yang-Mills theory is stable only at definite points in the
moduli space, i.e. for a specific value of the monopole/dyon mass or when the
scalar field expectation value goes to infinity.Comment: 24 pages, Latex, uses axodra
Polyakov Loops versus Hadronic States
The order parameter for the pure Yang-Mills phase transition is the Polyakov
loop which encodes the symmetries of the Z_N center of the SU(N) gauge group.
On the other side the physical degrees of freedom of any asymptotically free
gauge theory are hadronic states. Using the Yang-Mills trace anomaly and the
exact Z_N symmetry we construct a model able to communicate to the hadrons the
information carried by the order parameter.Comment: RevTex4 2-col., 6 pages, 2 figures. Typos fixed and added a paragraph
in the conclusion
Two-point functions for SU(3) Polyakov Loops near T_c
We discuss the behavior of two point functions for Polyakov loops in a SU(3)
gauge theory about the critical temperature, T_c. From a Z(3) model, in mean
field theory we obtain a prediction for the ratio of masses at T_c, extracted
from correlation functions for the imaginary and real parts of the Polyakov
loop. This ratio is m_i/m_r = 3 if the potential only includes terms up to
quartic order in the Polyakov loop; its value changes as pentic and hexatic
interactions become important. The Polyakov Loop Model then predicts how
m_i/m_r changes above T_c.Comment: 5 pages, no figures; reference adde
Real Time Correlators in Hot (2+1)d QCD
We use dimensional reduction techniques to relate real time finite T
correlation functions in (2+1) dimensional QCD to bound state parameters in a
generalized 't Hooft model with an infinite number of heavy quark and adjoint
scalar fields. While static susceptibilities and correlation functions of the
DeTar type can be calculated using only the light (static) gluonic modes, the
dynamical correlators require the inclusion of the heavy modes. In particular
we demonstrate that the leading T perturbative result can be understood in
terms of the bound states of the 2d model and that consistency requires bound
state trajectories composed of both quarks and adjoint scalars. We also propose
a non-perturbative expression for the dynamical DeTar correlators at small
spatial momenta.Comment: 21 pages, Latex, uses axodra
The Superfluid and Conformal Phase Transitions of Two-Color QCD
The phase structure of two-color QCD is examined as a function of the
chemical potential and the number of light quark flavors. We consider effective
Lagrangians for two-color QCD containing the Goldstone excitations, spin-one
particles and negative intrinsic parity terms. We discuss the possibility of a
conformal phase transition and the enhancement of the global symmetries as the
number of flavors is increased. The effects of a quark chemical potential on
the spin-one particles and on the negative intrinsic parity terms are analyzed.
It is shown that the phase diagram that is predicted by the linearly realized
effective Lagrangian at tree-level matches exactly that predicted by chiral
perturbation theory.Comment: ReVTeX, 23 pages, 3 figures. Discussion of vector condensation
extended, two figures added, references adde
Covariant derivative expansion of fermionic effective action at high temperatures
We derive the fermionic contribution to the 1-loop effective action for A_4
and A_i fields at high temperatures, assuming that gluon fields are slowly
varying but allowing for an arbitrary amplitude of A_4.Comment: RevTex 4, 11 pages, 3 figures. Version 2: Typos corrected; magnetic
fields restricted to parallel sector. Version accepted for publication in PR
Covariant derivative expansion of Yang-Mills effective action at high temperatures
Integrating out fast varying quantum fluctuations about Yang--Mills fields
A_i and A_4, we arrive at the effective action for those fields at high
temperatures. Assuming that the fields A_i and A_4 are slowly varying but that
the amplitude of A_4 is arbitrary, we find a non-trivial effective gauge
invariant action both in the electric and magnetic sectors. Our results can be
used for studying correlation functions at high temperatures beyond the
dimensional reduction approximation, as well as for estimating quantum weights
of classical static configurations such as dyons.Comment: Minor changes. References added. Paper accepted for publication in
Phys.Rev.
Partial Deconfinement in Color Superconductivity
We analyze the fate of the unbroken SU(2) color gauge interactions for 2
light flavors color superconductivity at non zero temperature. Using a simple
model we compute the deconfining/confining critical temperature and show that
is smaller than the critical temperature for the onset of the superconductive
state itself. The breaking of Lorentz invariance, induced already at zero
temperature by the quark chemical potential, is shown to heavily affect the
value of the critical temperature and all of the relevant features related to
the deconfining transition. Modifying the Polyakov loop model to describe the
SU(2) immersed in the diquark medium we argue that the deconfinement transition
is second order. Having constructed part of the equation of state for the 2
color superconducting phase at low temperatures our results are relevant for
the physics of compact objects featuring a two flavor color superconductive
state.Comment: 9 pp, 4 eps-figs, version to appear in PR
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