Nuclear Theory·nucl-th

Monday·September 8, 2025

12 papers—3 primary·9 cross-listed

01
Nonlocal nucleon-nucleus optical potentials from chiral effective field theory
Laina M. Stahulak🇺🇸 · Jeremy W. Holt🇺🇸
We investigate the nonlocality in microscopic optical potentials derived from chiral effective field theory. For this purpose we employ the Perey-Buck ansatz, which connects the energy dependence of purely local optical potentials to a Gaussian spatial nonlocality. We find that the dominant source of energy dependence in the microscopic real optical potential indeed arises from spatial nonlocalities, while the energy dependence associated with the microscopic imaginary optical potential is a genuine time nonlocality. We present results for nonlocal nucleon-nucleus optical potentials for the calcium isotopic chain and study the dependence of the Woods-Saxon shape parameters on the isotopic number.
nucl-th0 citations
02
rho-Meson Nucleon Scattering Length from CLAS Threshold Photoproduction Measurements
Igor I. Strakovsky (GWU)🇺🇸 · Evgeny L. Isupov (MGU)🇷🇺 · Victor Mokeev (Jlab)🇺🇸 · Axel Schmidt (GWU)🇺🇸
Extending our study of the vector meson-nucleon scattering lengths (summary is given in Ref.~\cite{Strakovsky:2021vyk}), we are focusing on the $ρ$ -meson case using recent CLAS threshold data for the reaction $γ p \to ρp$ within the meson-baryon reaction model~\cite{CLAS:2018drk}. The total $σ_{t} (γ p \to ρp)$ and $σ_{t} (γ p \to ω p)$ cross sections are close below the momentum of the vector meson in CM $q = 0.2 GeV/c$ . Then the $ρp$ photoproduction cross section grows rapidly. Our result for $ρN$ scattering length is a factor of 4 smaller than the size of the hadron and the phenomenological determination of the $ω$ nucleon scattering length using threshold photoproduction cross sections. The observed difference between $ρN$ and $ω N$ scattering lengths is of interest for further understanding within the hadron structure theory.
nucl-thhep-exhep-phnucl-exPRD(2025)·5 citations
03
Ab initio study in the island of inversion within the two-major-shell valence space
X. C. Cao · C. F. Jiao
We present an \textit{ab initio} study of nuclear structure in the island of inversion around neutron number $N = 20$ , using multishell effective Hamiltonians derived from the valence-space in-medium similarity renormalization group approach combined with the quantum-number projected generator coordinate method. By progressively expanding the valence space from the \textit{sd} shell to the intermediate $s d f_{7/2} p_{3/2}$ space and, for the first time, to the full \textit{sdfp} shell, we investigate low-lying spectra, $E 2$ transition strengths, deformation properties, and neutron occupancies in even-even Ne, Mg, and Si isotopes around $N = 20$ . Our results show that enlarging the valence space significantly improves the description of quadrupole collectivity, yielding better agreement with experimental data for key observables such as the lowered $2^{+}$ energies and the enhanced $B (E 2; 0_{1}^{+} \to 2_{1}^{+})$ values. The analysis reveals the critical role of cross-shell multi-particle multi-hole excitations in breaking the $N = 20$ shell closure and establishing intruder-dominated ground states. It also demonstrates the ability of the VS-IMSRG+PGCM framework to capture both dynamical (short range) and static (long range) correlations across multiple major-oscillator shells.
nucl-thPLB(2025)·5 citations
04
New phases in QCD at finite temperature and chemical potential
Masanori Hanada🇬🇧 · Jack Holden🇨🇳 · Hiromasa Watanabe🇯🇵
Understanding the phases of quantum chromodynamics (QCD) at finite temperature and baryon density is crucial for describing matter in heavy-ion collisions and the interior of neutron stars. While the transition from the confined phase to the deconfined phase has been extensively studied at vanishing chemical potential, recent theoretical work suggests the existence of intermediate phases with partial deconfinement, where only a subset of the color degrees of freedom is deconfined. In this paper, we study the generalization of partial deconfinement in QCD in the Veneziano large- $N_{c}$ limit ( $N_{f} / N_{c}$ fixed) to finite baryon chemical potential. We find that the partially deconfined phase has finer structure, and hence that there are four phases in QCD at finite temperature and moderately large chemical potential: complete confinement, complete deconfinement, and two kinds of partial deconfinement. A key ingredient is the refined understanding of the meaning of the 'Gross-Witten-Wadia point', i.e., the opening of a gap in the distribution of Polyakov line phases: either string condensation or baryon condensation causes the GWW transition. As a by-product, we observe the emergence of the QCD critical point from the interplay between baryon condensation and partial deconfinement. While our approach is necessarily qualitative due to the fermion sign problem, it provides a unified theoretical framework for understanding the rich phase structure of dense QCD matter and offers new perspectives on the location and nature of the QCD critical point.
↳ hep-thhep-lathep-phnucl-thPTEP(2026)·5 citations
05
The Three-Body Limit Cycle: Universal Form for General Regulators
Langxuan Chen🇨🇳 · Feng Wu🇫🇷 · Xincheng Lin🇺🇸 · Sebastian König🇺🇸 · Ubirajara van Kolck🇫🇷 · Pengfei Zhang🇨🇳
The Efimov effect, a remarkable realization of discrete scale invariance, emerges in the three-body problem with short-range interactions and is understood as a renormalization group (RG) limit cycle within Short-Range Effective Field Theory (SREFT). While the analytic form of the three-body renormalization relation has been established for a sharp cutoff regulator, its universality for other regulators remains underexplored. In this work, we derive the universal functional form of the three-body renormalization relation for general separable regulators through a detailed analysis of the Skorniakov-Ter-Martirosian and Faddeev equations. We find that the relation follows from a real Möbius transformation characterized by three parameters. This universality is verified numerically for various regulators. Although the functional form remains the same, the parameters characterizing the limit cycle exhibit regulator dependence. These findings broaden the class of RG limit cycles in SREFT and offer a more complete understanding of three-body renormalization.
↳ cond-mat.quant-gasnucl-thphysics.atom-phPRA(2026)·2 citations
06
Parton physics from a heavy-quark operator product expansion: Lattice QCD calculation of the fourth moment of the pion distribution amplitude
William Detmold🇺🇸 · Anthony V. Grebe🇺🇸 · Issaku Kanamori🇯🇵 · C.-J. David Lin🇹🇼 · Robert J. Perry🇺🇸 · Yong Zhao🇺🇸
The pion light-cone distribution amplitude (LCDA) is an essential non-perturbative input for a range of high-energy exclusive processes in quantum chromodynamics. Building on our previous work, the continuum limit of the fourth Mellin moment of the pion LCDA is determined in quenched QCD using quark masses which correspond to a pion mass of $m_{π} = 550$ MeV. This calculation finds $⟨ ξ^{2} ⟩ = 0.202 (8) (9)$ and $⟨ ξ^{4} ⟩ = 0.039 (28) (11)$ where the first error indicates the combined statistical and systematic uncertainty from the analysis and the second indicates the uncertainty from working with Wilson coefficients computed to next-to-leading order. These results are presented in the $MS$ scheme at a renormalization scale of $μ = 2$ GeV.
↳ hep-lathep-phnucl-thPRD(2026)·12 citations
07
Influence of dark matter on hybrid and twin stars
H. C. Das🇮🇹
We investigate the impact of dark matter (DM) on hybrid and twin stars within a two-fluid framework, where DM and normal matter interact only through gravity. A self-interacting fermionic DM model is considered, while for the nuclear and quark matter we employ relativistic mean-field models and the constant sound-speed parameterization, respectively. Solving the two-fluid Tolman-Oppenheimer-Volkoff equations over a five-dimensional parameter space spanning the quark matter transition pressure $p_{t}$ , energy density jump $Δ ϵ$ , sound speed $C_{s}^{2}$ , DM particle mass $m_{χ}$ , and DM fraction $f_{χ}$ , we classify the resulting configurations into hybrid stars and four twin star categories and map the onset properties of the quark phase. The effect of DM on the hybrid and twin star population is regime dependent: the DM particle mass determines whether DM forms an extended halo or a compact core, while the DM fraction sets the magnitude of the effect. In the halo regime, DM enhances quark matter formation and increases the number of hybrid and twin stars; in the core regime, it suppresses them. DM also stabilizes hybrid and twin configurations that are unstable in the pure-baryonic case and systematically pushes the nucleon-to-quark transition to higher densities, with the onset pressure, mass, and radius all rising with the DM fraction, potentially hiding quark matter from current neutron star observations.
↳ astro-ph.HEnucl-thPRD(2026)·2 citations
08
Dissipative contributions to spin polarization
Matteo Buzzegoli🇷🇴
Utilizing the Zubarev non-equilibrium density operator method and a first-order gradient expansion, we provide a comprehensive classification of all possible spin polarization effects. A key finding is that, with the unique exception of those induced by the gradient of the spin potential, all first-order dissipative corrections are chiral, implying their dependence on parity-breaking interactions or chiral imbalance. The work also introduces new non-dissipative phenomena akin to the Spin Hall Effect, including the Chiral Spin Hall Effect, which offers a novel observable to probe QCD topological configurations.
↳ hep-phnucl-thEPJ Web Conf.(2026)·0 citations
09
Reconstruction of the Dipole Amplitude in the Dipole Picture as a mathematical Inverse Problem
Henri Hänninen🇫🇮 · Antti Kykkänen🇺🇸 · Hjørdis Schlüter🇫🇮
We show that the inference problem of constraining the dipole amplitude with inclusive deep inelastic scattering data can be written into a discrete linear inverse problem, in an analogous manner as can be done for computed tomography. To this formulation of the problem, we apply standard inverse problems methods and algorithms to reconstruct known dipole amplitudes from simulated reduced cross section data with realistic precision. The main difference of this approach to previous works is that this implementation does not require any fit parametrization of the dipole amplitude. The freedom from parametrization also enables us for the first time to quantify the uncertainties of the inferred dipole amplitude in a novel more general framework. This mathematical approach to small- $x$ phenomenology opens a path to parametrization bias free inference of the dipole amplitude from HERA and Electron--Ion Collider data.
↳ hep-phmath-phmath.MPnucl-thPRD(2025)·4 citations
10
Tensor-polarized twist-3 parton distribution functions $f_{L T} (x)$ for the spin-1 deuteron by using twist-2 relations
S. Kumano🇨🇳 · Kenshi Kuroki🇨🇳
Tensor-polarized twist-3 parton distribution functions (PDFs) $f_{L T} (x)$ are calculated for the spin-1 deuteron by using twist-2 relations, which are similar to the Wandzura-Wilczek relation and the Burkhardt-Cottingham sum rule in the spin-1/2 nucleon, together with tensor-polarized twist-2 PDFs $f_{1 LL} (x)$ . The PDFs are shown for $f_{L T} (x)$ at $Q^{2} = 2.5$ GeV $^{2}$ , where the tensor-polarized PDFs $f_{1 LL} (x)$ are provided. The $x$ -dependence of $f_{L T} (x)$ is similar to $f_{1 LL} (x)$ , and the magnitude of $f_{L T} (x)$ is roughly of the order of $f_{1 LL} (x)$ . In experiments at the Thomas Jefferson National Accelerator Facility (JLab), higher-twist effects could be sizable because $Q^{2}$ values are not very large in comparison with the hadronic scale of 1 GeV $^{2}$ . Therefore, the JLab experiments could provide a good opportunity to investigate the twist-3 distributions $f_{L T} (x)$ in addition to the twist-2 ones $f_{1 LL} (x)$ . Furthermore, these tensor-polarized PDFs could be investigated at future Electron-Ion Colliders (EICs) and hadron accelerator facilities such as the Fermi National Accelerator Laboratory (Fermilab), the Nuclotron-based Ion Collider fAcility (NICA), and the Large Hadron Collider (LHC).
↳ hep-phhep-exhep-latnucl-ex+1PLB(2026)·6 citations
11
Few is different: deciphering many-body dynamics in mesoscopic quantum gases
Juergen Berges · Sandra Brandstetter · Jasmine Brewer · Georg Bruun · Tilman Enss · Stefan Floerchinger · Keisuke Fujii · Maciej Galka · Giuliano Giacalone🇨🇭 · Qingze Guan · Carl Heintze · Lars H. Heyen and 18 other authors
Emergent macroscopic descriptions of matter, such as hydrodynamics, are central to our description of complex physical systems across a wide spectrum of energy scales. The conventional understanding of these many-body phenomena has recently been shaken by a number of experimental findings. Collective behavior of matter has been observed in \emph{mesoscopic} systems, such as high-energy hadron-hadron collisions, or ultra-cold gases with only few strongly interacting fermions. In such systems, the separation of scales between macroscopic and microscopic dynamics (at the heart of any effective theory) is inapplicable. To address the conceptual challenges that arise from these observations and explore the universality of emergent descriptions of matter, the EMMI Rapid Reaction Task Force was assembled. This document summarizes the RRTF discussions on recent theoretical and experimental advances in this rapidly developing field. Leveraging technological breakthroughs in the control of quantum systems, we can now quantitatively explore what it means for a system to exhibit behavior beyond the sum of its individual parts. In particular, the report highlights how the (in)applicability of hydrodynamics and other effective theories can be probed across three principal frontiers: the size frontier, the equilibrium frontier, and the interaction frontier.
↳ cond-mat.quant-gashep-phnucl-thquant-phEPJA(2026)·4 citations
12
Dispersion relations of deeply virtual Compton scattering: investigating twist-4 kinematic power corrections
Víctor Martínez-Fernández🇫🇷 · Cédric Mezrag🇫🇷
In this paper we include kinematic power corrections up to twist-four to the deeply virtual Compton scattering dispersion relation. We demonstrate that, both for (pseudo-)scalar and spin- $1/2$ targets, the formal expression of the $n$ -subtracted leading-twist dispersion relations is preserved. However, the expression of the subtracted constants is modified by the kinematic powers. Importantly, the minimal-subtracted dispersion relation for the helicity-conserving amplitude, previously thought to depend only on the Polyakov-Weiss $D$ -term, now also depends on the double distributions $F$ and $K$ . These results are consistent with the ones obtained previously in the literature. Such a mixing may be critical for the Jefferson Lab kinematic range, as it is not suppressed for typical values of $t$ and $Q^{2}$ in the valence region. We therefore expect a strong impact on attempts to extract pressure forces from DVCS data.
↳ hep-phnucl-thPRD(2026)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE