Nonequilibrium chiral perturbation theory and disoriented chiral condensates

Abstract

We analyse the extension of Chiral Perturbation Theory to describe a meson gas out of thermal equilibrium. For that purpose, we let the pion decay constant be a time-dependent function and work within the Schwinger-Keldysh contour technique. A useful connection with curved space-time QFT allows to consistently renormalise the model, introducing two new low-energy constants in the chiral limit. We discuss the applicability of our approach within a Relativistic Heavy-Ion Collision environment. In particular, we investigate the formation of Disoriented Chiral Condensate domains in this model, via the parametric resonance mechanism.

Comments: Talk given in ``Hadron Physics: Effective Theories of Low Energy QCD'', Coimbra, Portugal, Sept. 10-15 1999. Uses aipproc.sty, available at ftp://ftp.aip.org/ems/tex/macros/proceedings/6x9