RT Journal Article
T1 Chemical nonequilibrium for interacting bosons: applications to the pion gas
A1 Fernández Fraile, Daniel
A1 Gómez Nicola, Ángel
AB We consider an interacting pion gas in a stage of the system evolution where thermal but not chemical equilibrium has been reached, i.e., for temperatures between thermal and chemical freeze-out T(ther) < T < T(chem) reached in relativistic heavy-ion collisions. Approximate particle number conservation is implemented by a nonvanishing pion number chemical potential mu(pi) within a diagrammatic thermal field-theory approach, valid in principle for any bosonic field theory in this regime. The resulting Feynman rules are derived here and applied within the context of chiral perturbation theory to discuss thermodynamical quantities of interest for the pion gas such as the free energy, the quark condensate, and thermal self-energy. In particular, we derive the mu(pi) not equal 0 generalization of Luscher and Gell-Mann-Oakes-Renner-type relations. We pay special attention to the comparison with the conventional kinetic theory approach in the dilute regime, which allows for a check of consistency of our approach. Several phenomenological applications are discussed, concerning chiral symmetry restoration, freeze-out conditions, and Bose-Einstein pion condensation.
PB Amer Physical Soc
SN 1550-7998
YR 2009
FD 2009-09
LK https://hdl.handle.net/20.500.14352/44575
UL https://hdl.handle.net/20.500.14352/44575
LA eng
NO © 2009 The American Physical Society.We acknowledge financial support from the Spanish research Projects No. FPA2007-29115-E, No. PR34- 1856-BSCH, No. CCG07-UCM/ESP-2628, No. FPA2008- 00592, No. FIS2008-01323, and from the FPI programme (No. BES-2005-6726).
NO Spanish research Projects
NO FPI programme
NO BSCH
DS Docta Complutense
RD 18 abr 2025