Nuclear Theory·nucl-th

Wednesday·July 15, 2026

10 papers—6 primary·4 cross-listed

01
Analytical penetration probability including the centrifugal potential: An improved Buck--Merchant--Perez model for alpha-decay half-lives
Minghui Hu · Pengfei Ma · Kai Ren · Junlong Tian · Cheng Li
We derive a closed-form, non-perturbative WKB penetration formula for alpha-decay that explicitly incorporates the centrifugal potential within the Buck--Merchant--Perez (BMP) cluster model. The centrifugal term is shown to enhance the hindrance by effectively enlarging the barrier width: it pushes the outer turning point outward and, via the Bohr--Sommerfeld quantization condition, shifts the inner turning point inward. Building on this analytical result, we further develop an improved BMP model in which the nuclear potential depth is expressed as a unified four-parameter formula that simultaneously encodes shell corrections, odd-even pairing effects, and orbital-angular-momentum dependence. For 534 ground-state-to-ground-state alpha decays spanning Z = 60--118, the root-mean-square deviation of log base 10 T1/2 is reduced to 0.267, representing a 57% improvement over the original constant-depth BMP model (0.615), with robust performance for both favored (0.188) and unfavored (0.398) transitions. The framework is further applied to predict the half-lives of hitherto-unmeasured nuclei in the region Z = 117--120, providing quantitative benchmarks for future experimental investigations.
nucl-th0 citations
02
Octupole deformation in even-even Ra isotopes from covariant density functional theory with localized exchange terms in a three-dimensional lattice space
Z. Y. Dong · Z. X. Ren · Q. Zhao · Z. M. Niu
The covariant density functional theory in a three-dimensional lattice space is extended to the PCF-PK1 functional with localized exchange terms and is employed to study the nuclear shape evolution of even-even Ra isotopes. Well-developed axial octupole deformations are found for the ground states of $^{222 - 228}$ Ra with no evidence of triaxial shapes. The energy gain of octupole deformation is employed to assess the stability of octupole deformation, with relatively larger values observed for $^{224}$ Ra and $^{226}$ Ra. A simplified analysis method based on the single-particle spectrum at the octupole deformation parameter $β_{3} = 0$ is proposed to identify the key single-particle levels driving octupole deformation. It is found that the $m_{z} = 3/2$ orbitals from $ν 1 j_{15/2}$ and $ν 2 g_{9/2}$ and the $m_{z} = 1/2$ orbitals from $π 1 i_{13/2}$ and $π 2 f_{7/2}$ , play crucial roles in the formation of octupole deformation in Ra isotopes. Furthermore, increasing the tensor coupling strength promotes octupole deformation, whereas reducing the pairing strength stabilizes it. Our results provide a microscopic understanding of octupole deformation in the Ra isotopic chain and highlight the importance of both tensor coupling and pairing correlations in reflection-asymmetric nuclear shapes.
nucl-th0 citations
03
Harmonic-dependent geometry-to-flow transfer in AMPT Ru+Ru and Zr+Zr isobar collisions
Murad Badshah🇵🇰 · Muhammad Ajaz🇸🇦
We present a fixed- $N_{part}$ study of geometry-to-flow transfer in string-melting AMPT simulations of $^{96} Ru +^{96} Ru$ and $^{96} Zr +^{96} Zr$ collisions at $s_{N N} = 200$ GeV. Four nuclear configurations are considered: deformation-only Ru+Ru, deformation-only Zr+Zr, deformation plus neutron skin Ru+Ru and deformation plus neutron skin Zr+Zr. The AMPT/HIJING initialization is modified to include deformed Woods--Saxon densities and, when enabled, separate proton and neutron Woods--Saxon radii and diffuseness parameters (neutron skin effect). We introduce an eccentricity-normalized isobar response double ratio, $D_{n} = (v_{n}^{Ru} / v_{n}^{Zr}) / (ε_{n}^{Ru} / ε_{n}^{Zr})$ , evaluated in common participant-number intervals. This observable eliminates the initial-geometry eccentricity ratio, and investigates whether the final-state flow ratio is fully determined by the initial-geometry ratio. We find that the elliptic double ratio is nearly unity, and the triangular double ratio is consistently greater than unity for the two deformation-only and deformation-plus-skin configurations. The positive $D_{3} - 1$ pattern is maintained when varying the $N_{part}$ binning, peripheral-bin treatment, flow $p_{T}$ range and rapidity/pseudorapidity acceptance. The result identifies a harmonic-dependent AMPT response: Ru/Zr elliptic flow follows leading eccentricity scaling to high accuracy, whereas triangular flow retains a residual response component after the triangularity ratio is divided out.
nucl-thhep-ph0 citations
04
Thermal conductivity of dense $n p Λ$ matter in neutron star cores
Tanay Choudhary🇮🇳 · Athira S. · Monika Sinha🇮🇳
The possible presence of hyperons in the cores of massive neutron stars has important implications for their microscopic transport properties and thermal evolution. Despite recent progress in modelling core transport, a dedicated analysis regarding the thermal conductivity of a specific $np\Lambda$ mixture remains absent from the existing literature. In this work, we investigate the thermal conductivity of dense, $\beta $-equilibrated $np\Lambda$ matter within the framework of the variational linearized Boltzmann kinetic approach, employing the density-dependent DDME2 equation of state across a baryon density range of $(0.5\text{--}4.5)\,n_0$. We find that neutrons still dominate thermal transport, while the onset of $\Lambda $ hyperons induces only a remarkably small reduction in neutron conductivity compared to pure nucleonic matter. These results suggests that the core thermal relaxation timescale remains practically unaltered in the presence of $Λ$ hyperons.
nucl-thastro-ph.HEhep-ph0 citations
05
Role of the pre-equilibrium particle emission in the $^{249 - 251}$ No production in the $^{204}$ Pb( $^{48}$ Ca, xn) $^{252 - x}$ No reaction
Yu.L. Parfenova · M.S. Tezekbayeva · I.A. Egorova · A.N. Ismailova
Experimental data on the production of $^{250}$ No in its ground and isomeric states in the $^{204}$ Pb( $^{48}$ Ca,2n) $^{250}$ No reaction at $^{48}$ Ca beam energies from 200 to 240 MeV are analyzed within a unified approach combining the Hauser--Feshbach statistical model and the Griffin exciton model, assuming the emission of one pre-equilibrium particle. The influence of pre-equilibrium processes on the production cross sections of the $^{249 - 251}$ No isotopes is investigated. The inclusion of pre-equilibrium light-particle emission significantly improves the description of the measured production cross sections, particularly in the high-energy region, where differences of several orders of magnitude are obtained, and for the population of the ground and isomeric states of $^{250}$ No. The proposed approach also reproduces the observed incident-energy dependence of the residual-nucleus production cross sections.
nucl-th0 citations
06
Three-dimensional, boost-invariant formalism for systems of relativistically moving constituents
Adam J. Freese · Anne L. Lashbrook · Gerald A. Miller
Light front quantum mechanics in three dimensions can be used to construct boost-invariant wave functions for the internal structure of relativistic systems. The Miller-Brodsky variable $z ~$ -- which is canonically conjugate to the momentum fraction $x$ -- allows a spatial description of the longitudinal degree of freedom. We show how $z ~$ can be constructed as an operator and prove its boost invariance. A relativistic harmonic oscillator potential from Li, Maris, Zhao and Vary [Phys Lett B 758 (2016) 118] is used as an example of a two-body interaction that can be constructed using $z ~$ and for which closed-form analytic solutions can be found. We systematically explore the conditions in which the non-relativistic harmonic oscillator solutions are reproduced and the conditions in which relativistic corrections are significant. Harmonic oscillator states are commonly used as a basis for nuclear many-body calculations. The present effort may provide a basis for providing light-front wave functions of nuclei.
nucl-thhep-ph0 citations
07
Using $γ$ +jets to quantify medium-induced jet broadening in heavy-ion collisions
Ankita Budhraja🇳🇱 · Marco van Leeuwen🇳🇱 · Wouter Waalewijn🇳🇱
The structure of jets produced in high-energy nucleus-nucleus collisions carries information on parton energy loss and interaction in the quark-gluon plasma. This parton energy loss results in migration of jets in terms of transverse momentum, leading to a selection bias in inclusive jet measurements. Using the JEWEL event generator, we investigate a strategy to reduce selection bias and access medium-induced jet broadening, in an experimentally viable way. As a baseline, we first consider large-R $γ$ +jet events, with little selection bias, which show a clear signal of medium-induced broadening in the jet girth. However, large-R is experimentally inaccessible due to the large underlying event fluctuations in heavy-ion collisions, so we re-cluster a collection of small-radius ( $r_{sub}$ = 0.2) jets as a proxy for the large-radius (R = 1.2) jet, which we refer to as a trimmed jet. We quantify to what extent trimmed jets recover signals of jet broadening and investigate its dependence on the subjet cone size and the minimum transverse momentum. We study the internal structure of the subjets to expose the dependence of jet quenching on different subjet configurations, finding a strong narrowing of PbPb jets for the 1-subjet configurations, and a visible signature of medium-induced broadening for sub-leading subjets. The jet radial profile reveals that contributions from medium-induced broadening are distinct from radiation in pp collisions. These contributions are not easily recovered using our trimming procedure, but are substantially enhanced in single-subjet configurations when considering the profile \emph{beyond} the subjet radius. This provides guidance for future experimental studies of jet-medium interactions using $γ$ +jet in heavy-ion collisions.
↳ hep-phnucl-th0 citations
08
Entangling Power and Symmetries in the Quantum Rabi Model
Ian Low🇺🇸 · Jens Koch🇺🇸 · Sahel Ashhab🇯🇵
The quantum Rabi model is a standard effective Hamiltonian in studies of light-matter interaction, capturing the simplest nontrivial setting in which a qubit couples to a single harmonic oscillator. Within the broader Rabi family, we focus on two special cases: the Jaynes-Cummings (JC) model, which carries an explicit $U (1)$ symmetry, and the asymmetric quantum Rabi model (AQRM), which possesses a parameter-dependent "hidden'' symmetry that appears only at integer bias, $ε / ω \in Z$ , and is not manifest in the Hamiltonian. We use the time-averaged entangling power as an operator-level diagnostic of these symmetry structures. Since the oscillator Hilbert space is infinite-dimensional, we compare two finite input ensembles: a Haar average after Fock-space truncation and a coherent-state average at fixed mean occupation $n ˉ$ . Both diagnostics show peaks at the integer-bias points of the AQRM, where the hidden symmetry resides. In contrast, the manifest $U (1)$ symmetry at the JC point instead gives a weak dip. Thus, the time-averaged entangling power responds to both the hidden symmetry and the $U (1)$ symmetry in the Rabi family, with the sign of the response indicating how the symmetry reorganizes the spectral expansion. These results demonstrate that the entangling power can serve as an operator diagnostic to reveal the presence and properties of hidden and manifest symmetries in light-matter systems.
↳ quant-phhep-phhep-thnucl-th2 citations
09
Two-fluid $f$ -mode oscillations of dark-matter-admixed neutron stars
Zi-Yue Zheng🇨🇳 · Ting-Ting Sun🇨🇳 · Huan Chen🇨🇳 · Xiao-Ping Zheng🇨🇳 · Jin-Biao Wei🇨🇳 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We study quadrupolar $f$ -mode oscillations of dark-matter-admixed neutron stars (DANSs) in full general relativity (GR). The ordinary component is described by microscopic Brueckner-Hartree-Fock matter matched to the Shen2020 crust, while the dark matter (DM) component is treated as a cold self-interacting fermion fluid coupled to ordinary matter only by gravity. For fixed-DM-fraction sequences we solve the polar two-fluid perturbation equations with an outgoing gravitational-wave (GW) boundary condition, obtaining complex eigenfrequencies rather than only real mode frequencies. The spectrum contains two principal $f$ -like sequences. Their local character can be ordinary-matter-led, DM-led, or mixed, and is diagnosed using the component kinetic energies, the displacement overlap, and the cancellation of the matter quadrupole. A main result is that, for intermediate DM fractions, one of the two-fluid branches can become weakly radiating, with damping times enhanced by several orders of magnitude. The same calculation gives the outgoing Zerilli amplitude and the GW damping time, which we use to estimate the GW energy required to reach a prescribed detector threshold. Thus the analysis extends previous two-fluid Cowling studies by retaining metric perturbations and the radiative boundary condition.
↳ gr-qchep-phnucl-th0 citations
10
Hadronic vacuum polarization contribution to $a_{μ}$ from functional methods with strong and electromagnetic isospin breaking
Angel S. Miramontes🇪🇸 · Adnan Bashir🇪🇸 · Christian S. Fischer🇩🇪 · Pablo Roig🇲🇽
We present a continuum-QCD determination of the leading-order hadronic vacuum-polarization contribution to the anomalous magnetic moment of the muon within the Dyson-Schwinger and Bethe-Salpeter equation framework. The calculation incorporates pion back-reaction, a fully dressed quark-photon vertex with a dynamically generated $ρ$ -resonance structure in the timelike region, and both strong and electromagnetic isospin breaking treated self-consistently at the quark level. We obtain $a_{μ}^{HVP, LO} (u + d + s + c) ∣_{ISB} = 709.7 \times 1 0^{- 10}$ , in good agreement with recent lattice-QCD determinations, and find an isospin-breaking shift of $Δ a_{μ}^{HVP, LO} = 4.5 \times 1 0^{- 10}$ ( $0.6%$ ), demonstrating that isospin-breaking effects, while quantitatively modest, are not negligible. Including the bottom-quark contribution and an indicative estimate of the systematic uncertainties, we obtain our final result, $a_{μ}^{HVP, LO} (u + d + s + c + b) ∣_{ISB} = (710.0 \pm 14.5) \times 1 0^{- 10}$ .
↳ hep-phhep-latnucl-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE