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Nuclear Theory·nucl-th

Monday·June 10, 2024

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    Barrier distribution extraction via Gaussian process regression

    Kyle Godbey

    This work presents a novel method for extracting potential barrier distributions from experimental fusion cross sections. We utilize a simple Gaussian process regression (GPR) framework to model the observed cross sections as a function of energy for three nuclear systems. The GPR approach offers a flexible way to represent the experimental data, accommodating potentially complex behavior without introducing strong prior assumptions. This method is applied directly to experimental data and is compared to the traditional direct extraction technique. We discuss the advantages of GPR-based barrier distribution extraction, including the capability to quantify uncertainties and robustness to noise in the experimental data.

    nucl-th1 citation
  2. 02

    Nonspherical Pauli-forbidden states in deformed halo nuclei: Impact on the resonant states in the particle rotor model

    Shin Watanabe · Antonio M. Moro

    Background: An important aspect of reducing nuclear many-body problems to few-body models is the presence of Pauli forbidden (PF) states, which are excluded in fully antisymmetrized calculations. Insufficient treatments of PF states in deformed halo nuclei underscore the need for model refinement. Purpose: We propose a new method utilizing Nilsson states as PF states in the orthogonality condition model, and investigate the impact of PF states on the properties of resonant states. Method: We investigate the scattering states of within the Particle Rotor Model (PRM) framework based on a deformed core and two-body model. We compare several methods for eliminating PF states and test them with the experimental data. Results: Our model successfully reproduces the experimental excitation function for elastic scattering cross section by properly eliminating PF states. The same calculation predicts the presence of a low-energy bump in the inelastic scattering excitation function, although its position is overestimated by about 1 MeV compared to experimental data. Conclusion: This study extends the applicability of the PRM, offering a comprehensive approach for exploring structures and reactions of loosely bound nuclei like B. Future integration with the continuum discretized coupled channels (CDCC) method promises to further advance the research.

    nucl-thPRC(2024)·4 citations
  3. 03

    Proton 3D reconstruction with T-odd TMD gluon densities

    Alessandro Bacchetta🇮🇹 · Francesco Giovanni Celiberto🇪🇸 · Marco Radici🇮🇹

    We present studies aimed at probing the 3D gluon content of the proton through spin-dependent TMD gluon densities, computed by means of the spectator-model approach. Our formalism incorporates a fit-based modulation function for the spectator mass, designed to capture longitudinal-momentum effects across a broad kinematic range. Special emphasis is placed on the time-reversal even Boer-Mulders and the time-reversal odd Sivers functions. Accurate understanding of these functions is crucial for conducting precise 3D analyses of nucleons, highlighting the importance of collaborative efforts between the LHC and EIC Communities.

    ↳ hep-phhep-exnucl-exnucl-thPoS(2024)·8 citations
  4. 04

    Deconfinement and chiral phase transitions in quark matter with chiral imbalance

    Francisco X. Azeredo🇧🇷 · Dyana C. Duarte🇧🇷 · Ricardo L. S. Farias🇧🇷 · Gastão Krein🇧🇷 · Rudnei O. Ramos🇧🇷

    We study the thermodynamics of the Polyakov-Nambu-Jona-Lasinio model considering the effects of an effective chiral chemical potential. We offer a new parametrization of the Polyakov-loop potential depending on temperature and the chiral chemical potential which, when used together with a proper regularization scheme of vacuum contributions, predicts results consistent with those from lattice simulations.

    ↳ hep-phhep-lathep-thnucl-thPRD(2024)·16 citations
  5. 05

    Shear viscosity from perturbative Quantum Chromodynamics to the hadron resonance gas at finite baryon, strangeness, and electric charge densities

    Isabella Danhoni🇩🇪 · Jordi Salinas San Martin🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

    Through model-to-data comparisons from heavy-ion collisions, it has been shown that the Quark Gluon Plasma has an extremely small shear viscosity at vanishing densities. At large baryon densities, significantly less is known about the nature of the shear viscosity from Quantum Chromodynamics (QCD). Within heavy-ion collisions, there are three conserved charges: baryon number (B), strangeness (S), and electric charge (Q). Here we calculate the shear viscosity in two limits using perturbative QCD and an excluded-volume hadron resonance gas at finite BSQ densities. We then develop a framework that interpolates between these two limits such that shear viscosity is possible to calculate across a wide range of finite BSQ densities. We find that the pQCD and hadron resonance gas calculations have different BSQ densities dependence such that a rather non-trivial shear viscosity appears at finite densities.

    ↳ hep-phnucl-thPRD(2025)·8 citations
  6. 06

    Wave functions of multiquark hadrons from representations of the symmetry groups

    Nicholas Miesch🇺🇸 · Edward Shuryak🇺🇸

    Construction of the wave functions of multiquark hadrons by traditional method based on tensor products of colors, flavors, spins (and orbital) parts becomes quite complex when quark numbers grow , as it gets difficult to satisfy requirements of Fermi statistics. Our novel approach is focused directly on representations of the permutation symmetry generators. After showing how is manifested in the wave functions of (excited) baryons, we use it to construct the wave functions for a set of pentaquarks and hexaquarks (n=5,6). We also have some partial results for larger systems, with and 12, and even beyond that as far as .

    ↳ hep-phnucl-thPRD(2024)·5 citations
  7. 07

    Unraveling Trace Anomaly of Supradense Matter via Neutron Star Compactness Scaling

    Bao-Jun Cai · Bao-An Li

    The trace anomaly quantifies the possibly broken conformal symmetry in supradense matter under pressure at energy density . Perturbative QCD (pQCD) predicts a vanishing at extremely high energy or baryon densities when the conformal symmetry is realized but its behavior at intermediate densities reachable in neutron stars (NSs) are still very uncertain. The extraction of from NS observations strongly depends on the employed model for nuclear Equation of State (EOS). Using the IPAD-TOV method based on an Intrinsic and Perturbatively Analysis of the Dimensionless (IPAD) Tolman-Oppenheimer-Volkoff (TOV) equations that are further verified numerically by using EOSs generated randomly with a meta-model in a very broad EOS parameter space constrained by terrestrial nuclear experiments and astrophysical observations, here we first show that the compactness of a NS with mass and radius scales very accurately with where is the ratio of pressure over energy density at NS centers. The scaling of NS compactness thus enables one to readily read off the central trace anomaly directly from the observational data of either the mass-radius or red-shift measurements. We then demonstrate indeed that the available NS data themselves from recent X-ray and gravitational wave observations can determine model-insensitively the trace anomaly as a function of energy density in NS cores, providing a stringent test of existing NS models and a clear guidance in a new direction for further understanding the nature and EOS of supradense matter.

    ↳ astro-ph.HEhep-phhep-thnucl-ex+1PRD(2025)·19 citations

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first authorsco-authorsvia INSPIRE