Nuclear Theory·nucl-th

Friday·June 26, 2026

9 papers—6 primary·3 cross-listed

07
[Submitted on 24 Jun 2026] (cross-list from cond-mat.quant-gas)
The odd fermion at the edge: odd-even staggering in the trapped, unitary Fermi gas
Silas R. Beane · Domenico Orlando · Susanne Reffert
We investigate the odd-even staggering in the harmonically-trapped unitary Fermi gas at large particle-number charge $Q$ . Using both a large- $N$ BdG description and a complementary large-charge EFT method, we show that for odd particle number the extra fermion forms an edge-localized quasiparticle near the Thomas-Fermi surface rather than a bulk excitation. In the edge limit, the microscopic BdG problem reduces to a universal coupled Airy system whose lowest positive eigenvalue fixes the leading odd-even splitting energy, $χ ξ^{1/6} (24 Q)^{1/9} ℏ ω + \dots$ where $ξ$ is the Bertsch parameter, and $χ$ is a universal edge coefficient. The associated EFT describes a fermionic mode confined to the boundary and coupled to the superfluid Goldstone field, reproducing the same $Q$ scaling while introducing a dependence on two low-energy constants. Finally, we numerically compute the spectrum and confirm the predicted scaling and localization properties.
Comments:
31 pages, 7 figures
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2606.26225 [pdf]
2 citations
08
[Submitted on 24 Jun 2026] (cross-list from hep-ph)
Axial-Vector Lattice Benchmarks Reveal a Common Medium Response of Meson Screening in Hot QCD
Jie Ren🇨🇳 · Chen Chen🇨🇳 · Fei Gao🇨🇳 · Si-xue Qin🇨🇳
Meson screening masses trace the evolution of hadronic correlations toward quasi-free quark--antiquark screening in hot QCD. Combining lattice QCD (LQCD) benchmarks with a symmetry-preserving Dyson--Schwinger baseline, we identify a flavor-dependent axial-vector quasi-free onset, $x_{f g}^{*} = T_{f g}^{*} / T_{c}$ : an operational high-temperature matching scale at which the axial-vector screening mass has approached the corresponding free-field value after ordinary chiral restoration or parity-partner convergence has set in. On the finite interval $1 \leq x ≲ x_{f g}^{*}$ , independent light/strange and charm-containing lattice benchmarks are organized by a common medium-response function with one flavor-sector parameter. One axial-vector point fixes this parameter; the remaining axial-vector data test its temperature dependence, and vector screening masses validate it without vector input. A reduced-mass interpolation then yields lattice-testable quasi-free onsets and screening spectra for light-charm and bottom-containing sectors. The resulting onset scales provide common reference points for future lattice and continuum studies of meson dissolution across flavor.
Comments:
12 pages, 7 figures, 6 tables
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:
2606.26245 [pdf]
0 citations
09
[Submitted on 24 Jun 2026] (cross-list from hep-ph)
Kinetic freeze-out and diffusion dynamics in small-system asymmetric collisions at sqrt(sNN)=200 GeV in light of a generalized Fokker-Planck distribution
M. Waqas🇨🇳 · Wolfgang Bietenholz🇲🇽 · Khusniddin K. Olimov🇺🇿 · Muhammad Ajaz🇸🇦 · Jihane Ben Slimane🇸🇦 · Laila A. Al-Essa🇸🇦 · A. Haj Ismail🇦🇪
A generalized Fokker-Planck solution is used to examine the transverse momentum ( $p_{T}$ ) spectra of neutral pions generated in small-system asymmetric collisions, $p$ -Al, $p$ -Au, $d$ -Au, and $^{3}$ He-Au, at $s_{N N} = 200$ GeV. This framework provides a cohesive explanation of particle production over a broad range of transverse momenta. We extract the energy scale governing the transition between a thermal and a hard regime, the effective temperature ( $T$ ), and the exponents determining the high-momentum falloff from fits to PHENIX data. $T$ increases systematically with the collision centrality and colliding system size, ranging from about 0.33 GeV in peripheral $p$ -Al collisions to 0.45 GeV in central $^{3}$ He-Au collisions. This increase is correlated with the average number of participant nucleons, $< N_{p a r t} >$ , and the charged-particle pseudorapidity density, $< d N_{c h} / d η >$ , indicating that larger and more central collisions create a denser, more strongly interacting medium that freezes out at a higher temperature. The acquired transition scale and power-law exponents follow consistent patterns across systems and centralities, revealing details about the sharpness of the transition from thermal to hard processes, and the relative strength of momentum-space diffusion versus drag. Interestingly, when the gold target dominates the collision geometry in the largest system ( $^{3}$ He-Au), the transition scale becomes nearly independent of centrality, signifying saturation of the diffusion process. Our findings demonstrate that the generalized Fokker-Planck solution is a sensitive probe of transport properties and non-extensive dynamics in the quark-gluon plasma produced even in small-system relativistic collisions, and it consistently describes pion spectra in this set of collisions.
Comments:
14 pages, LaTex, 4 figures, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2606.26301 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

The odd fermion at the edge: odd-even staggering in the trapped, unitary Fermi gas

Axial-Vector Lattice Benchmarks Reveal a Common Medium Response of Meson Screening in Hot QCD

Kinetic freeze-out and diffusion dynamics in small-system asymmetric collisions at sqrt(sNN)=200 GeV in light of a generalized Fokker-Planck distribution

Affiliations