Nuclear Theory·nucl-th

Tuesday·June 30, 2026

21 papers—12 primary·9 cross-listed

13
[Submitted on 26 Jun 2026] (cross-list from hep-ph)
Soft Contributions Stabilize NNLO QCD Corrections to Quarkonium Production and Decay
Luca Maxia🇫🇷 · Hua-Sheng Shao🇫🇷 · Lukas Simon🇫🇷 · Guoxing Wang🇫🇷
Next-to-next-to-leading order (NNLO) QCD corrections to quarkonium production and decay are known to exhibit perturbative instabilities within non-relativistic QCD. We identify the origin of this problem and propose a simple remedy. Applying our approach to $S$ -wave color-singlet quarkonium processes, we achieve substantially improved perturbative convergence and agreement with experimental data.
Comments:
16 pages, 7 figures, 2 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2606.28494 [pdf]
1 citation
14
[Submitted on 26 Jun 2026] (cross-list from hep-ph)
Polarization interference in exclusive $V +$ jets at all orders in $α_{s}$
Trina Basu🇵🇱 · Richard Ruiz🇵🇱
Using new methods for computing helicity amplitudes with intermediate helicity-polarized gauge bosons, we revisit the transverse-longitudinal polarization interference in the $pp \to V + jets$ process for $V = γ^{*}, Z^{(*)}, W^{(*)}$ decaying to massless leptons. At each order of the strong coupling constant $α_{s}$ and remaining exclusive with respect to jet kinematics, we show that the polarization interference in $γ^{*} \to ℓ^{+} ℓ^{-}$ vanishes after phase-space integration over the kinematics of $ℓ^{\pm}$ , thereby extending well-known results for the inclusive process. Due to parity violation, cancellations are softened for the $W$ and $Z$ bosons. We give a simple formula to account for fiducial cuts. We comment on the implications for multiboson processes, and the applicability of our results to chiral gauge bosons in new physics scenarios and to polarization measurements of weak bosons in heavy ion collisions.
Comments:
8 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2606.28496 [pdf]
0 citations
15
[Submitted on 26 Jun 2026] (cross-list from hep-th)
Dynamically Generated Fermi Surface Mismatch and Relativistic Superfluidity in a Two-Component Massless Fermionic Theory
Susobhan Mandal🇮🇳 · Sambuddha Sanyal🇮🇳
When fermions pair across mismatched Fermi surfaces, the mismatch reflects a built-in inequivalence between the species. We show it can instead arise dynamically by spontaneous symmetry breaking. In a massless two component Dirac theory with exact SU(2) flavor symmetry, a self-interacting vector boson condenses, splitting the Fermi surfaces while preserving time reversal. Pairing then yields a stable relativistic superfluid, promoting the Chandrasekhar-Clogston line to a surface in coupling space, the mismatch fixed self-consistently by the symmetry-breaking coupling.
Comments:
4.5 pages, 1.5 pages end matter, 36 pages supplementary
Subjects:
High Energy Physics — Theory (hep-th); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
arXiv:
2606.28550 [pdf]
0 citations
16
[Submitted on 27 Jun 2026] (cross-list from hep-ph)
Effects of Mirror Dark Matter on Neutron-Star Structure and Tidal Deformability
Jin-Cheng Jiao🇨🇳 · Cheng-Ming Li🇨🇳
Mirror dark matter (MDM) can modify neutron-star structure and tidal response through gravitational coupling. In this work, we construct an ordinary-matter equation of state (EOS) by comparing hadronic matter described by the relativistic mean-field NL3$\omega\rho$ model, and quark matter in the framework of the Nambu--Jona-Lasinio (NJL) model. The stable branch is determined through a Maxwell construction, which serves to connect distinct phases of matter. For the parameter sets considered here, $m_u=5.2~{\rm MeV}$ is the lowest light current-quark mass in the scanned range that satisfies the $2M_\odot$ maximum-mass requirement, while $m_u>5.2~{\rm MeV}$ all yield stable neutron-star configurations without a resolved macroscopic quark core. The small-radius inferences for PSR J0437--4715 and XTE J1814--338, together with the tidal-deformability constraint from GW170817, are sensitive to the dark-matter mass fraction $f_D$. The commonly used GW170817 interval $70\lesssim\Lambda_{1.4}\lesssim580$ corresponds approximately to $0.12\lesssim f_D\lesssim0.88$ in the present model. These results indicate that, even without a macroscopic quark core, MDM can provide an important mechanism for reducing the visible radius and modifying the tidal response of neutron stars.
Comments:
12 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2606.28934 [pdf]
0 citations
17
[Submitted on 27 Jun 2026] (cross-list from nucl-ex)
Dineutron clusters
Takashi Nakamura · Kouichi Hagino · Yosuke Kondo
The dineutron is a spatially compact two-neutron cluster, which is expected to appear in a low-density part of nuclei. In recent years, there has been rapid progress in experimental and theoretical research on dineutron clusters, particularly on neutron-rich rare isotopes. Experimentally, evidence for dineutron in two-neutron halo nuclei, such as $^{11}$ Li, has been obtained using Coulomb breakup, measurements of charge radii, and quasi-free proton scattering. Specific unbound nuclei just beyond the neutron drip line, which decay by emitting two neutrons, are also candidates for having a dineutron correlation. For instance, the dineutron structure has recently been investigated for $^{16}$ Be, focusing on its decay into the core and the two neutrons. Theoretically, it is shown that the dineutron is partially due to the admixture of different-parity configurations for the two valence neutrons. Few-body theories, including dynamical effects of the decay process, play important roles in interpreting three-body decays. We also discuss the four-neutron clusters, showing the experimental results of recent tetraneutron experiments and observation of $^{28}$ O. Possible relevance of these states to dineutron correlation is discussed. Finally, we discuss future perspectives on dineutron clusters in neutron-rich nuclei and their relation to the universal features in few-body physics.
Comments:
54 pages. To appear in Eur. Phys. J. A
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2606.28950 [pdf]
EPJA(2026)·2 citations
18
[Submitted on 27 Jun 2026] (cross-list from hep-ph)
Equilibrium Statistics as Conditional Laws and Conservation-Induced Correlations
Sunil Jaiswal🇺🇸 · Amaresh Jaiswal🇮🇳
We present a novel unified conditional-probability framework for relativistic systems in which conditioning on additive conservation laws simultaneously yields equilibrium occupation statistics and conservation-induced correlations. In this formulation, equilibrium arises as a conditional limit law of a closed system. The one-mode marginal gives Maxwell--Boltzmann, Bose--Einstein, and Fermi--Dirac statistics at leading saddle order, with the conserved quantities fixing the exponential tilt and the microscopic occupation measure determining the statistics. Expanding the two-mode marginal to Gaussian order gives the leading finite-rank covariance between modes induced by exact conservation. When contracted with observables linear in mode occupations, this covariance gives their leading exact-conservation contribution. We use this structure to define projected observables orthogonal to selected conserved quantities. By construction, their covariance has no leading exact-conservation contribution. In small collision systems, where conservation effects are less suppressed by multiplicity and can survive standard nonflow suppressions, this provides a direct way to isolate conservation-aligned contributions to long-range correlations. We demonstrate this with PYTHIA8/Angantyr-generated p+Pb events at $s_{NN} = 5.02 TeV$ by comparing ordinary and projected covariances, showing that the projection removes the conservation-aligned contribution while leaving the conservation-orthogonal covariance essentially unchanged.
Comments:
6 pages, 1 figure; Supplemental Material included
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2606.29050 [pdf]
1 citation
19
[Submitted on 29 Jun 2026] (cross-list from hep-ph)
Soft-Radiation-Induced Decoherence of Heavy-Quark Spin Entanglement at the Electron-Ion Collider
Sanskriti Agrawal🇮🇳 · Muneeb Zahoor🇮🇳 · Raktim Abir🇮🇳
Using the soft-gluon theorem, we identify a soft-recoil mechanism by which unresolved gluon radiation induces decoherence in the spin correlations of heavy quark-antiquark pairs produced in deep-inelastic scattering. We show the eikonal soft contribution preserves the Born spin structure, whereas the subleading soft term generates stochastic recoil-induced rotations of the spin-correlation plane. Upon tracing over the unresolved gluon, these rotations produce an effective dephasing channel: the normal-axis correlation remains unchanged at this order, while the in-plane spin coherences are suppressed. We estimate the resulting reduction of concurrence and Bell-CHSH violation, and propose a radiation-binned EIC observable based on the ratio of in-plane to normal spin correlations. This observable isolates the characteristic anisotropic suppression predicted by the soft-recoil mechanism and provides a measurable handle on radiation-induced spin decoherence of an entangled quark-antiquark pair produced in a deep-inelastic scattering process.
Comments:
24 pages, 1 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2606.29944 [pdf]
3 citations
20
[Submitted on 29 Jun 2026] (cross-list from hep-th)
Nonlinear nature of near-equilibrium viscous fluids
Yan Liu🇨🇳 · Hao-Tian Sun🇨🇳
We study the late-time relaxation of a neutral relativistic viscous fluid in $d + 1$ dimensions. In the long-wavelength regime, linearized hydrodynamics predicts that the sound mode at momentum $nk$ decays as $e^{- n^{2} ω_{I} t}$ . However, nonlinear analysis gives a decay of $e^{- n ω_{I} t}$ . We derive a closed asymptotic attractor solution in which the frequency of the $n$ -th harmonic locks to $n$ times the complex frequency of the fundamental mode. The amplitude envelopes for energy current $J$ obey a simple cascading relation, $J_{n} = α_{J}^{n - 1} J_{1}^{n}$ , with $α_{J}$ fixed by the equation of state, the longitudinal viscosity, and the fundamental wavenumber. For conformal fluids, $α_{J} = 1/ (8 η k)$ , in agreement with the holographic result of arXiv:2512.07242. The existence of the attractor shows that, even near equilibrium, field powers are not equivalent to amplitude order.
Comments:
19 pages
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); nlin.CD (nlin.CD); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2606.30043 [pdf]
0 citations
21
[Submitted on 29 Jun 2026] (cross-list from hep-lat)
Isospin-Driven Splitting of Chemical Potentials in Isobar Collisions from Lattice QCD
Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Jia Ni🇨🇳
Strong magnetic fields produced in relativistic heavy-ion collisions can modify fluctuations of conserved charges and, consequently, their associated chemical potentials. We present first-principles $(2 + 1)$ -flavor lattice-QCD results for isospin-driven splittings of conserved-charge chemical potentials between the isobar systems $_{44}^{96} Ru +_{44}^{96} Ru$ and $_{40}^{96} Zr +_{40}^{96} Zr$ in the QCD crossover region, both at vanishing and nonzero magnetic fields along the pseudo-critical line $T_{p c} (e B)$ . We outline a framework that, under strangeness neutrality and charge-to-baryon ratio $r \equiv n_{Q} / n_{B}$ , maps the isospin difference between two nuclei, as encoded in $r_{Zr}$ and $r_{Ru}$ , onto splitting ratios $Δ μ_{Q} /Δ μ_{B}$ , $Δ μ_{S} /Δ μ_{B}$ , and $Δ μ_{S} /Δ μ_{Q}$ as functions of $μ_{B} (r_{Ru}) /Δ μ_{B}$ . Using continuum-estimated lattice results for the leading-order coefficients $q_{1} \equiv (μ_{Q} / μ_{B})_{LO}$ and $s_{1} \equiv (μ_{S} / μ_{B})_{LO}$ , we find that, at vanishing magnetic field, the splitting ratios are of similar magnitude to recent Bayesian extractions from STAR isobar data and yield $Δ μ_{Q} < 0$ and $Δ μ_{S} > 0$ , with the electric-charge sector dominating. At nonzero magnetic fields, the splitting ratios show only moderate $e B$ dependence. We therefore further examine Ru--Zr differences in the normalized magnetic-field response of chemical-potential ratios, particularly those involving $μ_{Q} / μ_{B}$ , which display a pronounced enhancement in lattice QCD. We also present hadron resonance gas (HRG) results and experimentally motivated proxy observables with kinematic cuts to facilitate contact with experiment.
Comments:
15 pages, 7 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2606.30164 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE