Chiral Morphing

Abstract

Chiral symmetry undergoes a metamorphosis at $T_c$. For $T<T_c$, the usual Noether charge, $\Qa$, is dynamically broken by the vacuum. Above $T_c$, chiral symmetry undergoes a subtle change, and the Noether charge \underline{\em morphs} into $\Qbeta$, with the thermal vacuum now becoming invariant under $\Qbeta$. This vacuum is however not invariant under the old $\Qa$ transformations. As a result, the pion remains strictly massless at high $T$. The pion propagates in the early universe with a halo. New order parameters are proposed to probe the structure of the new thermal vacuum.

14 pages, LaTeX, CCNY-HEP-94-6 Invited contribution to the Marshak Memorial volume, edited by E.C.G. Sudarshan, to be published by World Scientific Publishing Co., Singapore, 1994. **** Earlier version had email bug due to transmission problem