Nuclear Theory·nucl-th

Tuesday·May 12, 2026

12 papers—3 primary·9 cross-listed

01
[Submitted on 29 Apr 2026]
Probing Jet-Medium Interactions in Heavy-Ion Collisions Using Energy-Energy Correlators
Rushil Saraswat · Aditya Prasad Dash · Huan Zhong Huang · Gang Wang · Xin-Nian Wang · Zhong Yang
Energy-energy correlators (EECs) provide a sensitive probe of both perturbative and nonperturbative dynamics in relativistic heavy-ion collisions. Jet-medium interactions enhance particle multiplicity within the jet cone, which must be properly accounted for when extracting the EEC of jet shower hadrons in experiments. To address this issue, we develop an augmentation method that exploits momentum conservation between the near-side and away-side regions, using $γ$ -jet events with 0-10\% centrality in Pb+Pb collisions at $s_{N N} = 5.02$ TeV simulated with the CoLBT-hydro model. This approach yields an experimentally reconstructed EEC that shows improved agreement with the EEC of hadrons originating primarily from jet parton splittings. Comparing EECs of jets from Pb+Pb and p+p collisions with different matching conditions can be sensitive to jet medium interaction dynamics, and provide a novel means to test the scenario of jet energy loss in the QGP, followed by fragmentations outside the QGP.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2605.08125 [pdf]
0 citations
02
[Submitted on 6 May 2026]
Modeling $Λ$ polarization in Au $+$ Au collisions at $s_{NN} = 200$ GeV using relativistic spin hydrodynamics
Matteo Buzzegoli🇷🇴 · Aleksandar Gecic🇷🇴 · Rajeev Singh🇷🇴
We investigate spin polarization dynamics in relativistic heavy-ion collisions using ideal relativistic spin hydrodynamics, employing non-boost-invariant longitudinal solutions as the hydrodynamic background. Operating in the small-polarization regime, where spin evolves perturbatively on top of the bulk expansion, we first analyze a $(1 + 1)$ D setup with transverse homogeneity. In this framework, symmetry-constrained initial conditions for the spin potential lead to non-trivial evolution and generate both local and global $Λ$ hyperon polarization consistent with qualitative experimental trends, though they fail to reproduce observed azimuthal structures. To address this limitation, we extend the framework by incorporating transverse flow and spatial anisotropy at freeze-out, constructing a $n o v e l$ $(1 + 1 + 2)$ D model that preserves the longitudinal dynamics. We demonstrate that the inclusion of a longitudinal spin acceleration component, coupled with transverse expansion, results in the emergence of a quadrupole pattern in the longitudinal polarization. The resulting momentum-dependent and integrated observables exhibit qualitative and reasonably good quantitative agreement with experimental data for Au+Au collisions at $s_{NN} = 200$ GeV. Finally, we provide predictions for the in-plane transverse spin polarization, an observable that, to our knowledge, has not yet been experimentally measured.
Comments:
v1: 26 pages; 21 captioned figures; Comments and feedback are welcome; It is possible that we may have missed crucial references, so please let us know; Data created in our analysis is publicly available in the GitHub repository (https://github.com/rs240291/rs-HYDRO). v2: updated discussion, updated references and submitted to journal
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2605.08219 [pdf]
0 citations
03
[Submitted on 11 May 2026]
New perspective on cold fusion reactions: A microscopic description
Yinu Zhang · Bo Han · Yueping Fang · Long Zhu
A microscopic framework that combines the Hartree-Fock-Bogoliubov (HFB) approach with the fusion by diffusion (FBD) model is proposed to investigate the synthesis mechanism of superheavy nuclei (SHN). For the reaction $^{48} Ca +^{208} Pb$ , the calculated evaporation-residue cross section (ERCS) reproduces the experimental data reasonably well. The method enables self-consistent extraction of the fusion injection point and inner barrier from HFB potential-energy surfaces (PES), thereby incorporating nuclear structure effects while eliminating phenomenological tuning at the fusion stage. For cold-fusion reactions, the PES features a hyperasymmetric valley driven by shell effects. This $^{208}$ Pb anchored valley connects the entrance channel to compound nucleus formation and provides an exit channel for cluster decay. We further investigate the cold-fusion reactions $^{54} Cr +^{208} Pb$ and $^{58} Fe +^{208} Pb$ , obtaining a near-exponential decrease of $P_{CN}$ with compound-nucleus charge $Z$ , consistent with established systematics. This approach demonstrates a self-consistent framework that can reduce uncertainties in the fusion stage of SHN production.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2605.10869 [pdf]
0 citations
04
[Submitted on 6 May 2026] (cross-list from hep-ph)
Spiral structure and logarithmic evolution of deuteron form factors: evidence for a transitional regime in QCD
Yaroslav D. Krivenko-Emetov🇦🇹 · Iryna Myroshnykova🇦🇹
We present a consistent analysis of elastic electron--deuteron scattering combining perturbative quantum chromodynamics (pQCD) scaling, helicity amplitudes, and phenomenological parameterizations of deuteron form factors. Particular attention is paid to logarithmic corrections governed by anomalous dimensions of six-quark operators and to two-photon exchange (TPE). Three classes of parameterizations corresponding to different dynamical regimes are considered: pre-asymptotic valence-quark dominance, effective higher-twist contributions, and modified logarithmic evolution. A global fit to the world data for the structure functions $A (Q^{2})$ and $B (Q^{2})$ , differential cross sections, and tensor polarization observables is performed using a combined strategy of global and local minimization. The best description of the complete data set is achieved within the $f_{1}$ parameterization, which incorporates pre-asymptotic logarithmic behavior and correlated valence-quark dynamics. Among the considered models, $f_{1}$ gives the smallest value of $χ^{2} / dof$ . The obtained results indicate that the presently accessible momentum-transfer region corresponds to a transitional regime between hadronic and quark--gluon descriptions. Helicity-conserving amplitudes dominate, whereas the asymptotic pQCD regime has not yet been fully realized. This may indicate nontrivial multiquark correlations related to hidden-color configurations in the short-distance deuteron structure. The tensor polarization observable $t_{21}$ is especially sensitive to the asymptotic behavior of the helicity amplitudes. Future measurements at larger $Q^{2}$ may provide a decisive test for distinguishing between the considered dynamical scenarios.
Comments:
11 pages, 5 figures, 1 table. Proceedings of the XXIV Ukrainian Scientific and Practical Conference "Theoretical and Applied Problems of Physics, Mathematics and Informatics" (Kyiv, May 13-16, 2026) & Contribution to the XXXIII Annual Scientific Conference of the Institute for Nuclear Research (Kyiv, Ukraine, May 25--29, 2026)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.08225 [pdf]
0 citations
05
[Submitted on 8 May 2026] (cross-list from nucl-ex)
Charge radii of Cl isotopes from x-ray spectroscopy of muonic atoms
K.A. Beyer🇩🇪 · T.E. Cocolios🇧🇪 · C. Costache🇷🇴 · P. Demol🇧🇪 · M. Deseyn🇧🇪 · A. Doinaki🇨🇭 · O. Eizenberg🇮🇱 · M. Gorchtein🇩🇪 · M. Heines🇧🇪 · A. Herzáň🇸🇰 · P. Indelicato🇫🇷 · K. Kirch🇨🇭 and 16 other authors
Nuclear charge radii are vital for nuclear and atomic physics, the determination of fundamental constants, and searches for new physics. Muonic atoms, where a single negative muon orbits a nucleus, are sensitive tools for determining nuclear radii due to the large wavefunction overlap of the muon and nucleus. Here we report on a new measurement of the $2, 3, 4 p \to 1 s$ x-ray energies in muonic $^{35, 37}$ Cl with uncertainties reaching 18 ppm. By employing a large-scale germanium detector array, it was possible to extract these energies from a high statistics dataset using highly enriched samples of only a few tens of milligrams. Combining these results with state-of-the-art atomic and nuclear theory input, the charge radii of the stable chlorine isotopes were determined to be $R (^{35} Cl) = 3.3333 (23) f m$ and $R (^{37} Cl) = 3.3444 (23) f m$ . This is an order of magnitude more precise and significantly different from previously tabulated values. Our new values solve a discrepancy observed for the charge radius difference in mirror nuclei, agreeing with the overall global trend. The charge radius difference $δ ⟨ r^{2} ⟩ (^{37} Cl -^{35} Cl) = - 0.0776 (64) f m^{2}$ we extract is 25 times more precise than the previous values. This precision is crucial for establishing reference values for future laser spectroscopy measurements of radioactive isotopes.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2605.08413 [pdf]
2 citations
06
[Submitted on 9 May 2026] (cross-list from gr-qc)
The Good, the Bad, and the Subtle: Relativistic mode sums for neutron-star tidal response
Abhishek Hegade K. R.🇺🇸 · K.J. Kwon · Tejaswi Venumadhav · Hang Yu🇺🇸 · Nicolas Yunes🇺🇸
Time-dependent tidal interactions during the late inspiral of binary neutron stars encode valuable information about neutron-star structure, but systematically extending the familiar Newtonian mode-sum picture into full general relativity is nontrivial. In this paper, we develop a practical relativistic implementation of mode-sum tidal response for non-rotating neutron stars in Regge-Wheeler gauge. Using near-zone boundary conditions, we systematically define the interior tidal field, the relativistic overlap integrals, and the corresponding mode amplitudes. The good is that the dominant f-mode contribution is remarkably robust, reproducing the direct matching calculation to within $\sim 3$ \% across the equations of state we consider. The bad is that the operator governing mode inner product is not positive definite on the full Regge-Wheeler-gauge function space, so the relativistic mode sum truncated at $O (ω^{2})$ is not expected to strictly converge to the direct matching solution. The subtle is that the tidal field inside the star is not unique, although this ambiguity has only a limited impact on the dominant f-mode response for the classes of extensions studied here. Our results establish the practical utility of relativistic mode-sum approximations, while making clear that their predictive power comes from a controlled low-mode description, rather than from a formally convergent strong-field expansion.
Comments:
22 pages, 9 figures. Supplementary notebook in the source file
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2605.08569 [pdf]
7 citations
07
[Submitted on 9 May 2026] (cross-list from astro-ph.HE)
The Non-parametric Equation of State Realizes a Generalized Quark-Hadron Crossover
Yong-Jia Huang🇨🇳 · Shao-Peng Tang🇨🇳 · Yi-Zhong Fan🇨🇳
We propose a non-parametric approach to construct the statistical equation of state (EOS) continuously from the nuclear crust to the asymptotic-freedom regime. The combined requirement of supporting two-solar-mass neutron stars (NSs) with relatively small radii at low masses and of reaching the asymptotically soft pQCD boundary forces a squared-sound-speed ( $c_{s}^{2}$ ) peak followed by extended softening, with $c_{s}^{2}$ returning toward $1/3$ near $\sim 30 n_{sat}$ . Correspondingly, the trace anomaly $Δ \equiv 1/3 - p / ϵ$ becomes positive beyond NS densities and approaches the pQCD limit from above. By quantifying the degree of this softening in the posterior, we find evidence for a hadron-quark transition in the cores of the most massive neutron stars. More importantly, this shows that the thermodynamic structure of a complete crust-to-pQCD statistical EOS naturally realizes a generalized quark-hadron crossover. The quark EOS above NS densities is therefore soft and non-perturbative, in contrast to the stiff quark EOS underlying the quark-star picture.
Comments:
5 + 8 pages, 4 + 6 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2605.08584 [pdf]
2 citations
08
[Submitted on 9 May 2026] (cross-list from hep-ph)
Inferring identified hadron production in $pp$ collisions with physics-informed machine learning at the LHC
Rishabh Gupta🇮🇳 · Kangkan Goswami🇮🇳 · Suraj Prasad🇮🇳 · Raghunath Sahoo🇮🇳
Machine learning has become a powerful tool in high-energy collider experiments, which enables the studies based on data-driven approaches to complex reconstruction and regression tasks. The study of identified hadron spectra in pseudorapidity regions beyond detector acceptance, which is limited to mid-rapidity regions, carries important information about particle production, yet remains unmeasured. In this work, we develop a physics-informed neural network, trained on PYTHIA8 $pp$ collisions at $s = 13.6$ TeV, to infer $p_{T}$ spectra of $π^{\pm}$ , $K^{\pm}$ , $p / p ˉ$ , $Λ/ Λ ˉ$ , and $K_{s}^{0}$ in different rapidity regions. Physics-motivated constraints, including particle yield ratios, spectral shape, and smoothness, are incorporated into the loss function. A staged hyperparameter optimization strategy is used to ensure stability. The model achieves yield uncertainties of $\sim 1.5%$ , $1.8%$ , and $5.83%$ in the training, interpolation, and extrapolation regimes, respectively, outperforming XGBoost and LightGBM. It further reproduces key observables such as particle yield ratios, the multiplicity dependence of $⟨ p_{T} ⟩$ , and kinetic freeze-out parameters, indicating that the model captures the underlying physics and provides reliable predictions beyond the measured phase space.
Comments:
18 pages and 10 captioned figures. Submitted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2605.09022 [pdf]
1 citation
09
[Submitted on 9 May 2026] (cross-list from nucl-ex)
Nuclear charge radii of aluminium isotopes at the proton drip line
Alex Brinson🇺🇸 · Brooke Rickey🇺🇸 · Pierre Arthuis🇫🇷 · Antoine Belley🇺🇸 · Scott Campbell🇺🇸 · Xiangcheng Chen🇺🇸 · Adam Dockery🇺🇸 · Serdar Elhatisari🇹🇷 · Hannah Erington🇺🇸 · Nadeesha Gamage🇺🇸 · Ronald Fernando Garcia Ruiz🇺🇸 · Matthias Heinz🇺🇸 and 26 other authors
Understanding the evolution of nuclear size away from stability remains a central challenge in nuclear physics. In neutron-deficient systems, charge radii can be highly sensitive to the interplay between strong and electromagnetic interactions, and the effects of weak binding, giving rise to exotic nuclear phenomena. However, experimental data on these systems has been limited by short lifetimes and low production rates. Here we report the first laser-spectroscopy measurements of nuclear charge radii along the neutron-deficient aluminium isotopic chain, from $^{25}$ Al to the proton-drip-line nucleus $^{22}$ Al, using the {Resonance Ionization Spectroscopy Experiment} (RISE) at the {Facility for Rare Isotope Beams} (FRIB). Our measurements reveal a step-like increase in charge radius toward the drip line, with similar radii for $^{22, 23}$ Al. A comparison of our results with those of their mirror partners reveals an almost identical correlation with the calculated proton skins and is consistent with the systematic trend of well-bound nuclei. These results offer insight for understanding the evolution of nuclear size at the proton dripline and place important constraints on modern nuclear theory. They also demonstrate the unique combined capabilities of RISE and FRIB to probe the structures of previously inaccessible nuclei at the limits of existence.
Comments:
17 pages, 9 figures, 6 tables Updating to correct author list, added a new reference
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2605.09139 [pdf]
2 citations
10
[Submitted on 10 May 2026] (cross-list from astro-ph.HE)
Cooling of Isolated Neutron Stars with Hyperon-mixed Kaon-Condensation Matter
Bhavnesh Bhat · Akira Dohi · Takumi Muto · Tsuneo Noda
We investigate the thermal evolution of isolated neutron stars containing hyperon--mixed kaon--condensed matter, focusing on the role of proton superconductivity. The equation of state utilized for cooling calculation is based upon the minimal relativistic mean--field framework supplemented by chiral SU(3) dynamics for kaon condensation with an additional component on the three-baryon force, which ensures stiffness at high densities enough to meet astrophysical constraints on neutron-star masses and radii. We show that the nucleonic direct Urca processes operate at relatively low stellar masses ( $M ≳ 1.3 M_{⊙}$ ), erasing any observable signature of strangeness in the absence of superfluidity. However, if the proton $^{1} S_{0}$ superconductivity works, because of suppression of fast neutrino cooling processes, the cooling scenario could become relevant with the strangeness, depending on the density regions of the pairing gap. In particular, if the proton superconductivity is so strong in high-density regions ( $T_{c, p} \sim 1 0^{10} K$ ), the nucleon and hyperon direct Urca processes shut down, which makes the kaon-induced Urca processes dominant in massive neutron stars. This scenario is in good agreement with several cold isolated neutron stars identified recently. Hence, we suggest that strong proton superconductivity can render kaon condensation observationally visible through cold neutron-star observations, providing a potential signature of strangeness in dense matter.
Comments:
19 pages, 13 figures, 1 table
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2605.09723 [pdf]
1 citation
11
[Submitted on 11 May 2026] (cross-list from hep-ph)
Light-front Hamiltonian jet evolution in the Glasma
Dana Avramescu🇫🇮 · Carlos Lamas🇪🇸 · Tuomas Lappi🇫🇮 · Meijian Li🇪🇸 · Carlos A. Salgado🇪🇸
We develop a light-front Hamiltonian formalism to study the real-time quantum evolution of a high-energy quark propagating through the Glasma phase of a heavy-ion collision. In this work, the quark Fock space is truncated to the $∣ q ⟩$ sector and the wavefunction is expanded in a discrete basis representation, following the time-dependent Basis Light-Front Quantization (tBLFQ) framework. The classical Glasma background fields enter as a time-dependent external potential, and physical observables are extracted as expectation values of quantum operators over the time-evolved state. We compute the transverse momentum broadening and the jet quenching parameter, finding results consistent with classical estimates, including the expected scaling with respect to the saturation momentum, and use them to perform phenomenological estimations for different collision systems. We also study the color rotation of the quark state induced by the Glasma fields, and examine its dependence on the saturation scale and the gauge choice. This formalism allows systematic improvements to include, in particular, non-eikonal propagation and parton splittings that will be considered in forthcoming publications.
Comments:
22 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.10413 [pdf]
1 citation
12
[Submitted on 11 May 2026] (cross-list from hep-ph)
RG-Consistent (P)NJL Model: Impact of Thermal Cutoff Modifications on Thermodynamics and Net-Baryon Number Fluctuations
Jie Tang🇺🇸 · Fan Lin🇺🇸 · Xinyang Wang🇺🇸
In this paper, we investigate the impact of renormalization group (RG) consistency on the chiral phase transition and thermodynamic properties of QCD matter using the RGNJL and RGPNJL models. By implementing a temperature-dependent thermal cutoff $Λ_{T} = k Λ_{0}$ , we ensure that thermodynamic quantities converge toward the Stefan-Boltzmann limit at high temperatures, effectively extending the applicability of these effective theories. Our analysis shows that while the RG-consistency condition ( $k \to \infty$ ) resolves causality violations in the RGNJL model by binding the speed of sound to the conformal limit, the RGPNJL model exhibits a more complex, non-monotonic sensitivity to the parameter $k$ . Furthermore, we demonstrate that the RG-improved PNJL framework significantly enhances the description of net-baryon number fluctuations ( $κ σ^{2}$ ) relative to lattice QCD data at vanishing chemical potential, though the intensification of these fluctuations at high baryon density highlights a critical sensitivity to the model's parametric constraints. This study provides a rigorous evaluation of the RG-consistency framework's predictive power in mapping the QCD phase diagram and interpreting experimental observables.
Comments:
13 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2605.10441 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE