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Nuclear Theory·nucl-th

Wednesday·July 15, 2026

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 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
  2. 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 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 Ra and Ra. A simplified analysis method based on the single-particle spectrum at the octupole deformation parameter is proposed to identify the key single-particle levels driving octupole deformation. It is found that the orbitals from and and the orbitals from and , 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
  3. 03

    Harmonic-dependent geometry-to-flow transfer in AMPT Ru+Ru and Zr+Zr isobar collisions

    Murad Badshah🇵🇰 · Muhammad Ajaz🇸🇦

    We present a fixed- study of geometry-to-flow transfer in string-melting AMPT simulations of and collisions at 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, , 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 pattern is maintained when varying the binning, peripheral-bin treatment, flow 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
  4. 04

    Thermal conductivity of dense 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 hyperons.

    nucl-thastro-ph.HEhep-ph0 citations
  5. 05

    Role of the pre-equilibrium particle emission in the No production in the Pb(Ca, xn)No reaction

    Yu.L. Parfenova · M.S. Tezekbayeva · I.A. Egorova · A.N. Ismailova

    Experimental data on the production of No in its ground and isomeric states in the Pb(Ca,2n)No reaction at 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 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 No. The proposed approach also reproduces the observed incident-energy dependence of the residual-nucleus production cross sections.

    nucl-th0 citations
  6. 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 -- which is canonically conjugate to the momentum fraction -- allows a spatial description of the longitudinal degree of freedom. We show how 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 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

Affiliations

first authorsco-authorsvia INSPIRE