Nuclear Theory·nucl-th

Tuesday·January 27, 2026

17 papers—7 primary·10 cross-listed

08
[Submitted on 23 Jan 2026] (cross-list from physics.chem-ph)
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.
Subjects:
physics.chem-ph (physics.chem-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2601.17163 [pdf]
J.Chem.Phys.(2026)·1 citation
09
[Submitted on 23 Jan 2026] (cross-list from hep-th)
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.
Comments:
24 pages, 15 figures, 6 tables
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2601.17199 [pdf]
JHEP(2026)·10 citations
10
[Submitted on 23 Jan 2026] (cross-list from nucl-ex)
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.
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2601.17234 [pdf]
PRC(2026)·5 citations
11
[Submitted on 24 Jan 2026] (cross-list from hep-ph)
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.
Comments:
27 pages, 28 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2601.17389 [pdf]
2 citations
12
[Submitted on 25 Jan 2026] (cross-list from hep-ph)
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.
Comments:
12 pages, 9 figures and 5 tables. Accepted by Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2601.17730 [pdf]
PRD(2026)·1 citation
13
[Submitted on 26 Jan 2026] (cross-list from astro-ph.HE)
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.
Comments:
26 pages, 9 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2601.18051 [pdf]
PRD(2026)·0 citations
14
[Submitted on 26 Jan 2026] (cross-list from hep-lat)
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.
Comments:
22 pages, 18 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2601.18354 [pdf]
PRD(2026)·16 citations
15
[Submitted on 26 Jan 2026] (cross-list from hep-ph)
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.
Comments:
to be published in Proceedings of Science (PoS), Proceedings of the 26th international symposium on spin physics (SPIN2025), September 21-26, 2025, Qingdao, Shandong Province, China
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2601.18391 [pdf]
0 citations
16
[Submitted on 26 Jan 2026] (cross-list from hep-ph)
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.
Comments:
to be published in Proceedings of Science (PoS), Proceedings of the 26th international symposium on spin physics (SPIN2025), September 21-26, 2025, Qingdao, Shandong Province, China
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2601.18431 [pdf]
0 citations
17
[Submitted on 26 Jan 2026] (cross-list from nucl-ex)
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.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2601.18688 [pdf]
PRL(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE