Vanishing Polyakov loop for QCD with twelve massless quarks

We consider continuum-formulation QCD in four dimensions with twelve massless fundamental quark flavors. Splitting the SU(N) gauge field into background and fluctuation parts, we use well-developed techniques to calculate the one-loop effective action for the theory. We find that for constant self-d...

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Main Authors: Seth Grable, Paul Romatschke
Format: Article
Language:English
Published: Elsevier 2025-03-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S037026932500070X
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author Seth Grable
Paul Romatschke
author_facet Seth Grable
Paul Romatschke
author_sort Seth Grable
collection DOAJ
description We consider continuum-formulation QCD in four dimensions with twelve massless fundamental quark flavors. Splitting the SU(N) gauge field into background and fluctuation parts, we use well-developed techniques to calculate the one-loop effective action for the theory. We find that for constant self-dual background field-strength tensor the notorious infrared divergences of the effective action cancel between gauge and matter sectors if the number of massless quark flavors is exactly Nf=4N. The ultraviolet divergencies of the effective action are non-perturbatively renormalized with a β-function that matches the known perturbative result in the high energy limit. The resulting UV- and IR-finite effective action possesses a non-trivial saddle which has lower free energy than the perturbative vacuum, and for which the expectation value of the Polyakov loop vanishes. Inclusion of finite temperature effects points to the presence of a first-order phase transition to the perturbative vacuum with a calculable critical temperature.
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spelling doaj-art-d952e2a9c8fe4dbfa560cfac1cb25db22025-08-20T02:59:53ZengElsevierPhysics Letters B0370-26932025-03-0186213931010.1016/j.physletb.2025.139310Vanishing Polyakov loop for QCD with twelve massless quarksSeth Grable0Paul Romatschke1Department of Physics, University of Colorado, Boulder, CO 80309, USADepartment of Physics, University of Colorado, Boulder, CO 80309, USA; Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USAWe consider continuum-formulation QCD in four dimensions with twelve massless fundamental quark flavors. Splitting the SU(N) gauge field into background and fluctuation parts, we use well-developed techniques to calculate the one-loop effective action for the theory. We find that for constant self-dual background field-strength tensor the notorious infrared divergences of the effective action cancel between gauge and matter sectors if the number of massless quark flavors is exactly Nf=4N. The ultraviolet divergencies of the effective action are non-perturbatively renormalized with a β-function that matches the known perturbative result in the high energy limit. The resulting UV- and IR-finite effective action possesses a non-trivial saddle which has lower free energy than the perturbative vacuum, and for which the expectation value of the Polyakov loop vanishes. Inclusion of finite temperature effects points to the presence of a first-order phase transition to the perturbative vacuum with a calculable critical temperature.http://www.sciencedirect.com/science/article/pii/S037026932500070X
spellingShingle Seth Grable
Paul Romatschke
Vanishing Polyakov loop for QCD with twelve massless quarks
Physics Letters B
title Vanishing Polyakov loop for QCD with twelve massless quarks
title_full Vanishing Polyakov loop for QCD with twelve massless quarks
title_fullStr Vanishing Polyakov loop for QCD with twelve massless quarks
title_full_unstemmed Vanishing Polyakov loop for QCD with twelve massless quarks
title_short Vanishing Polyakov loop for QCD with twelve massless quarks
title_sort vanishing polyakov loop for qcd with twelve massless quarks
url http://www.sciencedirect.com/science/article/pii/S037026932500070X
work_keys_str_mv AT sethgrable vanishingpolyakovloopforqcdwithtwelvemasslessquarks
AT paulromatschke vanishingpolyakovloopforqcdwithtwelvemasslessquarks