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Nuclear Theory·nucl-th

Thursday·April 30, 2026

12 papers—5 primary·7 cross-listed

All12Primary5Cross-lists7
  1. 01

    Possible explanation of Hoehler's clustering: effective partial-wave mixing induced by truncation

    A. Svarc🇭🇷

    Hoehler noted that resonance poles obtained from different partial waves in scattering appear to bunch together near a small set of common complex energies, and suggested that this could indicate mixing between angular momenta. Here, we examine whether at least part of this pattern could arise effectively from the extraction procedure itself. Exact partial-wave unitarity preserves the separation of angular momenta in the infinite problem, whereas practical pole extraction from bilinear observables requires truncation of the partial-wave series. Combined with the truncation-induced mixing mechanism established in Ref.~\cite{Svarc2026}, this provides a natural source by which fitted partial-wave coefficients can inherit overlapping pole-bearing content, thereby offering a plausible contribution to Hoehler-type clustering.

    nucl-th0 citations
  2. 02

    Thermal and geometric normal modes of spectral fluctuations in heavy-ion collisions

    Rupam Samanta🇵🇱

    The transverse momentum spectrum of charged particles in ultra-relativistic heavy-ion collisions fluctuates event-by-event, encoding signatures of underlying collective dynamics. Such fluctuations originate from a combined effect of thermal and geometric fluctuations in the initial state. We present a direct decomposition of these spectral fluctuations through principal component analysis performed on the joint covariance structure of normalized spectrum, mean transverse momentum and elliptic flow squared. The first two leading modes explain 99.5\% of the total variance, and are orthogonally rotated by imposing physical constraints motivated by the initial state thermal and geometric response. The resulting thermal and geometric modes bear direct analogy with the vibrational normal modes of a linear triatomic molecule. The thermal mode entirely drives the experimentally measured , while the geometric mode contributes substantially to in non-central collisions, providing a transparent explanation of its characteristic low- sign change. The study establishes the first physically motivated interpretation of principal component modes in the field of heavy-ion collisions and provides an experimental window into the thermo-geometric structure of the QGP initial state.

    nucl-thhep-phnucl-exPLB(2026)·1 citation
  3. 03

    Effectiveness of nonflow suppression using multi-particle correlators

    Chong Ye🇨🇳 · Wei-Liang Qian🇨🇳 · Yue Cui🇧🇷 · Dan Wen🇨🇳 · Yutao Xing🇧🇷 · Rui-Hong Yue🇨🇳 · Takeshi Kodama🇧🇷

    As flow estimators, multi-particle correlators, particularly the higher-order ones, are generally regarded as effective tools for suppressing non-flow contributions. In this work, however, using two well-known toy models that simulate non-flow effects, we demonstrate that multi-particle correlators can, especially in small systems, yield estimates that deviate even further from the underlying flow harmonics than those obtained from other conventional approaches. The two toy models considered here are designed to mimic non-flow effects arising from particle decay and global momentum conservation, such that the {\it apparent} harmonic coefficients become significantly different from the {\it input} values. We provide an analytic explanation for the observed behavior of flow estimates based on multi-particle correlators. Specifically, in the toy model mimicking particle decay, we elucidate the oscillations observed in and . For the other toy model simulating momentum conservation, we show that multi-particle cumulants introduce a deformation in the collective flow that is unique to multi-particle correlators. Additionally, we compare these results with those obtained using the maximum-likelihood estimation method, a recently proposed flow estimator that serves as a viable alternative to traditional techniques.

    nucl-th0 citations
  4. 04

    Neutron Stars and Neutron Skins: Connecting Finite Nuclei to Dense Matter

    C.A. Bertulani

    This is a brief overview of the connection between neutron skin thickness in finite nuclei and the equation of state of neutron-rich matter, with applications to neutron stars. Multiple experimental probes are discussed, including dipole polarizability, parity-violating electron scattering, heavy-ion fragmentation, quasi-free scattering, and ultraperipheral collisions. A consistent picture emerges from Bayesian analyses combining experimental data and energy density functionals, providing constraints on the symmetry energy and its slope.

    nucl-thastro-ph.HEastro-ph.SR0 citations
  5. 05

    Outer-crust equations of state for neutron stars

    P.S. Koliogiannis · N. Paar

    The equation of state of the outer crust of neutron stars is sensitive to nuclear mass predictions and provides a direct connection to the properties of nuclei throughout the nuclide map, including those beyond experimental reach. We quantify the impact of contemporary nuclear mass models on the composition and thermodynamic properties of the outer crust and assess the consequences for crust-dominated neutron-star configurations near the minimum-mass limit. We constructed four outer-crust equations of state based on the relativistic energy density functional and machine-learning mass model tables. The equilibrium composition of cold catalysed matter in -equilibrium was obtained by minimising the Gibbs free energy per nucleon, and the resulting equations of state were implemented in neutron-star structure calculations. The different mass inputs lead to variations in the equilibrium nuclide sequence, distinct last bound nuclei, and moderate shifts in the neutron-drip density. In contrast, the associated thermodynamic properties, as well as the minimum-mass neutron-star configurations, remain closely aligned across the four outer-crust equations of state. The model dependence of the outer crust is primarily reflected in the detailed nuclide composition and in the precise location of neutron drip. Nevertheless, the considered outer-crust equations of state yield closely consistent predictions for the relevant neutron-star observables, providing a reliable input for stellar modelling.

    nucl-thastro-ph.HEastro-ph.SR0 citations

Affiliations

first authorsco-authorsvia INSPIRE