1993/09/10 by Ngee-Pong Chang, Chang, Ngee-Pong
Chemistry · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Molecular spectroscopy and chirality #Quantum chaos and dynamical systems #Quantum, superfluid, helium dynamics #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9309253
(Contributed talk at the 3rd Thermal Fields Workshop held Aug 16 - 27, 1993 at Banff, Canada. ) 6 pages, LaTeX, CCNY-HEP-93-15
arxiv created 1993/09/10 · openalex publication_date 1993/09/10 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The QCD effective action at high T shows a manifest global chiral symmetry. And calculations show that the order parameter \psibarpsi vanishes above Tc. It has been popular to refer to this Tc as chiral symmetry restoration temperature because it fits into our prejudice that chiral symmetry is like an `ordered' state, and at high T it must become disordered. In fact, NJL ground state is not an ordered spin state. The recent scenario of a generic class of disoriented chiral condensate offers an example where \psibarpsi in each little domain is nonzero, but the average over all space of \psibarpsi vanishes. Such a dcc ground state continues to break chiral invariance. But how do you reconcile this with the apparent chiral symmetry at high T? The Braaten-Pisarski action is a good laboratory to investigate the subtleties of high temperature chiral symmetry. By carrying out a canonical quantization of this highly nonlocal action, I demonstrate how the thermal vacuum at high T conserves the new β-chirality but breaks the old T=0 chirality. Lattice calculations show that the pion develops a screening mass at high T. Our continuum field theory calculations show that the QCD pion remains massless for all T. I conclude the talk by showing how the hot pion manages to accomodate the two results by propagating in the early universe with a halo.