Nuclear Theory·nucl-th

Wednesday·August 19, 2026

16 papers—5 primary·11 cross-listed

01
Generative artificial intelligence for reconstructing neutron-star matter
Julia Yu. Panteleeva🇩🇪 · Herzallah Alharazin🇩🇪 · Evgeny Epelbaum🇩🇪
Neutron-star cores hold the only known matter in the universe that is simultaneously cold and strongly interacting, compressed beyond nuclear density into a state of unknown composition. The equation of state links stellar masses, radii and tidal deformabilities to this regime, but recovering this key quantity from sparse observations is an ill-posed inverse problem. Existing analyses bury a prior in a fixed functional form, unevenly weighting admissible solutions and biasing the result. We reconstruct the equation of state with a denoising diffusion model that keeps prior, physics and data separate: it learns an inspectable, physically motivated prior anchored to first-principles nuclear theory, while perturbative-QCD and astrophysical constraints are imposed exactly. Future measurements therefore will update the posterior by reweighting alone, without retraining or resampling. The inferred radius of 12.6 km and tidal deformability of 469 at 1.4 solar masses reproduce Gaussian-process and heavy-ion-informed inferences despite a far broader prior. We find near-conformal but still stiff matter in the heaviest stars, consistent with a gradual hadron-quark crossover and disfavouring a strong first-order phase transition. More broadly, coupling a learned prior to exactly enforced physics establishes a template for ill-posed inverse problems where theory and data constrain different regions.
nucl-thastro-ph.HEastro-ph.IMhep-ph+10 citations
02
Data-Driven Statistical Ensembles of Chiral Nuclear Interactions
Pengsheng Wen · Jeremy W. Holt
Recent advances in ab initio nuclear theory, machine learning, and Bayesian inference, coupled with increasingly precise nuclear experiments and astrophysical observations, have enabled more robust constraints on fundamental descriptions of the nuclear interaction. Although well-established nonlinear regression methods can identify best-fit sets of low-energy constants at fixed resolution scale, they provide limited insight into the full underlying probability distributions of those constants. A central remaining challenge in nuclear theory is therefore to characterize full probability distributions of nuclear forces across resolution scales. In this work, we employ normalizing flows, a class of expressive generative machine learning models, to infer the joint probability distribution of two-body low-energy constants (LECs) in chiral effective field theory over a wide range of resolution scales. The resulting LEC distributions are shown to accurately reproduce experimental neutron-proton scattering phase-shift distributions. Furthermore, strong non-Gaussian correlations among LECs are revealed, indicating a nontrivial interplay among distinct short-range nuclear dynamics. This work establishes a general framework for constructing statistical ensembles of nuclear interactions that can be systematically constrained by future nuclear experiments and astrophysical observations.
nucl-th0 citations
03
Symbolic Regression for Interpretable Emulation of Proton Collective Flow in Intermediate-Energy Heavy-Ion Collisions
Nicholas Cox🇺🇸 · Xavier Grundler🇺🇸 · Bao-An Li🇺🇸
Symbolic regression provides an interpretable machine-learning approach for constructing explicit analytic relations between physical inputs and observables. In this work, we develop symbolic-regression emulators for the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model and compare their performance with deep neural network (DNN) emulators. Using the same transport-model data employed in our previous emulator studies, we show that symbolic regression can reproduce the proton mid-rapidity slope $F_{1}$ of transverse flow $v_{1}$ and elliptic flow $v_{2}$ with accuracy comparable to that of DNNs, while providing explicit analytic expressions and substantially faster prediction once trained. We further demonstrate the use of symbolic regression in the reverse direction by constructing analytic relations that predict the in-medium nucleon-nucleon cross-section modification factor $X$ from the flow observables. Although the symbolic-regression models require substantially longer training times and exhibit greater run-to-run variation than DNNs, their analytic form and rapid evaluation make them promising tools for future transport-model sensitivity and uncertainty analyses.
nucl-thnucl-ex0 citations
04
The elliptic wind on jet wakes in high-energy heavy-ion collisions
Kai-Yi Wu🇨🇳 · Zhong Yang🇺🇸 · Xin-Nian Wang🇨🇳
Energy loss by fast partons induces a Mach-cone-like medium response as they propagate inside the hot quark-gluon plasma (QGP) in high-energy heavy-ion collisions. Because the QGP is nonuniform and its initial gradients generate collective flow, jet-induced medium response in this evolving system is also distorted by the flow and density gradient. This distortion leads to a broadened jet wake whose transverse width depends on the azimuthal angle of the jet propagation due to the elliptic anisotropy of the density gradient and the flow velocity in noncentral heavy-ion collisions. We propose and calculate the difference between the azimuth-dependent jet-hadron correlations for soft charged hadrons in in-plane and out-plane $γ$ -jets as a measure of the elliptic broadening of the wake front and the deepening of the diffusion wake. We also study the sensitivity of this observable to the shear viscosity of the QGP. Experimental measurements of the azimuthal modulation of jet wakes induced by the wind of the elliptic flow at RHIC and LHC can provide additional constraints on the transport properties of the QGP.
nucl-th0 citations
05
Confining density functional approach to the QCD phase diagram at low temperatures and thermal twin stars
David Blaschke🇵🇱 · Oleksii Ivanytskyi🇩🇪
We present a density functional-based equation of state for warm, dense nuclear matter with a transition to deconfined quark matter for applications to simulations of supernova explosions and neutron star mergers, but also for the cosmological evolution of Q-balls. For the quark matter equation of state, we employ a recently developed confining density functional approach while nuclear matter is described within a relativistic density functional model of the DD2 class. The phase transition is obtained by a Maxwell construction at constant entropy per baryon. We discuss the solutions of TOV equations for isentropic hybrid stars for the hybrid equation of state model DDf-SFM (DD2- $χ$ CDF) without (with) color superconductivity and find that at finite temperatures above a critical value of entropy per baryon sequences of disconnected third family branches ("thermal twin stars") may appear for the DDf-SFM model, while they are absent for the color superconducting model and at $T = 0$ . We discuss the relation of this critical entropy per baryon to the Seidov criterion of gravitational instability for $T = 0$ and find that it is a good guide. We suggest that the presence of thermal twin stars may be regarded as an indicator for the core-collapse supernova explodability of massive blue supergiant stars and thus serve as a new criterion for the reliability of hybrid equation of state models. By this argument, strong color superconductivity shall be excluded and it remains to be shown whether models with moderate diquark pairing could fulfill the thermal twin constraint. For the case of symmetric matter, we compare the resulting hybrid EOS with the flow constraint by Danielewicz et al. and find a a sensitivity of the onset density for deconfinement on the presence or absence of color superconductivity.
nucl-thastro-ph.SRhep-ph0 citations
06
Best Reaction Target To Determine Proton Distribution Radii of Atomic Nuclei
Jun-Yao Xu · Bao-Hua Sun · Isao Tanihata · Satoru Terashima · Jian-Wei Zhao · Ji-Chao Zhang · Ge Guo · Shi-Tao Wang · Lei Shen · Jun Su · Xiao-Dong Xu · Andrej Prochazka and 20 other authors
We found that a heavy target such as Pb is most suitable for determining the proton distribution radii of unstable nuclei through charge-changing cross-section ( $σ_{cc}$ ) measurements. As a heavy ion probe, low- $Z$ targets are routinely used to determine nucleon distribution radii of unstable isotopes. This approach has recently been extended to study proton distribution radii from $σ_{cc}$ measurements. However, empirical scaling factors have to be introduced to apply the Glauber models. In the present work, we systematically investigated the scaling factor using 39 new $σ_{cc}$ data of 18 $p$ -shell nuclei on hydrogen, carbon, silver, and lead targets at around 240 MeV/nucleon. Together with the existing data, we reveal a universal dependence of the scaling factor on both the masses of target nuclei and the separation energies of projectile nuclei. The scaling factors decrease with increasing target-nucleus mass and converge to 1 for the highest- $Z$ target, making the scaling unnecessary. We conclude that instead of a low- $Z$ target, employing a heavy target such as Pb in $σ_{cc}$ measurements is the best option to determine the proton distribution radii of unstable nuclei.
↳ nucl-excs.DBnucl-th0 citations
07
Probing the Size of Neutron and Proton Single-Particle Orbitals from Nucleon Knockout Reactions
M. Enciu · A. Obertelli · P. Doornenbal · C. Barbieri · S. Brolli · M. Heinz · W. Horiuchi · T. Inakura · W. H. Long · T. Miyagi · F. Nowacki · K. Ogata and 74 other authors
The size of neutron and proton single-particle orbitals of $^{52}$ Ca, $^{53}$ Ca, $^{54}$ Ca, and $^{55}$ Sc were investigated via nucleon knockout reactions at $\sim$ 230 MeV/nucleon. The determination method is based on the measured fragment momentum distributions in $(p, p n)$ and $(p, 2 p)$ reactions, which are shown to be sensitive to the spatial extension of the wave function of the knocked-out nucleon, interpreted within the distorted wave impulse approximation (DWIA) framework. A systematic sensitivity study is carried out for the $(p, p n)$ recoil-momentum distribution method and is presented in this work. The experimental momentum distributions are compared to state-of-the-art mean field and $ab$ $ini t i o$ in-medium similarity renormalization group and self-consistent Green's function calculations in combination with DWIA reaction theory calculations. Based on this work, the 1 $p$ neutron orbitals are consistently found $0.48 - 0.78$ fm larger than the $0 f_{7/2}$ neutron orbitals in $^{52 - 54}$ Ca, while the size evolution of the valence proton orbitals remains inconclusive due to the large associated statistical uncertainties.
↳ nucl-exnucl-th0 citations
08
Hydrodynamization in 1D Bose gases at nonzero temperature
Jeff Leiberton · Marcos Rigol
Hydrodynamization refers to the remarkably rapid process in relativistic heavy-ion collisions by which hydrodynamic descriptions become applicable. Following the observation of analogous behavior in ultracold one-dimensional (1D) Bose gases, hydrodynamization has been conjectured to be a universal dynamical phenomenon in quantum systems following high-energy quenches. Theoretical studies in this cold-atom setting have so far been restricted to quenches from ground states. Here we study how nonzero temperatures affect hydrodynamization. Specifically, using a homogeneous 1D gas of hard-core bosons, we explore how the initial temperature affects the timescales associated with hydrodynamization and prethermalization following a Bragg-pulse quench. We find that while the hydrodynamization coherence time remains unchanged, increasing temperature shortens both the damping time of the hydrodynamization oscillations and the prethermalization time. We argue that this is mainly the result of the broadening of the initial rapidity distribution, and introduce a nonzero-temperature dephasing time defined in terms of the extent of the rapidity distribution.
↳ cond-mat.quant-gasnucl-thphysics.atom-phquant-ph0 citations
09
Accurate Charge Radius Measurement of $^{14}$ C Confronts \textit{Ab Initio} Theory
Kristian König · Patrick Müller · Tobias Gesser · Emily Burbach · Stefano Gandolfi · Matthias Heinz · Phillip Imgram · Alessandro Lovato · Pieter Maris · Takayuki Miyagi · Wilfried Nörtershäuser · Robert Roth · Julien Spahn · Achim Schwenk
Located at the neutron shell closure $N = 8$ , the long-lived radioactive isotope $^{14}\mathrm{C} $ plays a critical role in geochronology and nuclear structure studies. Despite its widespread use, the nuclear charge radius of $^{14}$ C has remained less precisely known compared to its stable counterpart $^{12}$ C. Here, we report a high-precision determination of the $^{14}$ C charge radius using collinear laser spectroscopy at the COALA setup at TU Darmstadt, improving upon the precision of previous muonic measurements by a factor $5$ and revealing a $1.9 σ$ discrepancy of combined uncertainty, indicating a likely underestimated uncertainty in the muonic determination. This measurement challenges state-of-the-art \textit{ab initio} nuclear theory calculations, including auxiliary field diffusion Monte Carlo, the valence-space in-medium similarity renormalization group, and the no-core shell model, augmented by neural-network techniques. With $^{12}$ C and $^{14}$ C now forming one of the most precisely characterized even-even isotope pairs, these results also enable improved QED tests.
↳ nucl-exnucl-th0 citations
10
The high-energy behavior of tree-level scattering in finite-temperature QCD: estimates of theoretical systematic uncertainty in jet-medium Monte Carlo simulations
Lukas Opitz🇨🇦 · Hemanth Regi🇨🇦 · Gojko Vujanovic🇨🇦
We examine the behavior of tree-level scattering in thermal QCD at high energies and find significant deviations away from the commonly used approximations [Phys. Rev. D 44, 1298 (1991), Phys. Rev. D 44, R2625 (1991), Phys. Rev. D.77, 014015 (2008), Phys. Rev. D. 77.114017 (2008)]. These deviations in the scattering rate also affect jet-medium transport coefficients at the partonic level, leading to a different kinematic dependence of the transverse momentum broadening per unit length $q^$ . As scattering rates and $q^$ are used by large-scale Monte Carlo simulations of jets in the quark-gluon plasma (QGP), such as [Phys. Rev. C 111,054913 (2025)], current constraints on $q^$ are biased owing to the approximations used therein. Besides theoretically improving $q^$ , the differences between the $q^$ herein and the approximate $q^$ used in jet Monte Carlo simulations are used to construct a theoretical systematic uncertainty, which in turn can be employed to devise a covariance matrix for $q^$ and enables updating the uncertainty bands on $q^$ obtained by Bayesian analysis.
↳ hep-phnucl-exnucl-th0 citations
11
Closed-form expressions for tree-level gluon-gluon scattering: a framework for obtaining theoretical systematic uncertainties for jet-medium Monte Carlo simulations
Lukas Opitz🇨🇦 · Hemanth Regi🇨🇦 · Gojko Vujanovic🇨🇦
Modern Bayesian theory-to-data comparisons for jet-medium interactions, such as [Phys. Rev. C 111,054913 (2025)], are lacking the careful accounting of theoretical systematic uncertainties included within their uncertainty budget. Tree-level gluon-gluon scattering is revisited to establish a framework capable of quantifying theoretical systematic uncertainties to be used in Bayesian jet-medium constraints. The behavior of tree-level scattering in thermal QCD is examined in detail, finding deviations away from the commonly used approximations. Deviations in the scattering rate affect jet-medium transport coefficients at the partonic level, leading to a more intricate kinematic dependence for $q^$ and $e^$ than, say, the well-known logarithmic behavior. These deviations away from well-known behavior are used to estimate theoretical systematic uncertainties in Bayesian analysis.
↳ hep-phnucl-exnucl-th0 citations
12
From the universal Lindblad equation to Boltzmann equations: in-QGP quarkonium dynamics
Aoumeur Daddi Hammou🇫🇷 · Pol Bernard Gossiaux🇫🇷
Recently, a set of coupled singlet-octet universal Lindblad equations (ULEs) was derived within the framework of non-relativistic QCD (NRQCD) to describe quarkonium dynamics in the quark-gluon plasma (QGP). These equations provide a unified quantum description spanning the quantum Brownian and quantum optical regimes. In this work, we further develop this framework and establish its connection with semiclassical transport. We first derive the universal Lindblad equations within the potential non-relativistic QCD (pNRQCD) effective field theory and show that they coincide with the small-dipole limit of the NRQCD ULEs. We then derive the semiclassical limit of the NRQCD ULEs, obtaining a set of coupled singlet-octet Boltzmann equations. To our knowledge, this is the first derivation of Boltzmann transport equations directly from the universal Lindblad framework. The resulting equations are valid beyond the small-dipole approximation, allowing the evolution of heavy-quark pairs from compact to widely separated configurations. Taking their small-dipole limit allows a direct comparison with the Boltzmann equations of Yao et al. [Phys. Rev. D 99, 096028 (2019)], which were derived within pNRQCD from the Davies secular equation, relying on the rotating-wave approximation (RWA). While the singlet equations are found to be in near-complete agreement, the octet equation contains an additional collision term describing transitions within the continuum of octet scattering states, which is absent from the RWA-based derivation. Finally, we derive the leading quantum correction to the singlet Boltzmann equation. Our results establish a more general and systematic theoretical foundation for the semiclassical transport description of quarkonium in the QGP.
↳ hep-phhep-thnucl-thquant-ph0 citations
13
Density-induced dark-baryon conversion in $Δ -$ admixed hypernuclear neutron stars
Niyar Prabhat Kalita🇮🇳 · Vivek Baruah Thapa🇮🇳 · Bhanu Prakash Pant🇮🇳 · Anil Kumar🇵🇱 · Partha Konar🇮🇳
We investigate density-induced conversion of neutrons into a neutral dark baryon $χ$ in cold, charge-neutral, $β$ -equilibrated neutron-star matter containing hyperons and all $Δ (1232)$ quartet. The hadronic sector is modeled within a density-dependent covariant density-functional framework using the DDME2 parametrization. A scalar Higgs portal is included as a possible interaction channel between the visible and dark sectors, although its mean-field contribution is negligible for the couplings adopted here. Unlike fixed dark-matter admixture models or scenarios in which nucleon-to-DM conversion is driven by Higgs exchange, the $χ$ abundance is determined self-consistently from chemical equilibrium and baryon-number conservation. We find that hyperons and $Δ$ resonances alter the neutron chemical potential, delay the onset of $χ$ , and suppress its abundance relative to nucleonic matter. This competition induces characteristic changes in the equation of state, particle fractions, sound speed, and adiabatic index. For $m_{χ} = 1250$ , $1300$ , and $1400$ MeV, the maximum masses of the complete $N + Y + Δ + χ$ configurations are $1.806$ , $1.899$ , and $2.024, M_{⊙}$ , respectively, indicating that the massive-pulsar constraint disfavors the lighter dark-baryon benchmarks. The radial profiles further show that for $m_{χ} = 1400$ MeV, $χ$ is confined to the inner core of the most massive stars, while canonical configurations remain essentially unaffected. Thus, the stellar modifications arise primarily from conversion-induced rearrangement of the equilibrium composition rather than from Higgs-mediated interactions. These results highlight the importance of treating conventional non-nucleonic degrees of freedom and density-generated dark baryons on an equal footing when assessing the astrophysical viability of dark-sector extensions of dense matter.
↳ astro-ph.HEhep-phnucl-th0 citations
14
Bound-state spectra of $χ_{c J}$ in finite nuclei and the universal pattern of mass levels
Tian-Le Gao🇨🇳 · Ze-Hua Zhang🇨🇳 · Xiang Liu🇨🇳
In this work, we investigate possible $χ_{c J}$ --nuclear bound states with $J = 0, 1, 2$ using in-medium mass shifts generated by virtual $D^{(*)} D ˉ^{(*)}$ loops within an unquenched framework. The resulting $χ_{c J}$ --nucleus potentials are constructed in the local density approximation, and the bound state spectra are calculated for $^{12} C$ , $^{16} O$ , $^{40} Ca$ , $^{90} Zr$ , $^{197} Au$ , and $^{208} Pb$ . Bound states are obtained for all systems considered. The $χ_{c 0} (1 P)$ and $χ_{c 1} (1 P)$ spectra are nearly degenerate, whereas the larger in-medium mass shift of $χ_{c 2} (1 P)$ leads to deeper binding. Although the absolute bound state energies depend appreciably on the cutoff parameter, the energy differences relative to the $1 s$ level are considerably less sensitive to it and exhibit a regular pattern that decreases approximately as $A^{- 2/3}$ with increasing nuclear mass number. A cosh-type potential with a common nuclear geometry provides a compact description of these spectra. The predicted bound-state structures and level-spacing systematics could be investigated in future high-statistics near-threshold photoproduction experiments at the upgraded JLab facility.
↳ hep-phhep-exnucl-exnucl-th0 citations
15
Revised $^{45}$ V( $p, γ$ ) $^{46}$ Cr reaction rate and its impact on the production of $^{44}$ Ti in core-collapse supernovae
R.S. Sidhu · Y. Luo · C. Sarma · M. Wiescher · X. Xu
The thermonuclear $^{45}$ V( $p, γ$ ) $^{46}$ Cr reaction is the primary leakage pathway from the $^{44}$ Ti-- $^{45}$ V quasi-equilibrium cluster during $α$ -rich freeze-out in core-collapse supernovae (CCSN), governing the final abundance of the $γ$ -ray-emitting isotope $^{44}$ Ti. A recent high-resolution $γ$ -ray study [C. Cousins \textit{et al.}, Phys. Rev. Lett. 136, 252701 (2026)] identified ten previously unknown low-spin proton-unbound states in $^{46}$ Cr, enabling the first experimentally constrained $^{45}$ V( $p, γ$ ) $^{46}$ Cr reaction rate using the AME2020 mass excess, $ME (^{46} Cr) = - 29472 (11)$ ~keV. Here, we adopt the four-fold more precise CSRe mass excess $ME (^{46} Cr) = - 29477.2 (2.6)$ ~keV [M.~Wang \textit{et al.}, Phys. Rev. C \textbf{106}, L051301 (2022)] to recalculate the reaction rate. Including proton capture on the ground and first two excited states of $^{45}$ V alongside new shell-model proton spectroscopic factors, we reduce mass-related rate uncertainties to a subdominant level. The revised rate is up to 69% higher than that of Cousins \textit{et al.} at $α$ -rich freeze-out temperatures ( $T ≃ 1.5$ -- $2$ ~GK). CCSN nucleosynthesis calculations show this revised rate increases the ejected $^{44}$ Ti yield by $\sim$ 26% in a $20 M_{⊙}$ model compared to The \textit{et al.} [ApJ \textbf{504}, 500 (1998)], while causing negligible changes for the SN~1987A trajectory. We demonstrate that $^{44}$ Ti production sensitivity is dictated by the ejecta electron fraction ( $Y_{e}$ ): the reaction significantly affects proton-rich ejecta ( $Y_{e} \approx 0.50$ ) but has little impact on neutron-rich ejecta ( $Y_{e} \approx 0.496$ ), where lower free-proton abundances suppress reaction flow. This reconciles conflicting results from past sensitivity studies.
↳ nucl-exastro-ph.HEastro-ph.SRnucl-th0 citations
16
Three-qubit entanglement in the Bethe-Heitler process
Haotian Cao🇺🇸 · Yuxun Guo🇺🇸 · Yoshitaka Hatta🇺🇸 · Jakob Schoenleber🇩🇪
The familiar Bethe-Heitler process on the proton target $e + p \to e + p + γ$ is transformed into a laboratory for studying multiparticle entanglement. We discuss how bipartite and genuine tripartite entanglement between the final state electron, proton and photon are built up by successive $1 \to 2$ and $2 \to 2$ elementary interactions. We validate our argument by simulating events. Below 5 GeV center-of-mass energy, we identify more than 900 Greenberger-Horne-Zeilinger (GHZ) states and 1200 W states, each with a fidelty exceeding 99%.
↳ quant-phhep-phnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE