676 research outputs found
Two-flavor condensates in chiral dynamics: temperature and isospin density effects
Isospin density and thermal corrections for several condensates are
discussed, at the one-loop level, in the frame of chiral dynamics with pionic
degrees of freedom. The evolution of such objects give an additional insight
into the condensed-pion phase transition, that occurs basically when
|\mui|>m_\pi, being |\mui| the isospin chemical potential. Calculations are
done in both phases, showing a good agreement with lattice results for such
condensates.Comment: 9 pages, 10 figure
Weinberg power counting and the quark determinant at small chemical potential
We construct an effective action for QCD by expanding the quark determinant
in powers of the chemical potential at finite temperature in the case of
massless quarks. To cut the infinite series we adopt the Weinberg power
counting criteria. We compute the minimal effective action (~p^4), expanding in
the external momentum, which implies the use of the hard thermal loop
approximation. Our main result is a gauge invariant expression for the phase
theta of the functional determinant in QCD, and recovers dimensional reduction
in the high-temperature limit. We compute, analytically, in the range
of p << 2 pi T, including perturbative and nonperturbative contributions, the
latter treated within the mean field approximation. Implications for lattice
simulations are briefly discussed.Comment: 5 pages, 2 figures. v2: title changed, expanded discussion and added
example (calculation of at high temperature). Published in PR
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