Nuclear Theory·nucl-th

Friday·May 8, 2026

12 papers—4 primary·8 cross-listed

05
[Submitted on 30 Apr 2026] (cross-list from hep-ph)
Simplified approach to extracting nucleon transversity in collinear factorization using near-side energy-energy correlators
Zhong-Bo Kang🇺🇸 · Andreas Metz🇺🇸 · Daniel Pitonyak🇺🇸 · Congyue Zhang🇺🇸
We develop a novel strategy for accessing the transversity parton distribution function (PDF) of the nucleon within collinear factorization using near-side energy-energy correlators in the dihadron fragmentation framework. We show how this removes the complications of previous approaches that must model either intrinsic parton transverse momentum or resonances in the invariant mass distribution of a final-state dihadron. We present leading-order analytical results for transverse-spin observables in semi-inclusive deep-inelastic scattering and electron-positron annihilation, highlighting their close similarity to the expressions one uses in extracting (un)polarized PDFs and (single-hadron) fragmentation functions in collinear factorization. We make predictions for kinematics relevant for existing and future facilities that demonstrate the feasibility of an energy-energy correlator program in extracting the transversity PDF.
Comments:
5+3 pages, 3 figures; 3 pages, 2 figures of Supplemental Material; minor edits and typos corrected, remarks added about Jefferson Lab kinematics
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2604.28131 [pdf]
5 citations
06
[Submitted on 6 May 2026] (cross-list from hep-ph)
First next-to-next-to-leading-order extraction of fragmentation functions for Lambda hyperons
Valerio Bertone🇫🇷 · Alessia Bongallino🇪🇸 · Amedeo Chiefa🇬🇧 · Miguel G. Echevarria🇪🇸 · Gunar Schnell🇪🇸
We present MAPFF1.0_Lambda, the first global analysis at next-to-next-to-leading order in perturbative QCD of the collinear unpolarised fragmentation functions of Lambda hyperons. The fit is based on data from single-inclusive electron-positron annihilation, and from both neutral-current and -- for the first time -- charged-current semi-inclusive deep-inelastic scattering. We have adopted a statistical framework based on Monte Carlo sampling and parametrised fragmentation functions in terms of a neural network. The fragmentation function set comprises a total of seven independent parton flavours, allowing for the first independent determination of valence-quark distributions. Our analysis offers new insights into the hadronisation mechanism of strange baryons and establishes a baseline for future phenomenological and experimental investigations.
Comments:
v1: 30 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2605.05314 [pdf]
0 citations
07
[Submitted on 7 May 2026] (cross-list from hep-ph)
Squeezed spectra and back-to-back correlations of protons and antiprotons at RHIC energies
Yong Zhang🇨🇳
This study constrains the range of in-medium mass modification through a comparison of theoretical calculations with experimental transverse momentum spectra and the yield ratio {\bar{p}}/p of protons and antiprotons. Based on the constrained range and a Gaussian source model with radial ow, the theoretical predictions for the fermion back-to-back correlation (fBBC) of p{\bar{p}} pairs at RHIC energies are presented. The results reveal a strong sensitivity of the fBBC signal to the assumed source time distribution: a Lorentzian form generates a pronounced high-momentum signal, whereas an {\alpha}-stable Lévy form leads to a marked low-momentum signal. Moreover, the in-medium mass modification is shown to enhance the yield ratio {\bar{p}}/p. Therefore, events characterized by a larger {\bar{p}}/p ratio are predicted to have a significantly higher probability of exhibiting a detectable fBBC signal. This study may propose a promising new direction for the experimental observation of this phenomenon
Comments:
7 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.05565 [pdf]
PRC(2026)·0 citations
08
[Submitted on 7 May 2026] (cross-list from hep-ph)
Massive hybrid stars within the extended three-flavor quark-meson diquark model
Jens O. Andersen🇳🇴 · Manuel Linares🇳🇴 · Mathias P. Nødtvedt🇳🇴
We discuss the properties of the extended three-flavor quark-meson diquark (EQMD) model as a renormalizable low-energy effective model for QCD. The effective degrees of freedom are quarks, scalar- and pseudoscalar mesons, diquarks, vector- and axial-vector mesons. We calculate the equation of state (EoS) in the mean-field approximation at $T = 0$ imposing charge neutrality for electric and color charges. We match the EoS with a low-density nuclear equation of state. We discuss how the choice of parameters in the model affects the EoS and thereby the mass-radius for hybrid stars. We show that it is possible to construct hybrid stars whose masses and radii are in agreement with recent astrophysical observations and perturbative QCD (pQCD). The addition of vector and axial vector mesons to the quark-meson diquark is essential, since it makes the EoS sufficiently stiff for intermediate densities. Our results suggest that stars with a mass larger than $M \sim 2 M_{⊙}$ have a quark core with a central density $n_{B} \geq 3.9 n_{sat}$ , where $n_{sat} \approx 0.165$ fm $^{- 3}$ is the saturation density. The speed of sound has a double-peak structure and relaxes to the conformal limit from above for large baryon chemical potentials $μ_{B}$ . This structure is caused by the decrease in the mass of the $s$ quark as $μ_{B}$ increases.
Comments:
8 pages, 5 figures, v2: extended discussion on neutron star observations
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2605.05816 [pdf]
PLB(2026)·2 citations
09
[Submitted on 7 May 2026] (cross-list from hep-ph)
A Comparative Study of Mass Extraction Schemes and $π^{\pm} - ρ^{\pm}$ Mixing
Ziyue Wang🇨🇳
We study the origin of the non-monotonic magnetic-field dependence of the lowest charged pion excitation observed in lattice QCD. In a magnetic field, the charged pion mixes with the longitudinally polarized charged rho meson, which shares the same quantum numbers. Within the SU(2) $_{f}$ Nambu--Jona-Lasinio model supplemented by a gauge invariant tree-level $π - ρ$ mixing operator constrained by the experimental $ρ^{\pm} \to π^{\pm} γ$ decay width, we compare four mass-extraction schemes: rest-mass reconstruction, local bosonization, direct determinant solving with Landau projection, and near-pole expansion. The rest-mass scheme cannot reproduce the lattice-type turnover, while in the local derivative-expansion scheme the turnover presence but is weak which occurs at large magnetic field. By contrast, the direct determinant and near-pole schemes both retain a robust non-monotonic lowest mode. The former is most faithful to the Landau-level kinematics of the charged excitation, while the latter most clearly shows that residue suppression enhances the effective mixing after canonical normalization. Our results indicate that the lattice behavior is a genuine quasiparticle mixing effect, but one whose robustness depends crucially on how the charged-meson pole structure is extracted in a magnetic field.
Comments:
27 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.06271 [pdf]
0 citations
10
[Submitted on 7 May 2026] (cross-list from hep-ph)
GTMDs, orbital angular momentum, and pretzelosity
Brean Maynard🇺🇸 · Peter Schweitzer🇺🇸
The leading Generalized Transverse Momentum Dependent parton distributions (GTMDs) are studied in the bag model. The model description is shown to be theoretically consistent. The orbital angular momentum is studied in terms of the GTMD $F_{1, 4}^{q}$ and Ji sum rule. Analytical proofs of the associated sum rules are given. A deeper relationship between orbital angular momentum and the pretzelosity TMD is established in this model.
Comments:
13 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.06412 [pdf]
1 citation
11
[Submitted on 7 May 2026] (cross-list from hep-ph)
Quantum spin dynamics of heavy quarks and polarization observables in relativistic heavy-ion collisions
Sunil Jaiswal🇺🇸 · Sourav Dey🇮🇳 · Amaresh Jaiswal🇮🇳
We develop a quantum spin-density-matrix framework for heavy-quark spin dynamics in relativistic heavy-ion collisions. Starting from an initial polarization induced along the magnetic-field direction, we derive the evolution equation for spin polarization within this framework and obtain analytic solutions. The evolved polarization is connected to open heavy-flavor observables via a fragmentation-based hadronization prescription. For vector mesons, the spin-alignment parameter $ρ_{00}$ is constructed by coupling the heavy-quark spin to that of the light antiquark produced during fragmentation. We confront our results with recent ALICE measurements of prompt $D^{*+}$ spin alignment in Pb--Pb collisions at $s_{NN} = 5.02 TeV$ and extract an effective depolarization strength that determines the spin-relaxation time scale. Using this fitted parameter, we provide benchmark estimates for $Λ_{c}^{+}$ and $Λ ˉ_{c}^{-}$ polarization, up to an overall spin-transfer normalization. We further estimate the recently proposed elliptic polarization harmonic arising from path-length-dependent depolarization in an anisotropic fireball.
Comments:
9 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.06461 [pdf]
2 citations
12
[Submitted on 7 May 2026] (cross-list from hep-lat)
$F_{K} / F_{π}$ as a precision test of a new four flavor Domain Wall Fermion action
Renwick J. Hudspith🇺🇸 · Nicolas Garron🇬🇧 · Zack Hall🇺🇸 · Andrew Hanlon🇺🇸 · Henry Monge-Camacho🇺🇸 · Colin Morningstar🇺🇸 · Amy Nicholson🇺🇸 · Dimitra A. Pefkou🇺🇸 · Thomas R. Richardson🇺🇸 · Fernando Romero-López🇨🇭 · Miguel Salg🇨🇭 · Wyatt A. Smith🇺🇸 and 3 other authors
We present a new set of lattice QCD ensembles with four flavors of smeared Möbius Domain Wall Fermions with good chiral symmetry and small fifth-dimensional extent. A modest amount of computing resources was sufficient to generate 30 publicly-available ensembles spanning five lattice spacings and a broad range of pion masses down to physical. To scrutinize our action we determine $F_{K^{\pm}} / F_{π^{\pm}} = 1.1962 (34)$ , a key quantity for precision CKM unitarity tests, heralding a future of inexpensive high-precision calculations of hadronic observables with chiral fermions.
Comments:
11 pages, 5 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.06560 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE