Nuclear Theory·nucl-th

Tuesday·January 6, 2026

11 papers—5 primary·6 cross-listed

01
Neutron skins probed in proton knockout from neutron-rich nuclei
C.A Bertulani🇺🇸 · R.V. Lobato🇧🇷
Proton-induced quasifree knockout reactions provide a powerful probe of nuclear single-particle structure and reaction dynamics in both stable and neutron-rich nuclei. In this work we develop a unified theoretical framework for the calculation of inclusive (p,2p) and sequential (p,3p) reaction cross sections and fragment momentum distributions at intermediate and relativistic energies. The approach is based on a probabilistic extension of Glauber multiple-scattering theory combined with microscopic nuclear densities obtained from Hartree-Fock-Bogoliubov calculations using Skyrme energy-density functionals. We focus in particular on the sensitivity of total cross sections and longitudinal momentum dispersions to neutron-skin thickness along isotopic chains. Our results indicate that both (p,2p) and (p,3p) reactions exhibit a systematic decrease of cross section and momentum width with increasing neutron excess, reflecting enhanced attenuation and surface bias induced by neutron skins. The effect is significantly stronger for two-proton removal, suggesting that (p,3p) reactions may offer enhanced sensitivity to isovector nuclear structure. These findings establish proton-induced knockout reactions as complementary hadronic probes of neutron skins and the density dependence of the nuclear symmetry energy.
nucl-thPRC(2026)·2 citations
02
Microscopic Description of Rotational Nuclear Fission Elucidates Fragment Spin Generation and Scission Mechanism
Yu Qiang · Zhibo Li · Junchen Pei
The generation of fission fragment spin as a probe of scission mechanism remains a question of considerable interests. We present here microscopic calculations of rapidly rotating fission of the compound nucleus 240Pu under varying initial conditions within the time-dependent density functional theory framework. The obtained spin ratio of light to heavy nascent fragments is unchanged up to high spins but diminished as excitation energies increase, indicating sawtooth structures in fragment spins would fade away at high excitations rather than high angular momentum. Further analysis elucidates that the bending scission mode is predominated at low excitation energies, which has been under intense debates. Results also show thicker and elongated neck configurations, along with scission nucleons emitted perpendicular to the fission axis, owing to rapid rotations. These findings offer insights into the scission mechanism of rotating compound nuclei that have usually been overlooked in earlier studies.
nucl-th1 citation
03
Comment on QED Corrections to the Parity Violating Asymmetry in High-Energy Electron-Nucleus Scattering
Brendan T. Reed🇺🇸 · C. J. Horowitz🇺🇸
In a recent letter Roca-Maza and Jakubassa-Amundsen claim a large $\approx 5%$ radiative correction to the parity-violating asymmetry $A_{p v}$ in electron-nucleus scattering. If true, this would be important for the interpretation of the PREX, CREX, and MREX experiments. However, Roca-Maza and Jakubassa-Amundsen do not explicitly include the axial-vector vertex correction to $Z^{0}$ exchange (at the momentum transfer of the experiment). We show that including this cancels much of the change in $A_{p v}$ .
nucl-thhep-phnucl-ex5 citations
04
Searching for the Tetraneutron Resonance on the Lattice
Linqian Wu🇨🇳 · Serdar Elhatisari🇸🇦 · Ulf-G. Meißner🇨🇳 · Shihang Shen🇨🇳 · Li-Sheng Geng🇨🇳 · Youngman Kim🇰🇷
The nature of the tetraneutron ( $4 n$ ) system remains a pivotal question in nuclear physics. We investigate the $4 n$ system using nuclear lattice effective field theory in finite volumes with a lattice size up to $L = 30$ ~fm, employing both a high-precision N $^{3}$ LO interaction and a simplified SU(4) symmetric one. The ground-state energy is found to decrease smoothly with increasing box size, showing no plateau characteristic of a resonance. We further compute the dineutron-dineutron scattering phase shift using Lüscher's finite-volume method. At the smallest relative momenta, the extracted $2 n$ -- $2 n$ $S$ -wave phase shift is small, consistent with a weak interaction in the dilute limit. At intermediate momenta, it exhibits a weak attraction with a peak of approximately $1 0^{\circ}$ at relative momentum of 60--84~MeV. While this structure does not constitute a resonance, the corresponding confined $4 n$ energy of 1.7--3.3~MeV lies close to the experimentally observed low-energy peak.
nucl-thPRL(2026)·5 citations
05
Exploring bound states and interactions of the nucleon-antinucleon system in a constituent quark model
Aaron Park🇰🇷 · Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷
In this work, we study the nucleon-antinucleon system in a constituent quark model. We first construct the nucleon-antinucleon wave function such that the multiquark and multiantiquark components each satisfy the Pauli exclusion principle, and then investigate the possibility of a bound state using a Hamiltonian that includes color-color, spin-dependent interactions and three-quark potentials. Our results indicate that, in specific channels, the nucleon-antinucleon interaction exhibits significant attraction, suggesting a strong possibility of a bound state.
nucl-thhep-ph0 citations
06
Investigating $Ω ϕ$ Interaction and Correlation Functions
Ye Yan · Yuheng Wu · Yue Tan · Qi Huang · Hongxia Huang · Jialun Ping
In this work, we investigate the interaction between the $Ω$ baryon and the $s s ˉ$ meson within the framework of the quark delocalization color screening model. The spectra calculations show that no bound state is formed in any of the considered channels, while the scattering indicates that the $Ω ϕ$ interaction with $J^{P} = 1/ 2^{-}$ is weakly attractive. As for the $Ω ϕ$ interactions with $J^{P} = 3/ 2^{-}$ and $5/ 2^{-}$ , as well as the $Ω η^{'}$ interaction with $J^{P} = 3/ 2^{-}$ , they are all repulsive. After an investigation on the femtoscopic correlation functions, we find that, due to the spin-averaging effect, the overall $Ω ϕ$ correlation function exhibits a weak dependence on the source size, which provides a crucial significance of our model for future experimental examinations in relativistic heavy-ion collisions.
↳ hep-phhep-exhep-latnucl-thPRC(2026)·3 citations
07
Binary neutron star mergers with SPHINCS_BSSN: temperature-dependent equations of state and damping of constraint violations
Bhaskar Biswas🇩🇪 · Stephan Rosswog🇩🇪 · Peter Diener🇺🇸 · Lukas Schnabel🇩🇪
Neutron star mergers hold the key to several grand challenges of contemporary (astro-)physics. In view of the upcoming next generation of ground-based detectors, it is crucial to keep improving theoretical predictions to harvest the full scientific returns from these investments. We introduce here a substantial update of our Lagrangian numerical relativity code SPHINCS_BSSN. Apart from changing our unit system, we add constraint damping terms to the BSSN spacetime evolution equations. We demonstrate that this measure reduces, without noteworthy computational cost, the Hamiltonian constraint violations by more than an order of magnitude. We further implement contributions to thermal energy and pressure that are based on Fermi liquid theory and contain a parametrization of the Dirac effective mass. These terms can be combined with any cold equation of state, and they enhance the physical realism of our simulations and introduce a physics-based concept of a temperature. In a set of merger simulations, we demonstrate good agreement with other temperature-dependent numerical relativity simulations. We find that different parametrizations of the Dirac effective mass can translate into shifts of $\sim 150$ Hz in the dominant post-merger gravitational wave peak frequency.
↳ astro-ph.HEgr-qcnucl-th6 citations
08
Gaussian fluctuating Generally covariant diffusion
David Montenegro🇧🇷 · Giorgio Torrieri🇧🇷
We extend the previously developed [1] generally covariant formalism to include diffusion of conserved charges, and comment on the seming difference between the chemica potential term and the diffusion term
↳ hep-thgr-qchep-phnucl-thPRD(2026)·2 citations
09
Entanglement Viscosity: from Unitarity to Irreversibility in Accelerated Frames
G. Yu. Prokhorov🇷🇺
We demonstrate that the unitarity of quantum field theory, through the positivity of spectral functions, underlies thermodynamic irreversibility for a subsystem separated by a horizon, in direct analogy with the irreversibility of renormalization-group flows. To this end, we explicitly find the shear and bulk viscosities -- the entanglement viscosities -- for thermal radiation in Rindler space using the universal spectral representation. A direct consequence of the obtained general formulas is the relationship between the acceleration-induced shear viscosity in flat space and the conformal quantum anomaly in curved space, pointing to a possible novel probe of the conformal anomaly in systems with extreme acceleration. Moreover, for conformal field theories, we explicitly show that globally entanglement viscosity saturates the Kovtun-Son-Starinets bound.
↳ hep-thhep-phnucl-thPRD(2026)·4 citations
10
Anti-collinear resummation in JIMWLK evolution in the linear regime
Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱 · Maxim Nefedov🇮🇱 · Vladimir Skokov🇺🇸
The recently-proposed resummation procedure for anti-collinear logarithms in the JIMWLK kernel~\cite{Kovner:2023vsy} is studied in the linear (BFKL) regime in the fixed-coupling approximation. Simple closed form expressions for the resummed momentum space kernel and characteristic function $χ (n, γ)$ are found. We find that the anti-collinear pole in the leading order characteristic function at $γ = 1$ disappears, and instead $χ (γ = 1) = \frac{12}{11} \frac{π}{α _{s} N _{c}}$ for $n_{F} = 0$ . Comparison with the known NLO BFKL eigenvalue, with the target-Bjorken limit ( $Q_{T} ≫ Q_{P}$ ) of the $γ^{*} (Q_{P}) + γ^{*} (Q_{T})$ -scattering amplitude and with the ``all-poles'' resummation prescription are presented.
↳ hep-phhep-thnucl-thJHEP(2026)·1 citation
11
Resolution of the hyperfine puzzle and its significance for two fermion Dirac atoms
Gordon Baym · Glennys Farrar
The hyperfine interaction in the ground state of a hydrogen atom of assumed radius $R$ is proportional to $- 1/ R^{3}$ , raising the question of why the hyperfine interaction does not lead to collapse of hydrogen, or positronium. We approach the problem in terms of a minimax variational calculation based on the exact Gordon solution of the Dirac equation for the hydrogen atom ground state. The full Dirac treatment leads to the result that in an assumed variational state of size $R$ , when $R$ minimizes the total energy the magnetic moment of the electron assumes its usual value, $e ℏ/2 m c$ , but when $R < ℏ/ m c$ , the effective electron magnetic moment becomes essentially $e R /2$ , softening the hyperfine interaction and eliminating an energy minumum at small $R$ . The magnetic moment of the proton is similarly suppressed, and the hyperfine interaction of a small size atom becomes bounded by the kinetic energy, thus assuring stability. We extend the Dirac variational calculation to positronium where we find simple results for the ground state energy and hyperfiine interaction, and then extend this variational calculation to Coulombic atoms of two fermions of arbitrary masses. This paper also lays out a framework for treating diquarks as relativistic Coulombic systems, in the presence of color electric and magnetic interactions.
↳ physics.atom-phhep-phnucl-thPRA(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE