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Title: QCD running coupling with diquarks

Abstract

The running coupling constant is evaluated at order g2 within an extended model of Quantum Chromodynamics with color antitriplet scalar diquarks. Asymptotic freedom is valid also when the matter fields are originated by diquarks composed by strongly correlated pair of quarks. Diquarks slightly enhances {alpha}QCD at scales about 1 GeV, in qualitative agreement with data.

Authors:
; ;  [1]
  1. Departamento de Fisica, Instituto Tecnologico de Aeronautica, Centro Tecnico Aeroespacial, 12228-900, Sao Jose dos Campos (Brazil)
Publication Date:
OSTI Identifier:
21054844
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 884; Journal Issue: 1; Conference: 6. Latin American symposium on nuclear physics and applications, Iguazu (Argentina), 3-7 Oct 2005; Other Information: DOI: 10.1063/1.2710608; (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; ASYMPTOTIC SOLUTIONS; COLOR MODEL; COUPLING; COUPLING CONSTANTS; GEV RANGE; QUANTUM CHROMODYNAMICS; QUARK-QUARK INTERACTIONS; QUARKS

Citation Formats

Marinho, J. A. O., Gambin, E., and Frederico, T.. QCD running coupling with diquarks. United States: N. p., 2007. Web. doi:10.1063/1.2710608.
Marinho, J. A. O., Gambin, E., & Frederico, T.. QCD running coupling with diquarks. United States. doi:10.1063/1.2710608.
Marinho, J. A. O., Gambin, E., and Frederico, T.. Mon . "QCD running coupling with diquarks". United States. doi:10.1063/1.2710608.
@article{osti_21054844,
title = {QCD running coupling with diquarks},
author = {Marinho, J. A. O. and Gambin, E. and Frederico, T.},
abstractNote = {The running coupling constant is evaluated at order g2 within an extended model of Quantum Chromodynamics with color antitriplet scalar diquarks. Asymptotic freedom is valid also when the matter fields are originated by diquarks composed by strongly correlated pair of quarks. Diquarks slightly enhances {alpha}QCD at scales about 1 GeV, in qualitative agreement with data.},
doi = {10.1063/1.2710608},
journal = {AIP Conference Proceedings},
number = 1,
volume = 884,
place = {United States},
year = {Mon Feb 12 00:00:00 EST 2007},
month = {Mon Feb 12 00:00:00 EST 2007}
}
  • We discuss the new model expression {bar {alpha}}{sub an}( Q{sup 2}) recently obtained for the QCD running coupling with a regular ghost-free behavior in the {open_quotes}low Q{sup 2} {close_quotes} region. Being deduced from the standard {open_quotes}asymptotic-freedom{close_quotes} expression by imposing the Q{sup 2} analyticity{emdash}without any adjustable parameters{emdash}it has nice features: (i)The universal limiting value {bar {alpha}}{sub an}( 0)=4{pi}/{beta}{sub 0} expressed only via group symmetry factors and independent of experimental estimates on the running coupling {bar {alpha}}{sub s}(Q{sup 2}) (of QCD scale parameter {Lambda} ). This value is stable with respect to higher order corrections. (ii)Stability of IR behavior with respect tomore » higher-loop effects. (iii)Coherence between the experimental {bar {alpha}}{sub an}( M{sup 2}{sub {tau}}) value and integral information on IR {bar {alpha}}{sub s}(Q{sup 2}) behavior as extracted from jet physics data. {copyright} {ital 1997} {ital The American Physical Society}« less
  • The quark-propagator Dyson-Schwinger equation, with a running coupling constant to provide an ultraviolet regulator, with no infrared cutoff, is calculated numerically in the Landau gauge. It is shown that, for one or more generations of quarks, the chiral symmetry of the bare QCD Lagrangian is dynamically broken, so that quark masses are engendered.
  • We obtain an expression for the color-hyperfine interaction in heavy quarkonium in perturbative QCD including terms up to one loop, but going beyond one loop by letting the strong-interaction coupling constant {alpha}{sub {ital s}} run. The resulting expression cannot be written analytically in position space, but we make approximations which enable us to obtain approximate upper and lower bounds on the {ital P}-wave color-hyperfine splittings in charmonium and bottomonium.
  • We analyze heavy quark free energies in 2-flavor QCD at finite temperature and the corresponding heavy quark potential at zero temperature. Static quark-antiquark sources in color singlet, octet and color averaged channels are used to probe thermal modifications of the medium. The temperature dependence of the running coupling, {alpha}{sub qq}(r,T), is analyzed at short and large distances and is compared to zero temperature as well as quenched calculations. In part, we also compare our results to recent findings in 3-flavor QCD. We find that the characteristic length scale below which the running coupling shows almost no temperature dependence is almostmore » twice as large as the Debye screening radius. Our analysis supports recent findings which suggest that {chi}{sub c} and {psi}{sup '} are suppressed already at the (pseudo) critical temperature and thus give a probe for quark gluon plasma production in heavy ion collision experiments, while J/{psi} may survive the transition and will dissolve at higher temperatures.« less