The role of strangeness in chiral and U(1)A restoration



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Gómez Nicola, Ángel and Ruiz de Elvira Carrascal, Jacobo and Vioque Rodríguez, Andrea and Álvarez Herrero, D. (2021) The role of strangeness in chiral and U(1)A restoration. European physical journal C, 81 (7). ISSN 1434-6044

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© The Author(s) 2021
We use recently derived Ward identities and lattice data for the light- and strange-quark condensates to reconstruct the scalar and pseudoscalar susceptibilities (chi S kappa, chi PK) in the isospin 1/2 channel. We show that chi S kappa develops a maximum above the QCD chiral transition, after which it degenerates with chi PK. We also obtain chi S kappa within Unitarized Chiral Perturbation Theory (UChPT) at finite temperature, when it is saturated with the K0(700) (or kappa) meson, the dominant lowest-energy state in the isospin 1/2 scalar channel of pi K scattering. Such UChPT result reproduces the expected peak structure, revealing the importance of thermal interactions, and makes it possible to examine the chi S kappa dependence on the light- and strange-quark masses. A consistent picture emerges controlled by the ml/ms ratio that allows one studying K-kappa degeneration in the chiral, two-flavor and SU(3) limits. These results provide an alternative sign for O(4)xU(1)A restoration that can be explored in lattice simulations and highlight the role of strangeness, which regulated by the strange-quark condensate helps to reconcile the current tension among lattice results regarding U(1)A restoration.

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© The Author(s) 2021
We are very grateful to Z. H. Guo for useful comments and to F. Karsch and A. Lahiri for providing detailed lattice results. Work partially supported by research contract PID2019106080GB-C21 (spanish "Ministerio de Ciencia e Innovacion"), the European Union Horizon 2020 research and innovation program under grant agreement No 824093 and the Swiss National Science Foundation, project No. PZ00P2_174228. A. V-R acknowledges support from a fellowship of the UCM predoctoral program.

Uncontrolled Keywords:Symmetry restoration; Sigma-meson; QCD; Pion; Transition; Scattering; Resonance; Phase; Roy.
Subjects:Sciences > Physics > Physics-Mathematical models
Sciences > Physics > Mathematical physics
ID Code:67997
Deposited On:11 Oct 2021 16:01
Last Modified:13 Oct 2021 07:19

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