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Enhancement of photon production from nonequilibrium disoriented chiral condensates

D Boyanovsky, H. de Vega, R Holman, Prem Kumar Orcid Logo

Physical Review D, Volume: 56, Issue: 8, Pages: 5233 - 5250

Swansea University Author: Prem Kumar Orcid Logo

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DOI (Published version): 10.1103/PhysRevD.56.5233

Abstract

We study photoproduction during the non-equilibrium stages of the forma- tion of chiral condensates within the “quench” scenario of the chiral phase transition. The dynamics is modeled with a gauged linear sigma model. A novel quantum kinetic approach to the description of photoproduction far off eq...

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Published in: Physical Review D
Published: 1997
URI: https://cronfa.swan.ac.uk/Record/cronfa16108
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spelling 2020-07-16T14:44:15.7216240 v2 16108 2013-09-20 Enhancement of photon production from nonequilibrium disoriented chiral condensates 087fd097167d724ce1b13cb285741ef5 0000-0003-0867-4213 Prem Kumar Prem Kumar true false 2013-09-20 SPH We study photoproduction during the non-equilibrium stages of the forma- tion of chiral condensates within the “quench” scenario of the chiral phase transition. The dynamics is modeled with a gauged linear sigma model. A novel quantum kinetic approach to the description of photoproduction far off equilibrium is developed. We find that non-equilibrium spinodal instabilities of long wavelength pion fluctuations are responsible for an enhanced photo- production rate for energies ≤ 80 MeV at order α. These non-equilibrium effects lead to a larger contribution than the typical processes in the medium, including that of the anomalous neutral pion decay π0 → 2γ (which is of order α2). We follow the evolution of the dynamics throughout the phase transition, which in this scenario occurs on a time scale of about 2.5−3 fm/c and integrate the photon yield through its evolution. The spectrum of photons produced throughout the phase transition is a non- equilibrium one. For thermal initial conditions at the time of the quench it interpolates between a thermal distri- bution about 6% above the initial temperature (at the time of the quench) for low energy ≤ 80 MeV photons, and a high energy tail in thermal equilibrium at the initial temperature, with a smooth crossover at 100 MeV. The rate displays a peak at ∼ 35 MeV which receives a larger enhancement the closer the initial temperature at the time of the quench is to the critical tempera- ture. It is found that the enhancement of photoproduction at low energies is not an artifact caused by the initial distribution of the photons, but is due to the pionic instabilities. We suggest that these strong out of equilibrium effects may provide experimental signatures for the formation and relaxation of DCC's in heavy ion collisions. Journal Article Physical Review D 56 8 5233 5250 31 12 1997 1997-12-31 10.1103/PhysRevD.56.5233 COLLEGE NANME Physics COLLEGE CODE SPH Swansea University 2020-07-16T14:44:15.7216240 2013-09-20T10:43:46.4825011 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics D Boyanovsky 1 H. de Vega 2 R Holman 3 Prem Kumar 0000-0003-0867-4213 4
title Enhancement of photon production from nonequilibrium disoriented chiral condensates
spellingShingle Enhancement of photon production from nonequilibrium disoriented chiral condensates
Prem Kumar
title_short Enhancement of photon production from nonequilibrium disoriented chiral condensates
title_full Enhancement of photon production from nonequilibrium disoriented chiral condensates
title_fullStr Enhancement of photon production from nonequilibrium disoriented chiral condensates
title_full_unstemmed Enhancement of photon production from nonequilibrium disoriented chiral condensates
title_sort Enhancement of photon production from nonequilibrium disoriented chiral condensates
author_id_str_mv 087fd097167d724ce1b13cb285741ef5
author_id_fullname_str_mv 087fd097167d724ce1b13cb285741ef5_***_Prem Kumar
author Prem Kumar
author2 D Boyanovsky
H. de Vega
R Holman
Prem Kumar
format Journal article
container_title Physical Review D
container_volume 56
container_issue 8
container_start_page 5233
publishDate 1997
institution Swansea University
doi_str_mv 10.1103/PhysRevD.56.5233
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 0
active_str 0
description We study photoproduction during the non-equilibrium stages of the forma- tion of chiral condensates within the “quench” scenario of the chiral phase transition. The dynamics is modeled with a gauged linear sigma model. A novel quantum kinetic approach to the description of photoproduction far off equilibrium is developed. We find that non-equilibrium spinodal instabilities of long wavelength pion fluctuations are responsible for an enhanced photo- production rate for energies ≤ 80 MeV at order α. These non-equilibrium effects lead to a larger contribution than the typical processes in the medium, including that of the anomalous neutral pion decay π0 → 2γ (which is of order α2). We follow the evolution of the dynamics throughout the phase transition, which in this scenario occurs on a time scale of about 2.5−3 fm/c and integrate the photon yield through its evolution. The spectrum of photons produced throughout the phase transition is a non- equilibrium one. For thermal initial conditions at the time of the quench it interpolates between a thermal distri- bution about 6% above the initial temperature (at the time of the quench) for low energy ≤ 80 MeV photons, and a high energy tail in thermal equilibrium at the initial temperature, with a smooth crossover at 100 MeV. The rate displays a peak at ∼ 35 MeV which receives a larger enhancement the closer the initial temperature at the time of the quench is to the critical tempera- ture. It is found that the enhancement of photoproduction at low energies is not an artifact caused by the initial distribution of the photons, but is due to the pionic instabilities. We suggest that these strong out of equilibrium effects may provide experimental signatures for the formation and relaxation of DCC's in heavy ion collisions.
published_date 1997-12-31T03:18:24Z
_version_ 1763750449417027584
score 11.037056

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