Hot QCD matter around the chiral crossover: a lattice study with $O(a)$-improved Wilson fermions

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Auteurs principaux: Krasniqi, Ardit, Cè, Marco, Hudspith, Renwick J., Meyer, Harvey B.
Format: Preprint
Publié: 2024
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author Krasniqi, Ardit
Cè, Marco
Hudspith, Renwick J.
Meyer, Harvey B.
author_facet Krasniqi, Ardit
Cè, Marco
Hudspith, Renwick J.
Meyer, Harvey B.
contents Using lattice QCD simulations with $O(a)$-improved Wilson quarks and physical up, down and strange quark masses, we investigate the properties of thermal QCD matter at the temperatures $T=\{128,154,192\}\mathrm{MeV}$ with a fixed lattice spacing $a=0.064\mathrm{fm}$ and volume $V=(6.1\text{fm})^3$. We find that the pion quasiparticle, defined as the low-energy pole in the two-point function of the axial charge, becomes lighter as the temperature increases and give an argument based on hydrodynamics as to why the pole becomes purely diffusive above the chiral crossover. We study the thermal modification of the isovector vector spectral function using the Backus-Gilbert method, finding an enhancement at low energies and a depletion at energies around $1\mathrm{GeV}$.The analogous study of the axial-vector channel reveals a larger enhancement at energies below $1\mathrm{GeV}$, and we show that these findings are consistent with rigorous spectral sum rules. The difference between vector and axial-vector correlators, an order parameter for chiral symmetry, turns out to be overall suppressed by more than an order of magnitude at the crossover.
format Preprint
id arxiv_https___arxiv_org_abs_2407_01657
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hot QCD matter around the chiral crossover: a lattice study with $O(a)$-improved Wilson fermions
Krasniqi, Ardit
Cè, Marco
Hudspith, Renwick J.
Meyer, Harvey B.
High Energy Physics - Lattice
Using lattice QCD simulations with $O(a)$-improved Wilson quarks and physical up, down and strange quark masses, we investigate the properties of thermal QCD matter at the temperatures $T=\{128,154,192\}\mathrm{MeV}$ with a fixed lattice spacing $a=0.064\mathrm{fm}$ and volume $V=(6.1\text{fm})^3$. We find that the pion quasiparticle, defined as the low-energy pole in the two-point function of the axial charge, becomes lighter as the temperature increases and give an argument based on hydrodynamics as to why the pole becomes purely diffusive above the chiral crossover. We study the thermal modification of the isovector vector spectral function using the Backus-Gilbert method, finding an enhancement at low energies and a depletion at energies around $1\mathrm{GeV}$.The analogous study of the axial-vector channel reveals a larger enhancement at energies below $1\mathrm{GeV}$, and we show that these findings are consistent with rigorous spectral sum rules. The difference between vector and axial-vector correlators, an order parameter for chiral symmetry, turns out to be overall suppressed by more than an order of magnitude at the crossover.
title Hot QCD matter around the chiral crossover: a lattice study with $O(a)$-improved Wilson fermions
topic High Energy Physics - Lattice
url https://arxiv.org/abs/2407.01657