Nuclear Theory·nucl-th

Friday·July 10, 2026

13 papers—8 primary·5 cross-listed

01
[Submitted on 8 Jul 2026]
Neutral pion momentum in hypertriton mesonic decay through a root-finding method
Emile Meoto🇨🇲
A root-finding method is used to study two-body mesonic decay in the hypertriton. We validate this Newton--Raphson root-finding approach by applying it to the negative-pion decay channel ( $_{Λ}^{3} H \to^{3} He + π^{-}$ ), for which the pion momentum and lambda binding energy were recently reported by MAMI A1 Collaboration as $p_{π^{-}} = 113.789 \pm 0.02 0_{stat.} \pm 0.11 2_{syst.} MeV / c$ and $B_{Λ} = 0.523 \pm 0.01 3_{stat.} \pm 0.07 5_{syst.}$ MeV, respectively. Using their reported $Λ$ binding energy, the root-finding method and an exact kinematic formula both yield $p_{π^{-}} = 113.790$ MeV/ $c$ , agreeing with each other. We then apply both the Newton--Raphson method and the exact formula to the neutral-pion decay channel ( $_{Λ}^{3} H \to^{3} H + π^{0}$ ), for which the neutral pion momentum cannot be directly measured due to difficulties in experimental setup. Both methods agree, yielding a predicted neutral-pion momentum of $p_{π^{0}} = 118.129$ MeV/ $c$ . This validates the root-finding algorithm as a robust equivalent for predicting pion momenta that may be experimentally inaccessible in some cases. Furthermore, it establishes the method as a reliable tool for extension to three-body mesonic decays, for which the pion momentum is a continuum and the exact kinematic formula can no longer be applied. In addition, the pion momentum computed allows for its 4-momentum to be completely determined, a useful input for investigating its two-photon decay ( $π^{0} \to γ γ$ ) in the rest frame of the hypertriton.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2607.07928 [pdf]
1 citation
02
[Submitted on 9 Jul 2026]
Full-Spectrum Quantum Simulation for the Nuclear Shell Model
B. Maheshwari🇮🇳 · P. Stevenson🇬🇧 · P. Van Isacker🇫🇷
The nuclear shell model is a general way of expressing the many-body nuclear Hamiltonian and deciphering the underlying nuclear structure. In today's era of modern and high-power computation, the primary limitation of the nuclear shell model is the enormous dimensionality of its Hilbert space, which far exceeds available storage capacity and prevents the diagonalization of the full Hamiltonian matrix in that space. Quantum computing offers a scalable solution to bypass this curse of dimensionality. In this work, we introduce a single-run quantum simulation capable of obtaining multiple shell-model eigenstates simultaneously. The nuclear Hamiltonian is transformed from a bit to a qubit basis using the Jordan-Wigner transformation, explicitly preserving fermionic anti-commutation. We employ a Subspace Search Variational Quantum Eigensolver (SSVQE) along with an Adaptive Derivative-Assembled Pseudo-Trotter (ADAPT) ansatz to construct the quantum circuit required to solve the shell-model problem. The ADAPT-SSVQE algorithm uses a symmetry-preserving single and double-excitation operator pool and optimizes a weighted energy sum to obtain the simultaneous convergence of all eigenstates within a targeted MJ subspace, eliminating the need for post-processing efforts to extract excited spectra. We benchmark this approach by solving the problem for two and three identical nucleons in a j = 9/2 orbital, successfully extracting five and ten mutually orthogonal states, respectively, within a 10-qubit active space. The algorithm achieves spectroscopic accuracy, in simulation, relative to exact diagonalization and intrinsically restores total angular momentum (\hat{J}^2) symmetry.
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph); Quantum Physics (quant-ph)
arXiv:
2607.08235 [pdf]
0 citations
03
[Submitted on 9 Jul 2026]
Relativistic Mean Field Approach with Chiral Symmetry Breaking and Quark Confinement in the light of Astrophysical Observations
Bikram Keshari Pradhan🇫🇷 · Mohamad Chamseddine🇫🇷 · Jérôme Margueron🇺🇸 · Hubert Hansen🇫🇷 · Guy Chanfray🇫🇷 · Jean-Paul Ebran🇫🇷 · Elias Khan🇫🇷
We perform a Bayesian analysis of a relativistic mean-field approach, which is an implementation of the chiral confining model with both chiral symmetry breaking and confinement effects, and which was recently proven to reproduce well the ground state properties of finite nuclei. We additionally explore the impact of couplings between $ρ$ and $ω$ mesons as well as a non-linear $ω$ coupling. Our models are simultaneously constrained by nuclear matter properties near saturation density, multi-messenger neutron star astrophysical observations, and/or lattice QCD predictions of the nucleon mass. It exhibits tension in simultaneously reproducing the $\sim 2 M_{⊙}$ massive NS and the tidal deformability inferred from GW170817. We show that an additional $ω ρ$ coupling, favored by Bayes factor analysis, substantially alleviates this tension, while adding a non-linear $ω$ self-interaction is not necessary for the RMF-CC model. Owing to the strong constraints on the scalar sector imposed by chiral dynamics and the softening of the equation of state at high densities induced by our treatment of confinement, the RMF-CC approach favors stiff equations of state. Since we do not consider phase transition in the core of neutron stars, this stiffening is obtained with large values of the incompressibility modulus of about $\sim 300$ MeV. We finally compare the well-known RMF model with RMF-CC models with the same constraints, and we obtain a preference for the RMF model in the absence of a phase transition in the core of neutron stars.
Comments:
24 page, 16 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2607.08412 [pdf]
0 citations
04
[Submitted on 9 Jul 2026]
Charge radii of calcium isotopes within relativistic configuration-interaction density functional theory
Teng Qu · Bo Li · Yakun Wang
The charge radii of calcium isotopes are investigated within the framework of relativistic configuration-interaction density functional (ReCD) theory. The ReCD theory microscopically incorporates beyond-mean-field correlations through rotational symmetry restoration and configuration mixing among quasiparticle excited states, and treats even-even and odd- $A$ isotopes on the same footing. It is found that beyond-mean-field correlations significantly soften the potential energy surfaces of calcium isotopes and shift the energy minima from nearly spherical mean-field solutions to deformed shapes. The quadrupole deformation parameters predicted by the ReCD theory show much better agreement with the available experimental data than the mean-field results, supporting the reliability of the calculated potential energy surfaces and highlighting the important role of beyond-mean-field correlations. Owing to the sensitive dependence of charge radii on nuclear deformation, the charge radii obtained within the ReCD framework are generally larger than the mean-field predictions. The nearly identical charge radii of $^{40} Ca$ and $^{48} Ca$ , as well as the unexpectedly large charge radius of $^{52} Ca$ , are well reproduced. Compared with the mean-field calculations, the description of the odd-even staggering is improved, especially for the enhanced charge radii of $^{42} Ca$ and $^{44} Ca$ . It is also worth noting that secondary local minima appear in the ReCD-based potential energy surfaces of the odd- $A$ calcium isotopes $^{41, 43, 47} Ca$ . The present results suggest that shape mixing between different local minima, which is not fully included in the present calculation, may further improve the description of the pronounced odd-even staggering observed in calcium isotopes.
Comments:
19 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2607.08478 [pdf]
0 citations
05
[Submitted on 9 Jul 2026]
Microscopic description of $^{12}$ C+ $^{12, 13}$ C fusion reactions at nuclear astrophysical energies
K. Nagao · K. Hagino · K. Uzawa
The $^{12}$ C + $^{12}$ C fusion reaction plays a key role in several astrophysical phenomena. However, it is difficult to determine its cross sections in the relevant energy region because of both low cross sections and strong resonant structures. On the other hand, the $^{12}$ C + $^{13}$ C system shows a much smoother energy dependence of fusion cross sections. To simultaneously analyze the $^{12}$ C + $^{12, 13}$ C systems, we here develop a reaction model that explicitly treats the entrance channel and the compound nucleus states. For this purpose, we combine the discrete basis model for the entrance channel and the shell model for the compound nuclei. The coupling strengths between the entrance channel and the compound nucleus states are determined so that the fusion cross sections for these systems match with each other at the resonance energies for the $^{12}$ C + $^{12}$ C system, as has been observed experimentally. The model successfully reproduces the significantly different behaviors of fusion cross sections in these systems.
Comments:
11 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2607.08502 [pdf]
0 citations
06
[Submitted on 9 Jul 2026]
A symmetry-based resolution of pseudo-gauge ambiguities in local equilibrium
Carlos Hoyos🇪🇸
The total angular momentum current can be decomposed into orbital and spin contributions in different ways, known as pseudo-gauges. This freedom leads to ambiguities in the definition of local-equilibrium density operators, which in turn affect estimates of spin polarization in heavy-ion collisions. In this work, the pseudo-gauge ambiguity, together with other ambiguities associated with improvements of conserved currents, is reformulated in terms of spurious symmetries corresponding to conserved currents with vanishing total charge. A prescription for the unambiguous definition of a local-equilibrium density operator is introduced using the currents associated with genuine symmetries. The resulting density operator is invariant under transformations that add improvement terms to local currents, including the energy-momentum tensor.
Comments:
5 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2607.08569 [pdf]
0 citations
07
[Submitted on 9 Jul 2026]
Lectures on lepton-nucleus quasielastic scattering with relativistic models
Raúl González-Jiménez🇪🇸
In these notes, basic concepts and necessary formulas for the modeling of elastic lepton-nucleon and quasielastic lepton-nucleus scattering using relativistic models are discussed. Certain theoretical developments are presented in meticulous detail, particularly those rarely found in papers or standard textbooks. In order to highlight the discrepancies between models and evaluate the impact of various nuclear effects, theoretical predictions are compared with inclusive electron scattering data. These notes are designed for Master's or PhD students embarking on their research in the field of neutrino-nucleus interactions at intermediate energies (ranging from several hundred MeV to a few GeV). They are intended to serve as a supplemental guide, never as a substitute for traditional textbooks on Scattering Theory and Quantum Field Theory. Currently, these notes are included in the course `Relativistic Quantum Theory: Nuclear Processes', which is integrated into both the Interuniversity Master in Nuclear Physics (https://master.us.es/fisicanuclear/index.php/) and the Erasmus Mundus Joint Master Degree in Nuclear Physics (https://www.emm-nucphys.eu/en), with the University of Seville as one of the partner institutions. Previously, this material was part of the course `Weak Interactions', within the same Master's programs.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex)
arXiv:
2607.08629 [pdf]
0 citations
08
[Submitted on 9 Jul 2026]
Secondary Hadron--Nucleus Collisions of Short-Lived Hadrons in Ultra-Relativistic Fixed-Target Heavy-Ion Interactions
Sanatan Digal · P. S. Saumia · Ajit M. Srivastava
Ultra-relativistic heavy nuclei traversing a solid target undergo successive nuclear encounters separated by atomic lattice spacings. At sufficiently high beam energies, Lorentz contraction reduces the proper time between collisions to $O (1 0^{4})$ ~fm $/ c$ in the center-of-mass frame of the first interaction. We then consider the fragmentation region of this first collision, and show that short-lived hadrons produced in this region, with additional Lorentz boost, can reach the next nucleus before decaying. We show that this geometry enables secondary hadron--nucleus collisions involving species that cannot be realized as conventional secondary beams or in subsequent hadron--nucleus interactions in cosmic-ray cascades. For a $2.76$ TeV-per-nucleon Pb beam incident on a solid Pb lattice, we determine which forward-produced hadrons can survive to a second interaction, estimate their collision probabilities, and analyze potential observable consequences. In particular, we identify some representative hadrons whose proper lifetimes are of order $1 0^{3}$ fm/c, e.g. specific mesons ( $η^{'}$ ) and heavy-flavor resonances ( $J / ψ, D^{*} (2010)$ ), as projectile species that become accessible through this collision space-time geometry. At substantially higher beam energies (for example, with 10 TeV per-nucleon Pb beam), the survival probabilities are significantly enhanced. This can make even very short lived hadrons with life times of few tens fm ( $Ξ (1530)$ , $ω (782)$ , $ϕ (1020)$ ) available for this secondary hadron-nucleus collision, providing an additional motivation for future ultra-relativistic fixed-target heavy-ion experiments.
Comments:
5 pages
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2607.08658 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE