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HK: Physik der Hadronen und Kerne
HK 13: Poster-Sitzung: Theorie
HK 13.9: Poster
Dienstag, 18. März 2003, 13:30–15:30, Foyer
Thermodynamics of the chiral condensate — •Thomas M. Schwarz1, Norbert Kaiser1, and Wolfram Weise1,2 — 1Physik-Department, Technische Universität München. — 2ECT∗, Villa Tambosi, Strada delle Tabarelle 286, I-38050 Villazzano (Trento), Italy
We study the temperature and density dependence of the scalar quark
condensate
⟨qq⟩ using effective field theory methods. Nucleons
interact via perturbative chiral pion exchange and scalar plus vector
four-point interactions. The latter are treated in relativistic mean field
approximation giving rise to an effective nucleon mass M∗ and an
effective chemical potential µ∗. Contributions from pion
fluctuations
at two-loop level are included in the self consistency equations for
M∗
and µ∗.
The strengths of the contact interactions are adjusted to the empirical
nuclear matter saturation point and compressibility κ. From this we
predict an effective nucleon mass of M∗(ρ0)≃ 0.8M. At a
temperature T≃ 17 MeV a liquid-gas phase transition is observed.
In a further step we include three-loop contributions from
2π-exchange at T=0. The dependence of the equation of
state P(T,µ,mπ) on the pion mass allows to calculate deviations
from
the leading linear decrease in density of the quark condensate. We find
that
these are small below normal nuclear matter density.
Supported in part by BMBF and GSI.