Nuclear Theory·nucl-th

Wednesday·August 19, 2026

16 papers—5 primary·11 cross-listed

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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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Affiliations

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