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

• Published in: The European physical journal. C, Particles and fields Vol. 81; no. 7; p. 637
• Main Authors: Gómez Nicola, A., Ruiz de Elvira, J., Vioque-Rodríguez, A., Álvarez-Herrero, D.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2021; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Cosmology; Chiral dynamics; Condensates; Degeneration; Elementary Particles; Flavor (particle physics); Hadrons; Heavy Ions; Light; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Perturbation theory; Phase transitions; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quarks; Regular Article - Theoretical Physics; Restoration; Simulation; Strangeness; String Theory; Symmetry; Theoretical physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-021-09458-1

We use recently derived Ward identities and lattice data for the light- and strange-quark condensates to reconstruct the scalar and pseudoscalar susceptibilities ( χ S κ , χ P K ) in the isospin 1/2 channel. We show that χ S κ develops a maximum above the QCD chiral transition, after which it degenerates with χ P K . We also obtain χ S κ within Unitarized Chiral Perturbation Theory (UChPT) at finite temperature, when it is saturated with the K 0 ∗ ( 700 ) (or κ ) meson, the dominant lowest-energy state in the isospin 1/2 scalar channel of π K scattering. Such UChPT result reproduces the expected peak structure, revealing the importance of thermal interactions, and makes it possible to examine the χ S κ dependence on the light- and strange-quark masses. A consistent picture emerges controlled by the m l / m s ratio that allows one studying K - κ degeneration in the chiral, two-flavor and SU (3) limits. These results provide an alternative sign for O ( 4 ) × U ( 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.