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Nuclear Theory·nucl-th

Monday·November 24, 2025

3 papers—1 primary·2 cross-listed

All3Primary1Cross-lists2
  1. 02

    Scatter-Limited Hybrid Monte Carlo, Deterministic Transport with Quasi-Monte Carlo Sampling

    Johannes Krotz🇺🇸 · Ryan G. McClarren🇺🇸

    We present a hybrid method for time-dependent particle transport that combines Monte Carlo (MC) estimation with a deterministic discrete ordinates (\(S_N\)) solve, augmented by quasi-Monte Carlo (QMC) sampling. For spatial discretizations, the MC component computes a piecewise-constant (cell-averaged) solution, while the \(S_N\) stage employs bilinear discontinuous finite elements. By hybridizing the formulation, the MC subproblem after a prescribed scatter limit becomes scattering-free, yielding a simple and efficient streaming/attenuation procedure. Between time steps, a simple scatter-free MC step is run to relabel the solution as an MC solution. A key feature of the approach is a tunable parameter \(N_{s}\) that controls how many material collisions are handled in the (Q)MC leg before handing off to the deterministic \(S_N\) solve; \(N_s=0\) recovers a purely uncollided MC leg, while \(N_s>0\) produces multi-scatter hybrids. QMC replaces pseudorandom draws with low-discrepancy points in the existing MC sampling maps, enabling a plug-in adoption within the standard MC code with modest, localized changes. We observe significant accuracy and convergence rate improvements through the use of QMC and practically no additional computational cost, which are generally not seen in comparable non-hybrid solves. We believe the multi-scatter approach provides additional flexibility in terms of parallelization and the choice of deterministic solver.

    ↳ math.NAcs.NAhep-thnucl-th0 citations
  2. 03

    Self-bound quark stars with a first-order two-to-three flavor phase transition

    G. Teruya🇧🇷 · G. Lugones🇧🇷 · A. G. Grunfeld🇦🇷

    We investigate self-bound quark stars in a flavor-dependent quark-mass density-dependent model with an excluded-volume correction. We chart the parameter space at zero pressure to identify self-bound regimes, including parametrizations in which self-bound two-flavor matter undergoes a genuine first-order transition at finite pressure. We construct cold, -equilibrated stellar sequences and compute the corresponding global properties (mass-radius relation, tidal deformability, and moment of inertia). For a wide region of the model parameter space, we find that the onset of a core occurs before the maximum-mass configuration is reached, yielding self-bound hybrid stars that follow the typical strange-quark-star sequence morphology but develop a characteristic kink at along the stellar curves. The excluded-volume parameter controls the stiffness of the equation of state and thus masses, radii, tidal deformabilities, and moments of inertia; intermediate repulsion typically reconciles with current astrophysical constraints. We further identify two equation-of-state-insensitive trends: dimensionless moment of inertia versus compactness and gravitational versus baryonic compactness. These results provide model-guided priors and tools for discriminating between hadronic and self-bound equations of state with multimessenger data.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thPRD(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE