Enhancement of axial anomaly effects in hot two-color QCD: FRG approach in the linear sigma model

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Main Authors: Fejős, Gergely, Suenaga, Daiki
Format: Preprint
Published: 2025
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author Fejős, Gergely
Suenaga, Daiki
author_facet Fejős, Gergely
Suenaga, Daiki
contents We investigate the thermal properties of hadrons in two-color quantum chromodynamics (QC$_2$D) using the functional renormalization group (FRG) method, with particular focus on modifications of the $U(1)$ axial anomaly effects. The hadrons are described by a linear sigma model (LSM) based on the Pauli-Gürsey $SU(4)$ symmetry, which incorporates both low-lying $0^\pm$ mesons and diquark baryons. We find that all quartic couplings are comparably suppressed when physical values of the pion mass and decay constant are taken as inputs, for which a reasonably smooth chiral symmetry restoration at finite temperature is reproduced. Consequently, mass differences among chiral partners remain small. Despite these tiny mass differences, mass degeneracies of chiral partners in the hot medium are clearly demonstrated, consistent with chiral symmetry restoration. Moreover, we find that the couplings responsible for the $U(1)$ axial anomaly are enhanced upon entering the finite temperature regime. Baryonic fluctuations also provide sizable contributions to these enhancements. Finally, the fate of the topological susceptibility in the hot QC$_2$D medium is examined.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14010
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enhancement of axial anomaly effects in hot two-color QCD: FRG approach in the linear sigma model
Fejős, Gergely
Suenaga, Daiki
High Energy Physics - Phenomenology
High Energy Physics - Lattice
Nuclear Theory
We investigate the thermal properties of hadrons in two-color quantum chromodynamics (QC$_2$D) using the functional renormalization group (FRG) method, with particular focus on modifications of the $U(1)$ axial anomaly effects. The hadrons are described by a linear sigma model (LSM) based on the Pauli-Gürsey $SU(4)$ symmetry, which incorporates both low-lying $0^\pm$ mesons and diquark baryons. We find that all quartic couplings are comparably suppressed when physical values of the pion mass and decay constant are taken as inputs, for which a reasonably smooth chiral symmetry restoration at finite temperature is reproduced. Consequently, mass differences among chiral partners remain small. Despite these tiny mass differences, mass degeneracies of chiral partners in the hot medium are clearly demonstrated, consistent with chiral symmetry restoration. Moreover, we find that the couplings responsible for the $U(1)$ axial anomaly are enhanced upon entering the finite temperature regime. Baryonic fluctuations also provide sizable contributions to these enhancements. Finally, the fate of the topological susceptibility in the hot QC$_2$D medium is examined.
title Enhancement of axial anomaly effects in hot two-color QCD: FRG approach in the linear sigma model
topic High Energy Physics - Phenomenology
High Energy Physics - Lattice
Nuclear Theory
url https://arxiv.org/abs/2506.14010