Topological susceptibility in finite temperature (2+1)-flavor QCD using gradient flow

(WHOT-QCD Collaboration)

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

We compute the topological charge and its susceptibility in finite temperature (2+1)-flavor QCD on the lattice applying a gradient flow method. With the Iwasaki gauge action and nonperturbatively O(a)-improved Wilson quarks, we perform simulations on a fine lattice with a≃0.07 fm at a heavy u, d quark mass with mπ/mρ≃0.63, but approximately physical s quark mass with mηss/mφ≃0.74. In a temperature range from T≃174 MeV (Nt=16) to 697 MeV (Nt=4), we study two topics on the topological susceptibility. One is a comparison of gluonic and fermionic definitions of the topological susceptibility. Because the two definitions are related by chiral Ward-Takahashi identities, their equivalence is not trivial for lattice quarks which violate the chiral symmetry explicitly at finite lattice spacings. The gradient flow method enables us to compute them without being bothered by the chiral violation. We find a good agreement between the two definitions with Wilson quarks. The other is a comparison with a prediction of the dilute instanton gas approximation, which is relevant in a study of axions as a candidate of the dark matter in the evolution of the Universe. We find that the topological susceptibility shows a decrease in T which is consistent with the predicted χt(T)(T/Tpc)-8 for three-flavor QCD even at low temperature Tpc<T 1.5Tpc.

Original languageEnglish
Article number054502
JournalPhysical Review D
Volume95
Issue number5
DOIs
Publication statusPublished - Mar 2017

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quantum chromodynamics
quarks
magnetic permeability
gradients
temperature
instantons
equivalence
dark matter
universe
spacing
symmetry
predictions
approximation
gases
simulation

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

Cite this

Topological susceptibility in finite temperature (2+1)-flavor QCD using gradient flow. / (WHOT-QCD Collaboration).

In: Physical Review D, Vol. 95, No. 5, 054502, 03.2017.

Research output: Contribution to journalArticle

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