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Nuclear Theory·nucl-th

Monday·December 16, 2024

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 06

    Quantum stresses in the hydrogen atom

    Adam Freese🇺🇸

    Gravitational form factors are often interpreted as providing access to stresses inside hadrons, in particular through Fourier transforms of the form factors and . Some researchers, however, have expressed skepticism of this interpretation. I revisit the question, and argue that it is indeed appropriate to interpret these quantities as stress distributions. I consider the hydrogen atom's ground state as a familiar example, and use the pilot wave interpretation of quantum mechanics to give the distributions a clear meaning. A striking result is that -- rather than -- quantifies the force law binding the system, which can be understood through Cauchy's first law of motion.

    ↳ hep-phnucl-thquant-phPRD(2025)·15 citations
  2. 07

    In-medium electromagnetic form factors of pseudoscalar mesons from the quark model

    Ahmad Jafar Arifi🇯🇵 · Parada T. P. Hutauruk🇰🇷 · Kazuo Tsushima🇧🇷

    We explore the modifications of hadron structure in a nuclear medium, focusing on the spacelike electromagnetic form factors (EMFFs) of light and heavy-light pseudoscalar mesons. By combining the light-front quark model (LFQM) with the quark-meson coupling (QMC) model, which reasonably reproduces EMFFs in free space and the saturation properties of nuclear matter, respectively, we systematically analyze the in-medium EMFFs and charge radii of mesons with various quark flavors. Our findings show that the EMFFs of charged (neutral) mesons exhibit a faster fall-off (increase) with increasing four-momentum transfer squared and nuclear density. Consequently, the absolute value of the charge radii of mesons increases with nuclear density, where the rate of increase depends on their quark flavor contents. We observe that the EMFFs of pions and kaons undergo significant modifications in the nuclear medium, while heavy-light mesons are only slightly modified. By decomposing the quark flavor contributions to EMFFs, we show that the medium effects primarily impact the light-quark sector, leaving the heavy-quark sector nearly unaffected. The results of this study further suggest the importance of the medium effects at the quark level.

    ↳ hep-phnucl-thPRD(2025)·8 citations
  3. 08

    Photon-induced neutron, proton and alpha evaporation from heavy nucleus

    P. Jucha · K. Mazurek · M. Klusek-Gawenda · M. Ciemala · A. Szczurek · Yuliia Shevchuk · S. Słotwiński

    In ultraperipheral heavy-ion collisions (UPCs) at the Large Hadron Collider (LHC) Pb nuclei are excited through interactions induced by strong electromagnetic fields. The expected excitation energy could reach hundreds MeV, which leads to the subsequent emission of various particles, including neutrons, protons, and alpha particles. To accurately describe deexcitation of nuclei, we have developed two novel approaches. The first method utilizes the Heavy Ion Phase Space Exploration (HIPSE) model to simulate pre-equilibrium emissions and to estimate the excitation energy of the remaining nucleus. Our second approach introduces a new technique for modeling the excitation energy of the nucleus. This method consists of a two-component function to represent the excitation energy distribution more precisely, accounting for the energy loss due to the interaction between photons and quasi-deuteron. Both of these modeling techniques are integrated with the results produced by the GEMINI++ generator, which implements the Hauser-Feshbach formalism to simulate the statistical decay of excited nuclei. The alternative calculations are done with EMPIRE platform. Using these approaches, we obtained the cross sections for the emission of neutrons, protons, and alpha particles resulting from UPC at the LHC. Our results were compared with the experimental data of the ALICE group on neutron and proton multiplicities.

    ↳ hep-phnucl-thActa Phys.Polon.Supp.(2025)·1 citation
  4. 09

    Equation of State Independent Determination on the Radius of a 1.4 Neutron Star Using Mass-Radius Measurements

    Chun Huang

    Traditional methods for determining the radius of a 1.4 neutron star () rely on specific equations of state (EOS) models that describe various types of dense nuclear matter. This dependence on EOS models can introduce substantial systematic uncertainties, which may exceed the measurement uncertainties when constraining . In this study, we explore a novel approach to constraining using data from NICER observations of PSR J0030+0451 (J0030) and PSR J0437-4715 (J0437). However, this work presents a more data-driven analysis framework, substantially decreasing the need for EOS assumptions. By analyzing the Mass-Radius measurements of these two neutron stars, we infer using statistical methods based mostly on observational data. We examine various hotspot configurations for J0030, along with new J0437 observations, and their effects on the inferred radius. Our results are consistent with X-ray timing, gravitational wave, and nuclear physics constraints, while avoiding EOS-related biases. The same method has also been applied to a simulated mass-radius dataset, based on our knowledge of future X-ray telescopes, demonstrating the model's ability to recover the injected value in certain cases. This method provides a data-driven pathway for extracting neutron star properties and offers a new approach for future observational efforts in neutron star astrophysics.

    ↳ astro-ph.HEastro-ph.SRnucl-thApJL(2025)·8 citations
  5. 10

    Toward a foundation model for heavy-ion collision experiments based on point-cloud diffusion

    Manjunath Omana Kuttan🇩🇪 · Kai Zhou🇩🇪 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪

    A novel point cloud diffusion model for relativistic heavy-ion collisions, capable of ultra-fast generation of complete, event-by-event collision output, is introduced. When trained on UrQMD cascade simulations, the model generates realistic collision event output containing 26 distinct hadron species, as a list of particle momentum vectors along with their particle ID. From solving inverse problems to accelerating model calculations or detector simulations, the model can be a promising general purpose tool for heavy-ion collisions beneficial to both theoretical studies and experimental applications.

    ↳ hep-phhep-exnucl-exnucl-thPRC(2025)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE