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Title: Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ 4 theory

To understand the dynamics of thermalization in heavy ion collisions in the perturbative framework it is essential to first find corrections to the free-streaming classical gluon fields of the McLerran-Venugopalan model. The corrections that lead to deviations from free streaming (and that dominate at late proper time) would provide evidence for the onset of isotropization (and, possibly, thermalization) of the produced medium. To find such corrections we calculate the late-time two-point Green function and the energy-momentum tensor due to a single 2 → 2 scattering process involving two classical fields. To make the calculation tractable we employ the scalar φ 4 theory instead of QCD. We compare our exact diagrammatic results for these quantities to those in kinetic theory and find disagreement between the two. The disagreement is in the dependence on the proper time τ and, for the case of the two-point function, is also in the dependence on the space-time rapidity η: the exact diagrammatic calculation is, in fact, consistent with the free streaming scenario. Kinetic theory predicts a build-up of longitudinal pressure, which, however, is not observed in the exact calculation. We conclude that we find no evidence for the beginning of the transition from the free-streamingmore » classical fields to the kinetic theory description of the produced matter after a single 2 → 2 rescattering.« less
Authors:
 [1] ;  [1]
  1. The Ohio State Univ., Columbus, OH (United States). Dept of Physics
Publication Date:
Grant/Contract Number:
SC0004286
Type:
Accepted Manuscript
Journal Name:
Journal of High Energy Physics (Online)
Additional Journal Information:
Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2018; Journal Issue: 3; Journal ID: ISSN 1029-8479
Publisher:
Springer Berlin
Research Org:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Perturbative QCD; Quark-Gluon Plasma
OSTI Identifier:
1506448

Kovchegov, Yuri V., and Wu, Bin. Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ4 theory. United States: N. p., Web. doi:10.1007/jhep03(2018)157.
Kovchegov, Yuri V., & Wu, Bin. Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ4 theory. United States. doi:10.1007/jhep03(2018)157.
Kovchegov, Yuri V., and Wu, Bin. 2018. "Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ4 theory". United States. doi:10.1007/jhep03(2018)157. https://www.osti.gov/servlets/purl/1506448.
@article{osti_1506448,
title = {Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ4 theory},
author = {Kovchegov, Yuri V. and Wu, Bin},
abstractNote = {To understand the dynamics of thermalization in heavy ion collisions in the perturbative framework it is essential to first find corrections to the free-streaming classical gluon fields of the McLerran-Venugopalan model. The corrections that lead to deviations from free streaming (and that dominate at late proper time) would provide evidence for the onset of isotropization (and, possibly, thermalization) of the produced medium. To find such corrections we calculate the late-time two-point Green function and the energy-momentum tensor due to a single 2 → 2 scattering process involving two classical fields. To make the calculation tractable we employ the scalar φ4 theory instead of QCD. We compare our exact diagrammatic results for these quantities to those in kinetic theory and find disagreement between the two. The disagreement is in the dependence on the proper time τ and, for the case of the two-point function, is also in the dependence on the space-time rapidity η: the exact diagrammatic calculation is, in fact, consistent with the free streaming scenario. Kinetic theory predicts a build-up of longitudinal pressure, which, however, is not observed in the exact calculation. We conclude that we find no evidence for the beginning of the transition from the free-streaming classical fields to the kinetic theory description of the produced matter after a single 2 → 2 rescattering.},
doi = {10.1007/jhep03(2018)157},
journal = {Journal of High Energy Physics (Online)},
number = 3,
volume = 2018,
place = {United States},
year = {2018},
month = {3}
}