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Nuclear Theory·nucl-th

Friday·February 14, 2025

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 01

    Causality constraints on radiative transfer

    Lorenzo Gavassino🇺🇸

    The standard formula, due to Spiegel, for the smoothing of temperature fluctuations by radiative transfer is unstable in relativity. This is due to the fact that Spiegel neglected the transit time of light, thereby allowing the transport coefficients to move outside the convex geometry compatible with causality (the "hydrohedron"). Here, we fix this pathology. First, we prove that the linearized radiative transfer equations are causal and covariantly stable by construction. Then, we repeat Spiegel's calculation accounting for the finite speed of photons. We find that the full transfer problem can be solved analytically. All the infinite (exact) transport coefficients arising from it fall inside the hydrohedron. Our analysis also accounts for isotropic scattering.

    nucl-thastro-ph.HEhep-thPRD(2025)·4 citations
  2. 02

    Bose-Einstein condensation of five clusters in Ne and supersolidity

    S. Ohkubo · J. Takahashi · Y. Yamanaka

    We show that the five cluster states recently observed in Ne, slightly above the five threshold energy, are Bose-Einstein condensates of five clusters. The states are described well using a superfluid cluster model, where the order parameter is defined. We suggest that the the five states are fragmented. Theory predicts the emergence of a five rotational roton band characterized by a large moment of inertia. This band is formed through roton excitations of the five BEC vacuum and possesses dual properties of superfluidity and crystallinity, a property of supersolidity. The persistent existence of such a roton bandis discussed and confirmed for the four condensate above the four threshold in O and the three condensate above the three threshold in C.

    nucl-thcond-mat.quant-gasnucl-exEur.Phys.J.Plus(2025)·1 citation
  3. 03

    Quarkonium Spectroscopy in the Quark-Gluon Plasma

    Zhanduo Tang🇺🇸 · Biaogang Wu🇺🇸 · Andrew Hanlon🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Ralf Rapp🇺🇸

    The properties of bound states are fundamental to hadronic spectroscopy and play a central role in the transition from hadronic matter to a quark-gluon plasma (QGP). In a strongly coupled QGP (sQGP), the interplay of temperature, binding energy and large collisional widths of the partons poses formidable challenges in evaluating the in-medium properties of hadronic states and their eventual melting. In particular, the existence of heavy quarkonia in the QGP is a long-standing problem that is hard to solve by considering their spectral properties on the real-energy axis. We address this problem by analyzing in-medium thermodynamic quarkonium -matrices in the complex energy plane. We first validate this method in vacuum, where the -matrix poles of observed states are readily identified. When deploying this approach to recent self-consistently calculated -matrices in the QGP, we find that poles in the complex energy plane can persist to surprisingly large temperatures, depending on the strength of the in-medium interactions. While the masses and widths of the pole positions are precisely defined, the notion of a binding energy is not due to the absence of thresholds caused by the (large) widths of the underlying anti-/quark spectral functions. Our method thus provides a new and definitive quantum-mechanical criterion to determine the melting temperature of hadronic states in the sQGP while increasing the accuracy in the theoretical determination of transport parameters.

    nucl-thPRL(2025)·13 citations
  4. 04

    Low-energy spectra of nobelium isotopes: Skyrme random-phase-approximation analysis

    V. O. Nesterenko · M. A. Mardyban · A. Repko · R. V. Jolos · P.-G. Reinhard · Alan A. Dzhioev

    Low-energy spectra in the isotopic chain No are systematically investigated within the fully self-consistent Quasiparticle Random-Phase-Approximation (QRPA) using Skyrme forces SLy4, SLy6, SkM* and SVbas. QRPA states of multipolarity =20, 22, 30, 31, 32, 33, 43, 44 and 98 are considered. The main attention is paid to isotopes No and No where the most extensive experimental spectroscopic information is available. In these two nuclei, a reasonable description of and isomers is obtained with forces SLy4 and SLy6. The disputed isomer in No is assigned as neutron two-quasiparticle configuration . The isomers are additionally analyzed using Skyrme functionals UNEDF1, UNEDF2 and UNEDF1. At the energies 1.2 - 1.4 MeV, the 2qp -isomers in No and in No are also predicted. In No, the isomer should be accompanied by the nearby counterpart. It is shown that, in the chain No, some features of No and No should exhibit essential irregularities caused by a noticeable shell gap in the neutron single-particle spectrum and corresponding reduction of the neutron pairing. In particular, low-energy pairing-vibrational states in No are predicted.

    nucl-thPRC(2025)·2 citations
  5. 05

    Source function from two-particle correlation function through entropy-regularized Richardson-Lucy deblurring

    C. K. Tam · Z. Chajęcki · P. Danielewicz · P. Nzabahimana

    Source functions are obtained from - and -- correlation functions by applying the Richardson-Lucy (RL) deblurring to the Koonin-Pratt (KP) equation. To prevent fitting of noise in the correlation function, total-variation (TV) regularization is employed that has been effective in ordinary image restoration. TV alone cannot ensure normalization of the source functions. To ensure the latter, we propose a maximum-entropy regularized RL algorithm (MEM-RL). We outline the MEM-RL formalism and optimization strategy for the KP equation, demonstrating its effectiveness on both simulated and experimental data, including the - and - correlation functions.

    nucl-thPRC(2025)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE