skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ultrasoft Quark Damping in High-T QCD

Abstract

We determine the ultrasoft quark damping rates in the context of next-to-leading order hard-thermal-loop summed perturbation of high-temperature QCD. Three types of divergences are encountered: infrared, light-cone and at specific points determined by the gluon energies. The infrared divergence persists and is logarithmic whereas the two others are circumvented.

Authors:
 [1];  [2];  [3]
  1. Physics Department, United Arab Emirates University, POB 17551 Al Ain (United Arab Emirates)
  2. Facutle de Physique, USTHB, BP32 Al Alia, Bab Ezzouar 16111 Alger (Algeria)
  3. Departement de Physique, Ecole Normale Superieure, BP92 Vieux-Kouba, 16052 Alger (Algeria)
Publication Date:
OSTI Identifier:
21056901
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 892; Journal Issue: 1; Conference: QCHS7: 7. conference on quark confinement and the hadron spectrum, Ponta Delgada, Acores (Portugal), 2-7 Sep 2006; Other Information: DOI: 10.1063/1.2714460; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; GLUONS; INFRARED DIVERGENCES; LIGHT CONE; PERTURBATION THEORY; QUANTUM CHROMODYNAMICS; QUARK MATTER; QUARKS

Citation Formats

Abada, Abdessamad, Daira-Aifa, Nacera, and Bouakaz, Karima. Ultrasoft Quark Damping in High-T QCD. United States: N. p., 2007. Web. doi:10.1063/1.2714460.
Abada, Abdessamad, Daira-Aifa, Nacera, & Bouakaz, Karima. Ultrasoft Quark Damping in High-T QCD. United States. doi:10.1063/1.2714460.
Abada, Abdessamad, Daira-Aifa, Nacera, and Bouakaz, Karima. Tue . "Ultrasoft Quark Damping in High-T QCD". United States. doi:10.1063/1.2714460.
@article{osti_21056901,
title = {Ultrasoft Quark Damping in High-T QCD},
author = {Abada, Abdessamad and Daira-Aifa, Nacera and Bouakaz, Karima},
abstractNote = {We determine the ultrasoft quark damping rates in the context of next-to-leading order hard-thermal-loop summed perturbation of high-temperature QCD. Three types of divergences are encountered: infrared, light-cone and at specific points determined by the gluon energies. The infrared divergence persists and is logarithmic whereas the two others are circumvented.},
doi = {10.1063/1.2714460},
journal = {AIP Conference Proceedings},
number = 1,
volume = 892,
place = {United States},
year = {Tue Feb 27 00:00:00 EST 2007},
month = {Tue Feb 27 00:00:00 EST 2007}
}
  • The two-loop ultrasoft contributions to the next-to-leading logarithmic (NLL) running of the QCD potentials at order v{sup 2} are determined. The results represent an important step towards the next-to-next-to-leading logarithmic (NNLL) description of heavy quark pair production and annihilation close to threshold.
  • Within the framework of perturbative resummation scheme of Pisarski and Braaten, the decay or damping rate of a moving heavy quark (muon) to leading order in weak coupling in hot QCD (QED) is examined. Although, as is well known, the conventionally defined damping rate diverges logarithmically at the infrared limit, it is shown that no such divergence appears in the physically measurable decay rate. Cancellation occurs between the contribution from the thermal decay diagram and the contribution from the diagrams with thermal radiative correction.''
  • We present a complete calculation of the quark damping rate at zero momentum, to leading order in the QCD coupling constant {ital g} at a nonzero temperature {ital T}. All terms of leading order in {ital g} are included by the resummation of an infinite subset of higher-loop diagrams. At zero momentum the damping rates for the quark and the plasmino (a collective mode with opposite chirality and/or helicity) are equal: for three flavors of massless quarks, the result is {gamma}{congruent}0.151{ital g}{sup 2}{ital T}. We also examine the recent controversy over the gauge dependence of the quark damping rate, andmore » show how it is resolved when dimensional regularization is used as an infrared regulator of mass singularities.« less
  • In supersymmetric theories, the top quark can decay into its scalar partner plus a neutralino, with an appreciable rate. We calculate the {ital O}({alpha}{sub {ital s}}) QCD corrections to this decay mode in the minimal supersymmetric extension of the standard model. These corrections can be either positive or negative and increase logarithmically with the gluino mass. For gluino masses below 1 TeV, they are at most of the order of ten percent and, therefore, well under control. {copyright} {ital 1996 The American Physical Society.}
  • We calculate the fermion damping rates to second order in powers of the external momentum in the context of QED at finite temperature using the hard-thermal-loop summation scheme. We find the coefficients of zeroth and first orders finite whereas that of second order logarithmically infrared sensitive. The calculation is done in covariant gauge and the result is independent of gauge fixing.