Nuclear Theory·nucl-th

Wednesday·October 1, 2025

13 papers—6 primary·7 cross-listed

01
Shape polarization and coexistence of high- $K$ three-quasiparticle states in odd-mass $N = 106$ isotones
Runyan Dong · Changfeng Jiao
Three-quasiparticle $K$ -isomeric states in odd-mass $N = 106$ isotones within the $A \sim 180$ mass region are systematically investigated using configuration-constrained potential energy surface calculations. The calculations successfully reproduce the excitation energies and deformations of known high- $K$ isomers in the nuclei from $^{175}$ Tm to $^{181}$ Re. For the nuclei closer to the $Z = 82$ shell closure ( $^{183}$ Ir, $^{185}$ Au, and $^{187}$ Tl), predictions for the configurations of observed and yet-to-be-observed isomers are provided. The results reveal strong shape polarization, where the three-quasiparticle states are driven to larger deformations compared to the often shape-soft or spherical ground states. A particularly rich spectrum of shape coexistence is predicted in $^{187}$ Tl, where several high- $K$ three-quasiparticle configurations with distinct prolate, oblate, and triaxial shapes are found to coexist at similar excitation energies. Notably, the oblate-deformed $K^{π} = 29/ 2^{+}$ configuration at $E_{x} = 1839$ keV is proposed to be responsible for a long-lived isomer. This study provides a comprehensive picture of shape evolution and coexistence in high- $K$ multi-quasiparticle states, offering valuable insights for future experimental research.
nucl-thnucl-ex0 citations
02
Pre-equilibrium charm quark dynamics and their impact on D-Meson observables
Manu Kurian🇮🇳 · Mayank Singh🇺🇸 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Björn Schenke🇺🇸
We study the impact of pre-equilibrium evolution on the charm quark $R_{AA}$ and $v_{2}$ in Pb+Pb collisions at $s_{N N}$ = 5.02 TeV. We observe that there is significant diffusion in the pre-equilibrium evolution, but there is no measurable effect on the final state observables.
nucl-thhep-phEPJ Web Conf.(2026)·0 citations
03
Multi-strangeness matter from ab initio calculations
Hui Tong🇩🇪 · Serdar Elhatisari🇸🇦 · Ulf-G. Meißner🇩🇪 · Zhengxue Ren🇨🇳
Hypernuclei and hypernuclear matter connect nuclear structure in the strangeness sector with the astrophysics of neutron stars, where hyperons are expected to emerge at high densities and affect key astrophysical observables. We present the first {\em ab initio} calculations that simultaneously describe single- and double- $Λ$ hypernuclei from the light to medium-mass range, the equation of state for $β$ -stable hypernuclear matter, and neutron star properties. Despite the formidable complexity of quantum Monte Carlo~(QMC) simulations with multiple baryonic degrees of freedom, by combining nuclear lattice effective field theory with a newly developed auxiliary-field QMC algorithm we achieve the first sign-problem free {\em ab initio} QMC simulations of hypernuclear systems containing an arbitrary number of neutrons, protons, and $Λ$ hyperons, including all relevant two- and three-body interactions. This eliminates reliance on the symmetry-energy approximation, long used to interpolate between symmetric nuclear matter and pure neutron matter. Our unified calculations reproduce hyperon separation energies, yield a neutron star maximum mass consistent with observations, predict tidal deformabilities compatible with gravitational-wave measurements, and give a trace anomaly in line with Bayesian constraints. By bridging the physics of finite hypernuclei and infinite hypernuclear matter within a single {\em ab initio} framework, this work establishes a direct microscopic link between hypernuclear structure, dense matter composition, and the astrophysical properties of neutron stars.
nucl-thastro-ph.HEastro-ph.SRhep-lat+19 citations
04
Initial spin fluctuations in heavy-ion collisions and where to find them
Giuliano Giacalone🇨🇭 · Enrico Speranza🇮🇹
Collective spin phenomena in the final states of heavy-ion collisions are typically understood to originate from vorticity and shear in the quark-gluon plasma. Here, we ask whether spin could already be present in the initial condition of the collisions. In particular, we argue that if a spin density exists at the beginning of the QGP expansion, it should experience event-by-event fluctuations due to the finite number of participant nucleons. In this contribution, we propose a simple model of fluctuating spin initial conditions for event-by-event spin hydrodynamics based on the Glauber Monte Carlo paradigm. We postulate that, if the net spin of the events is conserved from the initial to the final state, then initial state fluctuations of spin should manifest in specific spin correlations of $Λ$ hyperons. Within our picture, we predict that this signal is much larger in central O+O collisions than in central Pb+Pb collisions.
nucl-thhep-exhep-phnucl-exEPJ Web Conf.(2026)·0 citations
05
Electromagnetic moments of ground and excited states calculated in heavy odd-N open-shell nuclei
J. Dobaczewski · A. E. Stuchbery · G. Danneaux · A. Nagpal · P. L. Sassarini · H. Wibowo
Within nuclear DFT, we calculated spectroscopic magnetic dipole and electric quadrupole moments for various quasiparticle configurations of odd- $N$ , even- $Z$ , $83 \leq N \leq 125$ nuclei ranging from gadolinium to osmium. By tagging the blocked quasiparticles with single-particle states of the semi-magic dysprosium isotope, we efficiently computed 22 prolate and 22 oblate states for each of the 154 nuclei and tracked them across the entire major neutron shell. We compared this extensive set of theoretical results with experimental data for 82 states in the region. Breaking rotational, time-reversal, and signature symmetries, we aligned the intrinsic angular momenta along the axis of axial symmetry, thereby enabling full shape- and spin-self-consistent polarizations. The spectroscopic moments were then obtained by restoring rotational symmetry. We conducted a detailed analysis of the pattern of agreement and disagreement between theory and experiment in individual nuclei. For the magnetic dipole moments, agreement with the data varies and is characterized by an overall average and RMS deviation of 0.11 $μ_{N}$ and 0.35 $μ_{N}$ , respectively. For the electric quadrupole moments, a good corresponding agreement of 0.16 b and 0.29 b was observed.
nucl-thPRC(2026)·4 citations
06
Nuclear state and level densities of actinides with the shell-model Monte Carlo
D. DeMartini🇺🇸 · Y. Alhassid🇺🇸
Actinides are of great interest in astrophysics and technology applications since they can fission. However, the microscopic calculation of their statistical properties in the presence of correlations poses a major theoretical challenge. The configuration-interaction shell-model is a suitable framework to calculate these properties but the required large model spaces are beyond the reach of conventional diagonalization methods. The shell-model Monte Carlo (SMMC) method enables calculations in very large model spaces and was applied to nuclei as heavy as the lanthanides. Here, we extend the SMMC method to the actinides. Fifteen even-even and odd-mass actinides $^{232}$ Th, $^{234-239}$ U, $^{240-243}$ Pu, $^{246-248}$ Cm, and $^{250}$ Cf are studied using a single-particle model space that is larger than one major shell each for protons and neutrons, with a total dimension of the many-particle space as large as $1 0^{32}$ . We calculate nuclear state densities of these actinides and find they are strongly enhanced in comparison with mean-field densities. We use spin projection methods to calculate nuclear level densities and average $s$ -wave neutron resonance spacings, both of which are found to be in good agreement with experiments.
nucl-th0 citations
07
Nonlocal effective field theory and its applications
P. Wang🇨🇳 · Zhengyang Gao🇨🇳 · Fangcheng He🇺🇸 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸 · Y. Salamu🇨🇳
We review recent applications of nonlocal effective field theory, focusing in particular on nonlocal chiral effective theory and nonlocal quantum electrodynamics (QED), as well as an extension of nonlocal effective theory to curved spacetime. For the chiral effective theory, we discuss the calculation of generalized parton distributions (GPDs) of the nucleon at nonzero skewness, along with the corresponding gravitational (or mechanical) form factors, within the convolution framework. In the QED application, we extend the nonlocal formulation to construct the most general nonlocal QED interaction, in which both the propagator and fundamental QED vertex are modified due to the nonlocal Lagrangian, while preserving the Ward-Green-Takahashi identities. For consistency with the modified propagator, a solid quantization is proposed, and the nonlocal QED is applied to explain the lepton $g - 2$ anomalies without the introduction of new particles or interactions. Finally, with an extension of the chiral effective action to curved spacetime, we investigate the nonlocal energy-momentum tensor and gravitational form factors of the nucleon with a nonlocal pion-nucleon interaction.
↳ hep-phhep-exnucl-thSymmetry(2026)·1 citation
08
Bulk viscosity from neutron decays to dark baryons in neutron star matter
Steven P. Harris🇺🇸 · C.J. Horowitz🇺🇸
The existence of a dark baryon that mixes with the neutron leads to the possibility of neutron decay into a dark sector. Such dark decays have been studied as possibly relevant for the neutron decay anomaly and for their potential impacts on neutron stars. The most popular formulation is a dark sector consisting of a dark baryon $χ$ and a dark scalar $ϕ$ , where a neutron in vacuum decays 1% or less of the time via the channel $n \to χ + ϕ$ . In this work, we consider the effect of this additional neutron decay channel on transport in neutrons star mergers. We find that the neutron dark decay rate in medium is quite slow, and thus the dark baryons modify the dense matter equation of state in a way that decreases the Urca bulk viscosity by, at most, a factor of 2-3. However, if the neutron dark decay was to occur more rapidly, then the bulk viscosity at merger temperatures of tens of MeV would be strongly enhanced, potentially rapidly damping oscillations in merger environments and therefore providing a signature of slowly equilibrating matter in the merger.
↳ astro-ph.HEhep-phnucl-thPRD(2026)·5 citations
09
Machine learning approach to QCD kinetic theory
Sergio Barrera Cabodevila🇪🇸 · Aleksi Kurkela🇳🇴 · Florian Lindenbauer🇦🇹
The effective kinetic theory (EKT) of QCD provides a possible picture of various non-equilibrium processes in heavy- and light-ion collisions. While there have been substantial advances in simulating the EKT in simple systems with enhanced symmetry, eventually, event-by-event simulations will be required for a comprehensive phenomenological modeling. As of now, these simulations are prohibitively expensive due to the numerical complexity of the Monte Carlo evaluation of the collision kernels. In this talk, we show how the evaluation of the collision kernels can be performed using neural networks paving the way to full event-by-event simulations.
↳ hep-phnucl-thEPJ Web Conf.(2026)·1 citation
10
Pre-hydrodynamic jet momentum broadening beyond the jet quenching parameter
Alois Altenburger🇦🇹 · Kirill Boguslavski🇦🇹 · Florian Lindenbauer🇦🇹
We obtain the collision kernel and related dipole cross section during the initial nonequilibrium stages in heavy-ion collisions. These quantities are a crucial input for jet quenching calculations. We further compute the gluon splitting rates in the AMY formalism resulting from this nonequilibrium kernel. Comparing with thermal and commonly used forms, we find that particularly the gluon splitting rate for parton energies of the order of the hard effective temperature significantly differs from these approximations.
↳ hep-phnucl-thEPJ Web Conf.(2026)·0 citations
11
Precision measurement and modelling of the threshold-free 210Pb {\beta} spectrum
Shuo Zhang · Hao-Ran Liu · Ke Han · Xavier Mougeot · Paul-Antoine Hervieux · Tao Sun · Wen-Tao Wu · Robin Cantor · Jing-Kai Xia · Zhi Liu · Jun-Cheng Liang · Fu-You Fan and 4 other authors
Beta decay is a fundamental process that governs nuclear stability and serves as a sensitive probe of the weak interaction and possible physics beyond the Standard Model of particle physics. However, precise measurements of complete $β$ decay spectra, particularly at low energies, remain experimentally and theoretically challenging. Here we report a high-precision, threshold-free measurement of the full $β$ decay spectrum of 210Pb to excited states of 210Bi, using a transition-edge sensor (TES)-based micro-calorimeter. This approach enables the detection of $β$ particle energies from 0 keV up to their endpoint by coincidence summing with subsequent de-excitation energy, thereby eliminating reconstruction artifacts near zero energy that have traditionally limited low-energy spectral accuracy. To our knowledge, this is the first complete, high-precision $β$ decay spectrum from 0 keV. The data resolve theoretical uncertainties associated with the atomic quantum exchange (AQE) effect. An accompanying ab initio theoretical framework, incorporating atomic, leptonic, and nuclear components, predicts a statistically significant (7.2 { $σ$ }) enhancement in $β$ emission probability near zero energy, in agreement with the measurement and in contrast to models that omit AQE corrections. These results provide a new benchmark for $β$ decay theory at low energies, deepen our understanding of the weak interaction, and establish a critical foundation for searches for new physics, including dark matter interactions and precision studies of neutrinos.
↳ nucl-exnucl-thphysics.ins-det1 citation
12
The Physics of Jet Quenching in Perturbative QCD
Yacine Mehtar-Tani🇺🇸
Hard processes in collider experiments typically produce QCD jets, which have long served as precision tests of QCD in the vacuum. More recently, heavy-ion programs at RHIC and the LHC have offered a novel perspective on jets, establishing them as unique probes of strongly interacting matter. Experimental observations, including the suppression of high- $p_{T}$ hadrons and jets, provide compelling evidence for the formation of a new state of matter and its strong coupling to energetic partons. These advances have motivated new theoretical approaches to jet quenching that go beyond standard perturbative techniques, aiming to elucidate the mechanisms of energy dissipation and thermalization of energetic partons in the quark-gluon plasma. This review highlights recent progress, beginning with a unified description of medium-induced radiation across the Landau-Pomeranchuk-Migdal regime and its role in turbulent gluon cascades. We then examine radiative corrections that renormalize the transport coefficient $q^$ , the mechanism of color decoherence in multi-parton systems, and nonlinear QCD evolution equations for jet energy loss. Finally, we confront this framework with experimental measurements, underscoring the need for precision phenomenology to fully exploit the rich data sets from RHIC and the LHC.
↳ hep-phnucl-th21 citations
13
Experimental overview of electromagnetic radiation in heavy-ion collisions
Sebastian Scheid🇨🇭
Electromagnetic (EM) probes such as photons and dileptons provide direct insight into the space-time evolution of the hot and dense matter formed in heavy-ion collisions. Being unaffected by strong interactions, they serve as penetrating messengers from all collision stages, from pre-equilibrium dynamics to the quark-gluon plasma (QGP) and hadronic phases. This contribution summarises recent experimental results on direct-photon and dilepton production from RHIC and LHC experiments, as well as at lower energies. Particular emphasis is given to the ongoing 'direct-photon puzzle', the study of universal scaling of direct-photon production over a large range of collision systems and energies. Recent dielectron measurements from ALICE, STAR, and HADES, as well as new experimental developments at the LHC, are presented, along with perspectives for future facilities.
↳ nucl-exnucl-thEPJ Web Conf.(2026)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE