Dirac spectral density in $N_f=2+1$ QCD at $T=230\mathrm{MeV}$

Journal Article · 30 October 2024 · Physical Review. D.

DOI: https://doi.org/10.1103/PhysRevD.110.074515 · OSTI ID:2475524

Alexandru, Andrei ; Bonanno, Claudio ; D’Elia, Massimo ; Horváth, Ivan

We compute the renormalized Dirac spectral density in $N_f=2+1$ QCD at physical quark masses, temperature $T=230\mathrm{MeV}$ , and system size $L_s=3.4\mathrm{fm}$ . To that end, we perform a pointwise continuum limit of the staggered density in lattice QCD with staggered quarks. We find, for the first time, that a clear infrared structure (IR peak) emerges in the density of the Dirac operator describing dynamical quarks. We also provide numerical evidence that a component of this peak, which becomes dominant in the thermodynamic limit, is due to a nontrivial accumulation of near-zero modes. Features of this structure are consistent with those previously attributed to the recently proposed IR phase of thermal QCD. Our results (i) provide the only complete first-principles evidence that these IR features exist and are physical, (ii) improve the upper bound for IR phase transition temperature $T_{\mathrm{IR}}$ so that the new window is $200<T_{\mathrm{IR}}<230\mathrm{MeV}$ , and (iii) are consistent with the nonrestoration of anomalous ${\mathrm{U}}_{\mathrm{A}}\left(1\right)$ symmetry (chiral limit) below $T=230\mathrm{MeV}$ . Published by the American Physical Society 2024

• Sponsoring Organization: USDOE
• Grant/Contract Number: FG02-95ER40907
• OSTI ID: 2475524
• Journal Information: Physical Review. D., Journal Name: Physical Review. D. Journal Issue: 7 Vol. 110; ISSN PRVDAQ; ISSN 2470-0010
• Publisher: American Physical SocietyCopyright Statement
• Country of Publication: United States
• Language: English