Nuclear Theory·nucl-th

Monday·January 26, 2026

10 papers—6 primary·4 cross-listed

07
[Submitted on 21 Jan 2026] (cross-list from hep-lat)
Shear and bulk viscosities of the gluon plasma across the transition temperature from lattice QCD
Heng-Tong Ding🇨🇳 · Hai-Tao Shu🇨🇳 · Cheng Zhang🇨🇳
We investigate the temperature dependence of the shear viscosity ( $η$ ) and bulk viscosity ( $ζ$ ) of the gluon plasma using lattice QCD over the range 0.76--2.25 $T_{c}$ , extending from below the transition temperature $T_{c}$ across the transition region and into the deconfined phase. At each temperature, we employ three large, fine lattices, which enables controlled continuum extrapolations of the energy-momentum tensor correlators. Using gradient flow together with a recently developed blocking technique, we achieve percent-level precision for these correlators, providing strong constraints for a model-based spectral analysis. Since the inversion to real-time information is intrinsically ill posed, we extract viscosities by fitting spectral functions whose ultraviolet behavior is matched to the best available perturbative result, while the infrared region is described by a Lorentzian transport peak. The dominant modeling uncertainty associated with the transport peak width is bracketed by varying it over a physically motivated range set by thermal scales. We find that the shear-viscosity-to-entropy-density ratio, $η / s$ , exhibits a minimum near the transition temperature $T_{c}$ and increases for $T > T_{c}$ , whereas the bulk-viscosity-to-entropy-density ratio, $ζ / s$ , decreases monotonically over the entire temperature range studied.
Comments:
16 pages, 10 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2601.14967 [pdf]
PRD(2026)·3 citations
08
[Submitted on 22 Jan 2026] (cross-list from hep-ph)
Axial Anomaly, entanglement and polarization
O.V. Teryaev🇷🇺
The (pion) decays controlled by axial anomaly imply the specific entanglement between photons having also the counterparts for classical electromagnetic waves. This is also a specific case of Eisnstein-Podolsky-Rosen-Bohm-Aharonov effect. The absence of causality and non-locality in (angular) momentum conservation is manifested, being especially clear for the generalization to the case of time rather than space separation corresponds to the polarization of dileptons described by time-like pion transition formfactors which may be studied experimentally. The similar decays in external magnetic field manifest the interplay with vacuum conductivity in external magnetic field and longitudinal polarization of vector mesons observed in heavy-ion collisions.
Comments:
10 pages, no figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2601.16304 [pdf]
PoS(2026)·0 citations
09
[Submitted on 23 Jan 2026] (cross-list from hep-ph)
Thermodynamic geometry in hadron resonance gas model at real and imaginary baryon chemical potential and a simple sufficient condition for quark deconfinement
Riki Oshima🇯🇵 · Hiroaki Kouno🇯🇵 · Motoi Tachibana🇯🇵 · Kouji Kashiwa🇯🇵
The thermodynamic geometry of the hadron resonance gas model with (without) excluded volume effects (EVE) of baryons is investigated. The case with imaginary mu, where mu is the baryon chemical potential, is investigated as well as the one with real mu. We calculate the scalar curvature R and use the R=0 criterion to investigate the phase structure in the mu^2-T plane where T is the temperature. The curve on which R=0 continues analytically from the imaginary mu region, where the lattice QCD is feasible, to the real mu one. In the presence of EVE, there are rich phase structures in the large real mu region as well as the Roberge-Weiss like region where mu is imaginary and a singularity appears, while there is no phase structure in the large real $μ$ region in the absence of EVE. The limitation temperature of the baryon gas is also obtained by using the baryon number fluctuation. The LQCD predicted critical point locates almost on the curve of the limitation temperature we determined. A simple empiric sufficient condition, n_B>1/(2v_B)$, is obtained for the quark deconfinement in the large real mu region, where n_B and v_B are the net baryon number density and the volume of a baryon, respectively.
Comments:
15 pages, 28 figures. :v2 Typos were revised. One sentence was revised: v3 New section 7 is newly added. Typos were revised
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2601.16762 [pdf]
PRD(2026)·1 citation
10
[Submitted on 23 Jan 2026] (cross-list from hep-lat)
Coupled-channel approach to isotensor $π π π$ scattering from lattice QCD
Yuchuan Feng🇺🇸 · Chris Culver🇬🇧 · Michael Döring🇺🇸 · Maxim Mai🇺🇸 · Andrei Alexandru🇺🇸 · Frank X. Lee🇺🇸
The quest to understand three-body dynamics from first-principle QCD includes the study of non-resonant and resonant systems. The isospin $I = 2$ system is of particular interest having no three-body resonance but featuring a resonance in a sub-channel, while also being a coupled-channel problem. In this study, we calculate the finite-volume spectrum from lattice QCD at two different pion masses, map the amplitude to the infinite volume through a generalized Finite-Volume Unitarity (FVU) three-body quantization condition, investigate the limit of a narrow $ρ$ , and compare with an effective Lagrangian prediction at leading order. Chiral extrapolations between different pion masses are performed.
Comments:
30 pages, 13 figures, version accepted by journal
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2601.16916 [pdf]
PRD(2026)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Shear and bulk viscosities of the gluon plasma across the transition temperature from lattice QCD

Axial Anomaly, entanglement and polarization

Thermodynamic geometry in hadron resonance gas model at real and imaginary baryon chemical potential and a simple sufficient condition for quark deconfinement

Coupled-channel approach to isotensor πππ scattering from lattice QCD

Affiliations

Coupled-channel approach to isotensor $π π π$ scattering from lattice QCD