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Journal of Physics G: Nuclear and Particle Physics - latest papers

Latest articles for Journal of Physics G: Nuclear and Particle Physics

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  • Correlation between nuclear shape and ISGMR properties in even–even 90 ...
    The ground-state deformations of even–even Zr nuclei were calculated using covariant energy density functionals with two different types of interactions: meson-exchange and point-coupling. The shape evolution of the considered nuclei, sudden onset of large deformations, and phenomena of shape coexistence were systematically analyzed. Furthermore, the isoscalar giant monopole resonance (ISGMR) has been built on both the ground state and the second shape configurations using the quasiparticle finite amplitude method . The response of the zirconium nuclei to isoscalar monopole excitation, depending on their shapes, has been discussed in detail. It has been found that the ISGMR strength function is strongly governed by nuclear deformation. Our calculation indicates that the ISGMR is significantly affected by both types of axial deformation and evolves into a fragmented structure. These measurable effects are presented in terms of the energies and strengths of the peaks arising in the giant monopole resonance (GMR). In the case of larger deformation, the ISGMR is found to exhibit a dual structure. To investigate the origin of the dual structure of the ISGMR, the strength of the K = 0 branch of the ISGQR has also been calculated, and its connection with the ISGMR has been discussed. In addition to deformation, the effect of neutron excess on the GMR has also been examined, and it has been found to contribute to the low-energy region and considerably enhance its strength.

  • Finite-density dynamics of chemically equilibrating QGP in conformal Gubser flow and hard thermal photon production
    We study the chemical equilibration of a hot and dense quark–gluon plasma (QGP) at finite baryon density produced in relativistic heavy-ion collisions within conformal Gubser flow. Chemical non-equilibrium is incorporated through fugacity parameters in the parton phase-space distribution functions, whose evolution is governed by master rate equations coupled to the hydrodynamic expansion with transverse flow. We analyze the interplay between chemical equilibration and finite-density dynamics, and investigate its impact on hard thermal photon production. We observe that both finite density and transverse expansion delay chemical equilibration, leading to a chemically undersaturated medium with quarks lagging behind gluons. While the overall thermal photon yield from the expanding system is suppressed in the non-equilibrium scenario, we find an enhanced early-time contribution to high photon production. By analyzing the instantaneous photon emission in the presence of chemical non-equilibrium, we demonstrate that the rates exhibit a distinct temporal structure arising from the interplay of rapid cooling and evolving fugacities. These features may provide potential observable signatures of chemical equilibration dynamics in the QGP.

  • One neutron triaxial halo candidates in aluminum isotopes from reaction observables
    Microscopic description of one neutron ( ) halo candidates Al, with particular triaxial shape, is presented by combining the triaxial relativistic Hartree–Bogoliubov theory in continuum with the Glauber reaction model for the first time. In this scheme, the reaction cross sections of aluminum isotopes on a carbon target at 240 and 900 MeV A are calculated, which exhibit a pronounced increase for Al + C deviating from the systematic trend of their neighbors. Furthermore, the predicted longitudinal momentum distributions of the residues after removal reactions for Al + C are narrower than those for Al + C, which suggest halo structure with spatially extended density distribution. Based on the large occupation probabilities of -wave valence neutrons, we identify Al as the first triaxially deformed -wave halo candidates. This work cast a new light on the search for the heavier halo nuclei for future experiments in the mass region of , through theoretical predictions from triaxial structure to reaction observables.

  • Study of unbound excited states in 50,52Ar and the shell closures at N = 32 and ...
    Neutron-unbound states in Ar and Ar were investigated via the (p,2p) proton-knockout reaction using the invariant-mass spectroscopy technique. Two ( Ar) and three ( Ar) distinct, narrow resonances were observed in the vicinity of the neutron separation energy. Based on a comparison with theoretical level schemes and calculated (p,2p) cross sections, tentative spin-parity assignments have been proposed. The good degree of consistency between the predicted level structures and the observed states indicates that the large = 32 and = 34 shell gaps inherent in the theoretical calculations accurately describe the nuclear structure in this region. These results provide further support for the robustness of these subshell closures in the neutron-rich argon isotopes.

  • A generalized false vacuum Skyrme model
    We propose a generalization of the False Vacuum Skyrme model for any simple compact Lie group . Now the Skyrme field is a map , while the remaining fields correspond to the entries of a symmetric, positive, and invertible -dimensional matrix . We prove that the global minima correspond to the fields being self-dual solutions of the generalized BPS Skyrme model, together with a particular field configuration for the Skyrme field that leads to a spherically symmetric topological charge density. As in the case of the original model, the minimization of the energy leads to the so-called Coleman’s reduced problem, defined in the context of false vacuum decay. This imposes a condition on the Skyrme field, which, if satisfied, makes the total energy of the global minima, as well as the main properties of the model, equivalent to those obtained for the case. We study this condition and its consequences within the generalized rational map ansatz and show how it can be satisfied for , where and are positive integers, with the Hermitian symmetric spaces being . We also provide a numerical study of the baryon density, root-mean-square radius, and binding energy that deepens previously analysis for the False Vacuum Skyrme model. Additionally, in the case of , we have studied the application of our model to the description of the binding energies and masses of the -hypernuclei.