Nuclear Theory·nucl-th

Tuesday·January 27, 2026

17 papers—7 primary·10 cross-listed

01
Quarkyonic matter with strangeness in an extended relativistic mean-field model
Wei Sun🇨🇳 · Cheng-Jun Xia🇨🇳 · Ting-Ting Sun🇨🇳
Quarkyonic matter is expected to play a key role for the transition from hadronic matter to quark matter in compact stars. Within the framework of the relativistic mean-field (RMF) model and equivparticle model with density-dependent quark masses, we construct the ``quark Fermi sea" with a ``baryon Fermi surface" to characterize the properties of the quarkyonic matter. In particular, we develop a comprehensive framework to account for the strangeness degrees of freedom, incorporating $Λ$ , $Ξ$ , and $Σ$ hyperons as well as strange quarks in a unified quarkyonic framework. Our calculations indicate that the inevitable emergence of hyperons softens the equations of state, leading to a reduction in the equilibrium sound velocity around $n_{b} \approx 2 n_{0}$ , and consequently reducing the masses and radii of neutron stars. When the quark-hadron phase transition is taken into account, the equation of state at high densities exhibits additional softening consistent with current astronomical observational constraints. This softening leads to a maximum equilibrium sound velocity of $v_{e q}^{max} \approx 0.6 c$ , which is close to the ultrarelativistic limit of $0.58 c$ .
nucl-thhep-phPRD(2026)·1 citation
02
Two-body cluster entangled structure in the $H_{1} \otimes H_{2}$ Hilbert space
Fei-Long Xu · Xi-Guang Cao · Yu-Gang Ma
This study introduces a quantum information perspective to analyze the internal structure of atomic nuclei, focusing on the quantum entanglement between $α$ clusters in the 0 $^{+}$ state of $^{8}$ Be. A wave function based on angular momentum coupling is developed to transform the two-cluster wave function from the conventional center of mass and relative coordinate basis ( $H_{R_{c . m .}} \otimes H_{r}$ ) into the individual particle basis ( $H_{1} \otimes H_{2}$ ), which is essential for a precise quantification of entanglement. Within this method, the von Neumann entropy is employed to quantify the entanglement arising from the mixing of angular momentum channels. Additionally, we introduce the concept of spatially resolved entropy, which measures entanglement as a function of the radial separation between clusters. Our analysis reveals that the entanglement is strongly correlated with the spatial configuration at the femtometer scale. As the inter cluster separation vanishes, the system approaches a separable $S$ -wave state, indicating that entanglement is dynamically generated during the spatial separation of the clusters. This research provides a new tool for investigating nonlocal quantum correlations in nuclear structure, complementing existing descriptions.
nucl-thPRC(2026)·2 citations
03
Basis Representation for Nuclear Densities from Principal Component Analysis
Chen-Jun Lv · Tian-Yu Wu · Xin-Hui Wu · Gianluca Colò · Kouichi Hagino
We develop an efficient method to represent nuclear densities using basis functions extracted via Principal Component Analysis (PCA). Applying PCA to densities of 75 nuclei calculated with the relativistic continuum Hartree-Bogoliubov (RCHB) theory yields an orthogonal set of components that efficiently capture the dominant features of nuclear density distributions, which can be used as basis functions for nuclear density representation. The first five basis functions account for more than 99.999\% of the total variance, demonstrating the efficiency of these PCA basis functions. The PCA basis achieves significantly higher accuracy and faster convergence than the Fourier-Bessel and Sum-of-Gaussians methods for reconstructing both theoretical and experimental densities. This approach provides an efficient and robust representation of nuclear densities, offering a practical tool for experimental density representation and for theories where densities play a central role, such as the orbital-free density functional theory, or the double folding model for nuclear reactions.
nucl-thnucl-exPLB(2026)·4 citations
04
The role of the surface energy in nuclear octupole excitations
Khlood Alharthi · Paul Stevenson
Octupole excitations of atomic nuclei can be viewed as fluctuations around an equilibrium shape. These fluctuations in turn can be seen as probes of nuclear matter properties to the extent that the shape changes explore changes in compression, surface to volume ratio, or isospin overlap. In the present work we use a series of Skyrme interactions, which were fitted to provide a systematic range of surface energies, to explore the surface energy dependence of octupole excitations in $^{208}$ Pb. We find a strong positive linear corelation between the surface energy of a Skyrme interaction and its prediction of the first $3^{-}$ octupole excitation energy.
nucl-thMod.Phys.Lett.A(2026)·0 citations
05
Meson-exchange currents and nuclear correlations in neutrino and electron scattering with nuclei
Paloma Rodríguez Casalé🇪🇸
This thesis is dedicated to the study of electron and neutrino scattering on nuclei, with special emphasis on meson-exchange currents (MEC) and short-range correlations (SRC) between nucleon pairs in one-particle emission processes. In chapter 2, the SuSAM* model is improved by redefining the single nucleon hadronic tensor, averaging it over a Fermi distribution instead of using the previous extrapolation from the relativistic Fermi gas. This formulation removes the inconsistency associated with negative contributions in kinematics far from the QE peak. The new definition allows extending the SuSAM* formalism to include MEC, which is the focus of chapter 3. In chapter 3, a scaling analysis of 12C data is performed incorporating MEC explicitly at the single nucleon level, leading to a new phenomenological scaling function. Using this model, the effect of MEC on EM responses is studied and compared with the relativistic Fermi gas (RFG) and the relativistic mean field (RMF) models. Chapter 4 presents a detailed analysis of the interference between 1b2b in the RT. It is shown that this interference is always negative within the independent-particle approximation. Chapter 5 extends the study of MEC to the CCQE neutrino scattering within the RFG, RMF, and SuSAM* frameworks. It is found that OB-MEC interference reduces both the RT and the neutrino cross section. Chapter 6 addresses SRC in the wave function of a nucleon pair in nuclear matter. The BG equation is solved using the NN potential developed by the Granada group, allowing for the calculation of high-momentum components. Finally, chapter 7 combined the effect of MEC and SRC, which extends the FG by including the high-momentum components of nucleon pairs affected by MEC. It is found that SRC enhance the RT, in contrast with what is observed in uncorrelated models.
nucl-th0 citations
06
Probability distribution of observables from a Bogoliubov vacuum projected onto good particle number: application to scission configurations of an actinide
Alice Bernard🇫🇷 · David Regnier🇫🇷 · Junah Newsome🇫🇷 · Paul Carpentier🇫🇷 · Noël Dubray🇫🇷 · Nathalie Pillet🇫🇷
Nuclear fission dynamics described within nuclear energy density functional frameworks (EDF) have seen substantial advances in the last decade. Part of this success stems from projection techniques, which allow the computation f probability distribution functions (pdf) for selected observables such as particle number and angular momentum of the fragments. Predicting the pdf of other observables, such as the total kinetic energy of the fragments, remains undone. This work proposes a method to determine the complete pdf of a new category of observables from a Bogoliubov vacuum projected onto good particle number. It relies on sampling nucleonic configurations in coordinate and intrinsic-spin representation. We assess the feasibility and convergence properties of the method and apply it to states representative of the scission of an actinide. Fluctuations in fragment shapes, inter-fragment Coulomb and nuclear interaction as well as the corresponding torques are analyzed. We find that a significant fraction of the fluctuation of several measured fission observables is already present within the mean-field picture.
nucl-thEPJA(2026)·0 citations
07
Role of the symmetry energy on hybrid stars
H. Güven🇫🇷 · K. Bozkurt🇹🇷 · E. Khan🇫🇷 · J. Margueron🇺🇸
The impact of the symmetry energy on the properties of compact stars is analyzed considering constraints from nuclear physics and astrophysics. A compact star can be a neutron star composed only of nuclear matter or a hybrid star with a quark core. Two typical models (soft and stiff) are considered for the nuclear equation of state, and for the hybrid one, a parameterized first-order phase transition approach, completed with a linear quark matter equation of state, is implemented. We show that the phase transition reduces the tension between GW170817 and NICER observations, and we illustrate the impact of the symmetry energy for the understanding of the nature of the binary system in GW170817. We also confirm our previous findings that the GW170817 waveform is best described as a binary HS with a low-density onset of stiff quark matter. This could also be interpreted as a quarkyonic cross-over.
nucl-thastro-ph.HEastro-ph.SRhep-ph1 citation
08
Degenerate coupled-cluster theory
So Hirata
A size-extensive, converging, black-box, ab initio coupled-cluster ( $Δ$ CC) ansatz is introduced that computes the energies and wave functions of states from any degenerate or nondegenerate Slater-determinant references with any numbers of $α$ - and $β$ -spin electrons, any patterns of orbital occupancy, any spin multiplicities, and any spatial symmetries. For a nondegenerate reference, it reduces to the single-reference coupled-cluster ansatz. For a degenerate multireference, it is a natural coupled-cluster extension of degenerate Moeller-Plesset perturbation ( $Δ$ MP) theory. For ionized and electron-attached references, it is a coupled-cluster Green's function, although the present theory is convergent toward the full-configuration-interaction (FCI) limits, while Feynman-Dyson many-body Green's function (MBGF) theory generally is not. Its single-excitation instance is a projection Hartree-Fock theory as per the Thouless theorem, which may be useful for core ionizations, high-spin states, and possibly electron affinities. A new multireference coupled-cluster theory for a general model space is also developed. This quasidegenerate coupled-cluster (QCC) theory is exactly converging, but not black-box, and intended for strong correlation. Determinant-based, general-order algorithms of $Δ$ CC and QCC theories are implemented and compared with configuration-interaction (CI) and equation-of-motion coupled-cluster (EOM-CC) theories through octuple excitations and with $Δ$ MP and MBGF theories up to the nineteenth order. An algebraic, optimal-scaling algorithm of $Δ$ CC theory is computer-synthesized at the levels of single excitations ( $Δ$ CCS) and of single and double excitations ( $Δ$ CCSD). The order of performance is: QCC $\approx$ $Δ$ CC > EOM-CC > CI at the same order or QCC $\approx$ $Δ$ CC > $Δ$ MP > MBGF at the same cost scaling.
↳ physics.chem-phcond-mat.str-elnucl-thJ.Chem.Phys.(2026)·1 citation
09
Entanglement Enabled Tomography of Flux Tubes in (2+1)D Yang-Mills Theory
Rocco Amorosso🇺🇸 · Sergey Syritsyn🇺🇸 · Raju Venugopalan🇺🇸
We investigate the entangling properties of the color flux tube between a static quark-antiquark pair in pure gauge Yang-Mills theory. In earlier works, we defined a gauge-invariant flux tube entanglement entropy (FTE $^{2}$ ), the excess entanglement entropy of a region of gluon fields that can be attributed to the color flux tube, and demonstrated that it is finite in the continuum limit. FTE $^{2}$ was shown to have two contributions, one from the vibrations of the QCD string, and the other from its internal (color) degrees of freedom. In this work, we further explore the internal color component in (2+1)D Yang-Mills theory for $S U (N_{c})$ gauge groups, varying $2 \leq N_{c} \leq 5$ . We identify a novel physical scale in the theory, the entanglement radius $ξ_{0}$ . This radius characterizes the transverse extent of the flux tube that must be completely severed by an entangling region to capture the entanglement entropy of color degrees of freedom. The key feature underlying this phenomenon is its topological nature. This is revealed through systematic studies of multi-slab entangling regions in which FTE $^{2}$ changes sharply when boundaries of the slabs completely cross-cut the flux tube. We find that $ξ_{0}$ increases approximately linearly with $N_{c}$ and is independent of both Rényi replica number and the inter-quark separation length. We also study FTE $^{2}$ as a function of the entangling region's transverse displacement from the static quark pair and observe behavior consistent with a previously identified intrinsic width $λ$ of the flux tube, with an extracted value in agreement with the inverse mass of the lightest glueball for the gauge groups studied.
↳ hep-thhep-lathep-phnucl-thJHEP(2026)·10 citations
10
Longitudinal Dynamics of Large and Small Systems from a 3D Bayesian Calibration of RHIC Top-energy Collision Data
A. Mankolli🇺🇸 · C. Shen🇺🇸 · M. Luzum🇧🇷 · J.-F. Paquet🇺🇸 · M. Singh🇺🇸 · J. Velkovska🇺🇸 · S. A. Bass🇺🇸 · C. Gale🇨🇦 · G. A. C. da Silva🇧🇷 · L. Du🇺🇸 · L. Kasper🇺🇸 · G. S. Rocha🇧🇷 and 44 other authors
A comprehensive Bayesian analysis of the 3D dynamics of high-energy nuclear collisions is presented. We perform a systematic model-to-data comparison using simulations of large and small collision systems, and a broad range of measurements from the PHENIX, STAR, PHOBOS, and BRAHMS collaborations spanning nearly two decades of RHIC operations. In particular, we perform fully 3D multi-stage simulations including rapidity-dependent energy deposition with global energy conservation using the 3D Glauber model, along with relativistic viscous hydrodynamics with MUSIC. We calibrate the model on rapidity- and $p_{T}$ -differential observables and analyze the respective constraints on initial state and transport properties they provide. We emphasize the additional constraints provided by rapidity-dependent measurements, the differences in large and small system calibrations, and the tension exhibited by particular observables. We use our calibrated model to make predictions of observables in p-Au and $^{3}$ He-Au collisions. Furthermore, we facilitate direct comparison of experimental measurements by highlighting the dependence of flow measurements on the rapidity of the regions of interest and reference, as well as the importance of the centrality selection. In particular, we examine the apparent differences between the STAR and PHENIX $v_{2}$ and $v_{3}$ measurements in small systems.
↳ nucl-exhep-phnucl-thPRC(2026)·5 citations
11
Dynamical study of $π N \to π π N$ reactions revisited
H. Kamano🇯🇵 · T.-S. H. Lee🇺🇸
Using the Argonne National Laboratory-The University of Osaka (ANL-Osaka) DCC model of meson-nucleon reactions, we extend the study of Phys. Rev. C 79, 025206 (2009) and Phys. Rev. C 88, 045203 (2013) to predict the cross sections of the $π N \to π π N$ reactions. The model was constructed by fitting only the two-body reactions: $π N, γ N \to π N, η N, K Λ, K Σ$ . Thus, the results for $π N \to π π N$ presented here are predictions of the ANL-Osaka DCC model, which serve to examine the extent to which the forthcoming data from J-PARC can be described. This study provides information for improving the extraction of nucleon resonances that have large decay widths to $π π N$ states. We present results for the total cross sections, invariant mass distributions, and angular distributions. We also identify the observables and energy regions where the higher mass nucleon resonances in the $S_{31}$ , $P_{33}$ , $D_{33}$ , $F_{37}$ , $D_{13}$ , $D_{15}$ , and $F_{15}$ partial waves can be most effectively investigated.
↳ hep-phnucl-th2 citations
12
Production of high-spin $ω_{J} / ρ_{J}$ ( $J = 2, 3, 4, 5$ ) mesons in $π^{-} p$ reactions
Ting-Yan Li🇨🇳 · Zi-Yue Bai🇨🇳 · Xiang Liu🇨🇳
In this work, we perform a comprehensive investigation of the production of high-spin $ω_{J}$ and $ρ_{J}$ mesons ( $J = 2, 3, 4, 5$ ) in $π^{-} p$ reactions using an effective Lagrangian approach. By constructing the relevant $t$ -channel processes and calibrating the model with a single adjustable parameter fitted to existing data, we successfully reproduce the measured total and differential cross sections for the $J = 3$ states $ω_{3} (1670)$ and $ρ_{3} (1690)$ . Within the same framework, we predict the production cross sections for their lower- and higher-spin partners: $ω_{2} (1975)$ , $ρ_{2} (1940)$ , $ω_{4} (2250)$ , $ρ_{4} (2230)$ , $ω_{5} (2350)$ , and $ρ_{5} (2350)$ . Our results show that these states exhibit measurable cross sections with characteristically forward-peaked angular distributions, underscoring their strong potential for observation in future $π p$ meson-beam experiments.
↳ hep-phhep-exnucl-exnucl-thPRD(2026)·1 citation
13
Neutrino opacities in magnetic fields for binary neutron star merger simulations
Mia Kumamoto🇺🇸 · Catherine Welch🇺🇸
Neutrino interactions play a central role in transport and flavor evolution in the ejecta of binary neutron star mergers. Simulations suggest that neutron star mergers may produce magnetic fields as strong as $1 0^{17}$ G, but computational difficulties have hampered the inclusion of magnetic field effects in neutrino interaction rates. In this paper we give approximate interaction rates for neutrinos in the presence of strong magnetic fields, including the effects of Landau quantization and anomalous magnetic moments with errors of order $T / M$ . We also comment on a neutrino production channel from individual neutrons that can produce low-energy $ν ν ˉ$ pairs even at low density.
↳ astro-ph.HEnucl-thPRD(2026)·0 citations
14
Chiral Properties of $(2 + 1)$ -Flavor QCD in Magnetic Fields at Zero Temperature
Heng-Tong Ding🇨🇳 · Dan Zhang🇨🇳
We present a lattice QCD study of the chiral properties of $(2 + 1)$ -flavor QCD in background magnetic fields at zero temperature with physical pion masses. Simulations are performed using the highly improved staggered quark action across four different lattice spacings to enable a controlled continuum extrapolation. We compute the renormalized chiral condensates together with pseudoscalar meson masses and decay constants for pions, kaons, and the fictitious $η_{s s ˉ}^{0}$ pseudoscalar as functions of the magnetic-field strength $e B$ up to $e B ≃ 1.2$ $GeV^{2}$ . The chiral condensates exhibit clear magnetic catalysis, increasing monotonically with the field strength. In the meson sector, neutral pseudoscalar masses decrease steadily with $e B$ , whereas charged pseudoscalar masses display a nonmonotonic response: They rise at small fields, consistent with the lowest-Landau-level expectation, but then saturate and slightly decrease at larger fields, signaling sizable internal-structure effects. At the same time, neutral pseudoscalar decay constants are strongly enhanced by the magnetic field. To quantify deviations from chiral symmetry relations, we isolate the magnetic-field-induced shift in the Gell-Mann--Oakes--Renner corrections and find it to remain small for the neutral pion but to become sizable for the neutral kaon. To elucidate the origin of the magnetic response, we separately analyze the sea- and valence-quark contributions to both neutral and charged meson masses, finding that valence effects dominate at zero temperature. These results provide new insights into the interplay between QCD chiral symmetry breaking and strong magnetic fields.
↳ hep-latnucl-thPRD(2026)·16 citations
15
Tensor-polarized parton distribution functions for spin-1 hadrons
S. Kumano🇨🇳
Spin-1 hadrons contain different aspects of spin physics from the ones of the spin-1/2 nucleon because of the existence of tensor-polarized structure functions. In the charged-lepton deep inelastic scattering from a spin-1 hadron or nucleus, such as the deuteron, there are leading-twist structure functions $b_{1}$ and $b_{2}$ . In addition, there exists a gluon transversity which does not exist in the spin-1/2 nucleon. In the deuteron, these observables could probe interesting dynamical aspects beyond a simple bound system of a proton and a neutron. In addition, there are recent theoretical studies on higher-twist distributions. Tensor-polarized deuteron experiments are now under preparation at the Thomas Jefferson National Accelerator Facility, so that the topic of polarized deuteron is expected to become one of exciting fields in hadron physics. This paper is a brief overview on the tensor-polarized parton distribution functions, including transverse-momentum-dependent parton distributions and fragmentation functions up to twist 4.
↳ hep-phhep-exhep-latnucl-ex+10 citations
16
Nuclear effects on longitudinal-transverse structure function ratio in the deuteron
S. Kumano🇨🇳
Nuclear modifications of the nucleon's structure function $F_{2}^{N}$ have been investigated mainly since the discovery of the EMC nuclear effect in 1983, and there were many experimental measurements from the deuteron to a heavy nucleus. Now, the details of the modifications of $F_{2}^{N}$ are known from small $x$ to large $x$ . On the other hand, it is taken as granted that a nuclear modification does not exist for the longitudinal-transverse structure function ratio $R_{N} = F_{L}^{N} / (2 x F_{1}^{N})$ . However, such a nuclear modification does exist theoretically. A nucleon in a nucleus moves in any space direction, which is not necessary the longitudinal direction along the virtual-photon momentum in charged-lepton scattering. Because of this transverse Fermi motion, the longitudinal and transverse structure functions mix with the mixture probability proportional to the nucleon's transverse-momentum squared $p_{T}^{2} / Q^{2}$ . In this paper, the nuclear modifications are shown numerically for the deuteron by using a standard convolution description. The magnitude of the modifications is of the order of a few percent in the deuteron; however, they should be large in large nuclei. In handling high-energy nuclear data, such nuclear modifications need to be taken into account for a precise determination of physical quantities. Now, the longitudinal-transverse structure-function ratio and tensor-polarized experiments are under preparation for the deuteron at JLab. We hope that such effects will be confirmed experimentally for not only for the deuteron but also for larger nuclei.
↳ hep-phhep-exhep-latnucl-ex+10 citations
17
First observation of multi-phonon $γ$ -vibrations in an odd-odd nuclear system
E.H. Wang🇨🇳 · M. Abushawish🇫🇷 · J.H. Hamilton🇺🇸 · A. Navin🇫🇷 · S. Bhattacharyya🇮🇳 · J. Dudouet🇫🇷 · G. H. Bhat🇮🇳 · J.A. Sheikh🇮🇳 · S. Jehangir🇮🇳 · S.Y. Wang🇨🇳 · S. Sun🇨🇳 · B. Qi🇨🇳 and 18 other authors
The identification of the first multi-phonon $γ$ -vibrational bands in an odd-odd neutron-rich nucleus of the nuclear chart is presented. These high spin structures of hard to access $_{41}^{104}$ Nb $_{63}$ , produced in fission, were studied by combining a spectrometer with isotopic resolution coupled to a $γ$ -ray tracking array and independently high-fold $γ$ coincidence measurements. Triaxial Projected Shell Model calculations for the high-spin states are in good agreement with the measured observables for the yrast, one-phonon and two-phonon $γ$ bands. The possibility of an oblate shape of an isomeric state and coexistence of triaxial and oblate configurations are investigated from the decay of the 141 keV isomer. The present work illustrates the robustness of vibration excitations in the presence of odd valence proton and neutron as well as the possibly coexisting shapes beyond the $N = 60$ transitional region.
↳ nucl-exnucl-thPRL(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE