Anomalous pseudoscalar-photon vertex in and out of equilibrium
- Department of Physics, University of Washington, Seattle, Washington 98195 (United States)
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)
- Department of Physics, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
The anomalous pseudoscalar-photon vertex is studied in real time in and out of equilibrium in a constituent quark model. The goal is to understand the in-medium modifications of this vertex, exploring the possibility of enhanced isospin breaking by electromagnetic effects as well as the formation of neutral pion condensates in a rapid chiral phase transition in peripheral, ultrarelativistic heavy-ion collisions. In equilibrium the effective vertex is afflicted by infrared and pinch singularities that require hard thermal loop and width corrections of the quark propagator. The resumed effective equilibrium vertex vanishes near the chiral transition in the chiral limit. In a strongly out of equilibrium chiral phase transition we find that the chiral condensate drastically modifies the quark propagators and the effective vertex. The ensuing dynamics for the neutral pion results in a potential enhancement of isospin breaking and the formation of {pi}{sup 0} condensates. While the anomaly equation and the axial Ward identity are not modified by the medium in or out of equilibrium, the effective real-time pseudoscalar-photon vertex is sensitive to low energy physics. (c) 2000 The American Physical Society.
- OSTI ID:
- 20215939
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 61, Issue 6; Other Information: PBD: 15 Mar 2000; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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