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Title: Scale-setting, flavor dependence, and chiral symmetry restoration

Abstract

Here, we determine the flavor dependence of the renormalization-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD’s gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed–gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: n cr f ≈ 9; and hence in whose neighborhood QCD is plausibly a conformal theory.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
OSTI Identifier:
1369032
Grant/Contract Number:
AC02-06CH11357; FPA2014-53631-C-2-P
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 95; Journal Issue: 11; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Dyson-Schwinger equations; dynamical chiral symmetry breaking; gluon-quark vertex; non-Abelian gauge-sector dynamics; numerical simulations of lattice-regularised QCD

Citation Formats

Binosi, D, Roberts, Craig D., and Rodriguez-Quintero, J. Scale-setting, flavor dependence, and chiral symmetry restoration. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.95.114009.
Binosi, D, Roberts, Craig D., & Rodriguez-Quintero, J. Scale-setting, flavor dependence, and chiral symmetry restoration. United States. doi:10.1103/PhysRevD.95.114009.
Binosi, D, Roberts, Craig D., and Rodriguez-Quintero, J. 2017. "Scale-setting, flavor dependence, and chiral symmetry restoration". United States. doi:10.1103/PhysRevD.95.114009.
@article{osti_1369032,
title = {Scale-setting, flavor dependence, and chiral symmetry restoration},
author = {Binosi, D and Roberts, Craig D. and Rodriguez-Quintero, J.},
abstractNote = {Here, we determine the flavor dependence of the renormalization-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD’s gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed–gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: ncrf ≈ 9; and hence in whose neighborhood QCD is plausibly a conformal theory.},
doi = {10.1103/PhysRevD.95.114009},
journal = {Physical Review D},
number = 11,
volume = 95,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 13, 2018
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  • Cited by 2
  • We combine measurements of the chiral-symmetry--restoration transition temperature and hadron masses in lattice QCD with two flavors of light quarks to estimate the transition temperature in megaelectronvolts. We compare this estimate to results of ''quenched'' QCD to estimate the effects of our large lattice spacing on the results. We find that the dynamical quarks lower the temperature of the phase transition relative to the pure gauge theory.
  • We study the leading discretization errors for staggered fermions by first constructing the continuum effective Lagrangian, including terms of O(a{sup 2}), and then constructing the corresponding effective chiral Lagrangian. The terms of O(a{sup 2}) in the continuum effective Lagrangian completely break the SU(4) flavor symmetry down to the discrete subgroup respected by the lattice theory. We find, however, that the O(a{sup 2}) terms in the potential of the chiral Lagrangian maintain an SO(4) subgroup of SU(4). It follows that the leading discretization errors in the pion masses are SO(4) symmetric, implying three degeneracies within the seven lattice irreducible representations. Thesemore » predictions hold also for perturbatively improved versions of the action. These degeneracies are observed, to a surprising degree of accuracy, in existing data. We argue that the SO(4) symmetry does not extend to the masses and interactions of other hadrons (vector mesons, baryons, etc.) or to higher order in a{sup 2}. We show how it is possible that, for physical quark masses of O(a{sup 2}), the new SO(4) symmetry can be spontaneously broken, leading to a staggered analogue of the Aoki phase of Wilson fermions. This does not, however, appear to happen for presently studied versions of the staggered action. (c) 1999 The American Physical Society.« less
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