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Nuclear Theory·nucl-th

Thursday·November 28, 2024

15 papers—5 primary·10 cross-listed

All15Primary5Cross-lists10
  1. 01

    Neutron emission from the photon-induced reactions in ultraperipheral ultrarelativistic heavy-ion collisions

    Pawel Jucha🇵🇱 · Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱 · Michal Ciemala🇵🇱 · Katarzyna Mazurek🇵🇱

    The ultraperipheral collisions are the source of various interesting phenomena based on photon-induced reactions. We calculate cross sections for single and any number of n, p, , -rays in ultraperipheral heavy-ion collision for LHC energies. We analyze the production of a given number of neutrons relevant for a recent ALICE experiment, for = 5.02~TeV. In our approach, we include both single and multiple photon exchanges as well as the fact that not all photon energies are used in the process of equilibration of the residual nucleus. We propose a simple two-component model in which only part of photon energy is changed into the excitation energy of the nucleus () and compare its results with outcomes of HIPSE and EMPIRE codes. The role of high photon energies for small neutron multiplicities is discussed. Emission of a small number of neutrons at high photon energies seems to be crucial to understand the new ALICE data. All effects work in the desired direction, but the description of the cross section of four- and five-neutron emission cross sections from first principles is rather demanding. The estimated emission of charged particles such as protons, deuterons and is shortly discussed and confronted with very recent ALICE data, obtained with the proton Zero Degree Calorimeter.

    nucl-thhep-phPRC(2025)·6 citations
  2. 02

    Impact of tensor forces on quasifission product yield distributions

    Liang Li · Lu Guo · K. Godbey · A. S. Umar

    We employ the microscopic time-dependent Hartree-Fock (TDHF) theory to study the 48Ca+249Bk and 48Ti+238U systems, taking into account the dependence on orientation for deformed nuclei and full range of impact parameters. By analyzing fragment distributions of neutron and proton numbers, we assess the influence of different isoscalar and isovector tensor coupling constants of the effective nucleon-nucleon interaction. The quasifission yield distributions of 48Ca + 249Bk collision system utilizing SLy5t and T31 parametrizations exhibit more pronounced spherical shell effects compared to those using SLy5, T44 and T62 sets. Furthermore, within each parametrization group, the distributions for SLy5t and T31 are closely aligned, as are those for SLy5, T44, and T62. Similarly, the yield distributions for the 48Ti + 238U system using SLy5t and T31 also reflect the more pronounced spherical shell effects relative to SLy5 and T62, while the charge distribution shows much better agreement with experimental results for the SLy5t and T62 parametrizations compared to SLy5 and T31. The yield distributions for the 48Ca+249Bk and 48Ti+238U systems, when compared across the SLy5, SLy5t, T31, T44, and T62 parametrizations, indicate that the influence of tensor forces on quasifission fragments is reflected in the prominence of shell effects. This influence appears to be sensitive only in specific regions within the isoscalar and isovector coupling constant parameter space. In the 48Ti + 238U system, the prominence of shell effects is manifested not only through shifts in peak positions but also through narrower yield distributions.

    nucl-thPRC(2024)·8 citations
  3. 03

    Exploring the nuclear momentum anisotropy based on intermediate-energy heavy-ion collisions

    Xiao-Hua Fan · Zu-Xing Yang · Peng-Hui Chen · Zhi-Pan Li · Wei Zuo · Masaaki Kimura · Shunji Nishimura

    We simulate ultra-central collisions of prolate uranium-uranium nuclei at intermediate energies using the isospin-dependent Boltzmann-Uehling-Uhlenbeck model to investigate the impact of momentum anisotropy on spatial geometric effects. By defining the quadrupole deformation parameter in momentum space , we establish an ellipsoidal Fermi surface, aligning its rotational symmetry axis with the one in coordinate space. It is found that oblate momentum density enhances elliptic flow , while prolate momentum density has the opposite effect, particularly pronounced in the outer, high transverse momentum region. Momentum anisotropy also causes differences in the initial momentum mean projection along the beam direction, with larger projections producing more pion mesons. Additionally, significant effects on mean square elliptic flow are observed in non-polarized collisions. We further examine the relationship between the - slope and , eliminating systematic errors through the two-system ratio. These findings provide important references for experimentalists in heavy-ion collisions and valuable feedback to theorists regarding nuclear structure.

    nucl-thPLB(2025)·0 citations
  4. 04

    High density symmetry energy: A key to the solution of the hyperon puzzle

    Jun-Ting Ye🇨🇳 · Rui Wang🇮🇹 · Si-Pei Wang🇨🇳 · Lie-Wen Chen🇨🇳

    The recently developed nuclear effective interaction based on the so-called N3LO Skyrme pseudopotential is extended to include the hyperon-nucleon and hyperon-hyperon interactions by assuming the similar density, momentum, and isospin dependence as for the nucleon-nucleon interaction. The parameters in these interactions are determined from either experimental information if any or chiral effective field theory or lattice QCD calculations of the hyperon potentials in nuclear matter around nuclear saturation density . We find that varying the high density behavior of the symmetry energy can significantly change the critical density for hyperon appearance in the neutron stars and thus the maximum mass of static hyperon stars. In particular, a symmetry energy which is soft around but stiff above about , can lead to for hyperon stars and simultaneously be compatible with (1) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities obtained from flow data in heavy-ion collisions; (2) the microscopic calculations of the equation of state for pure neutron matter; (3) the star tidal deformability extracted from gravitational wave signal GW170817; (4) the mass-radius relations of PSR J0030+0451, PSR J0740+6620 and PSR J0437-4715 measured from NICER; (5) the observation of the unusually low mass and small radius in the central compact object of HESS J1731-347. Furthermore, the sound speed squared of the hyperon star matter naturally displays a strong peak structure around baryon density of , consistent with the model-independent analysis on the multimessenger data. Our results suggest that the high density symmetry energy could be a key to the solution of the hyperon puzzle in neutron star physics.

    nucl-thastro-ph.HEhep-phnucl-exApJ(2025)·24 citations
  5. 05

    Iterative solutions of the ATDHFB equations to determine the nuclear collective inertia

    Xuwei Sun · Jacek Dobaczewski · Markus Kortelainen · David Muir · Jhilam Sadhukhan · Adrian Sánchez-Fernández · Herlik Wibowo

    An iterative adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) method is developed within the framework of Skyrme density functional theory. The ATDHFB equation is solved iteratively to avoid explicitly calculating the stability matrix. The contribution of the time-odd mean fields to the ATDHF(B) moment of inertia is incorporated self-consistently, and the results are verified by comparing them with the dynamical cranking predictions. The inertia mass tensor is calculated with the density-derivative term evaluated by numerical differentiation.

    nucl-thActa Phys.Polon.Supp.(2025)·1 citation

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first authorsco-authorsvia INSPIRE