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Nuclear Theory·nucl-th

Wednesday·June 26, 2024

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Hybrid isentropic twin stars

    Juan Pablo Carlomagno · Gustavo A. Contrera · Ana Gabriela Grunfeld · David Blaschke

    We present a study of hybrid neutron stars with color superconducting quark matter cores at finite temperature that results in sequences of stars with constant entropy per baryon, . For the quark matter equation of state, we employ a recently developed nonlocal chiral quark model while nuclear matter is described with a relativistic density functional model of the DD2 class. The phase transition is obtained by a Maxwell construction under isothermal conditions. We find that traversing the mixed phase on a trajectory at low in the phase diagram shows a heating effect while at larger the temperature drops. This behavior may be attributed to the presence of a color superconducting quark matter phase at low temperatures and the melting of the diquark condensate which restores the normal quark matter phase at higher temperatures. While the isentropic hybrid star branch at low is connected to the neutron star branch, it gets disconnected at higher entropy per baryon so that the "thermal twin" phenomenon is observed. We find that the transition from connected to disconnected hybrid star sequences may be estimated with the Seidov criterion for the difference in energy densities. The radii and masses at the onset of deconfinement exhibit a linear relationship and thus define a critical compactness of the isentropic star configuration for which the transition occurs which for large enough is accompanied by an instability. The results of this study may be of relevance for uncovering the conditions for the supernova explodability of massive blue supergiant stars by the quark deconfinement mechanism. The accretion-induced deconfinement transition with thermal twin formation may contribute to explaining the origin of eccentric orbits in some binary systems and the origin of isolated millisecond pulsars.

    nucl-thastro-ph.HEUniverse(2024)·11 citations
  3. 03

    Transient spin modes from relaxational axial kinetic theory

    Shu Lin🇨🇳 · Haiqin Tang🇨🇳

    We study the dynamics of spin mode by solving the axial kinetic equations under the relaxation time approximation in the presence of dissipative sources. We find transient spin modes in response to electric field with spacetime inhomogeneity, fluid acceleration and shear. To the lowest order in spatial momentum , we find the responses to electric field and acceleration can be interpreted as retarded response to temporal variations of magnetic field and vorticity respectively. The response to shear occurs at and can be reduced to retarded response to spatial variation of vorticity. Beyond lowest order, the responses to all three sources are non-local with branch cut in the dispersions. We argue that the non-locality is a consequence of the quasi-particle picture underlying the kinetic description. We also analyze spin transport equation taking into account spin response to temporal and spatial variations of vorticity. We find the corrections turn the original first order spin transport equation into a third order one (or a second order one in the homogeneous limit). The change in order of transport equation is a consequence of non-local nature of the responses, suggesting possible breakdown of gradient expansion in spin hydrodynamics for microscopic theories with quasi-particles.

    nucl-thhep-phPRD(2024)·7 citations
  4. 04

    Towards Hypernuclei from Nuclear Lattice Effective Field Theory

    Fabian Hildenbrand🇩🇪 · Serdar Elhatisari🇹🇷 · Zhengxue Ren🇩🇪 · Ulf-G. Meißner🇩🇪

    Understanding the strong interactions within baryonic systems beyond the up and down quark sector is pivotal for a comprehensive description of nuclear forces. This study explores the interactions involving hyperons, particularly the particle, within the framework of nuclear lattice effective field theory (NLEFT). By incorporating hyperons into the NLEFT framework, we extend our investigation into the sector, allowing us to probe the third dimension of the nuclear chart. We calculate the separation energies () of hypernuclei up to the medium-mass region, providing valuable insights into hyperon-nucleon () and hyperon-nucleon-nucleon () interactions. Our calculations employ high-fidelity chiral interactions at NLO for nucleons and extend it to hyperons with leading-order S-wave interactions as well as forces constrained only by the systems. Our results contribute to a deeper understanding of the SU(3) symmetry breaking and establish a foundation for future improvements in hypernuclear calculations.

    nucl-thhep-lathep-phphysics.comp-phEPJA(2024)·32 citations
  5. 05

    Study of Heavy Quarkonia in the presence of magnetic field by Nikiforov Uvarov method

    Rishabh Sharma🇮🇳 · Siddhartha Solanki🇮🇳 · Manohar Lal🇮🇳 · Vineet Kumar Agotiya🇮🇳

    The N-dimensional radial Schrodinger equation has been solved using the Nikiforov Uvarov (NU) method, in which we used the medium modified form of Cornell potential and quasi-particle Debye mass with strong magnetic field background. The binding energies and the mass spectra of heavy quarkonium have been studied in the N-dimensional space for different values of magnetic field, the binding energy decreases with increasing magnetic field, which shows early dissociation of heavy quarkonium system. The influence of dimensionality number has also been discussed on binding energies of J/{\psi} and {\Upsilon} for fixed value of magnetic field. It is found that with an increase in dimensionality, the binding energy starts decreasing from a higher initial value. The results obtained are quite consistent with recent studies.

    ↳ hep-phnucl-thInt.J.Mod.Phys.A(2024)·3 citations
  6. 06

    The as a hadronic molecule

    Ju-Jun Xie🇨🇳 · Li-Sheng Geng🇨🇳

    Recently, a new excited baryon state, , was observed in the invariant mass spectra of and by the Belle Collaboration. This state has a narrow width ( MeV) compared to other baryon states with a similar mass. In this paper, we provide a mini-review on the state from the molecular perspective, where it appears to be a dynamically generated state with spin-parity from the coupled-channels interactions of the and in -wave and in -wave. Additionally, alternative explanations for the resonance are also discussed.

    ↳ hep-phnucl-thChin.Phys.Lett.(2024)·11 citations
  7. 07

    MC-EKRT: Monte Carlo event generator with saturated minijet production for initializing 3+1 D fluid dynamics in high energy nuclear collisions

    Mikko Kuha · Jussi Auvinen · Kari J. Eskola · Henry Hirvonen · Yuuka Kanakubo · Harri Niemi

    We present a novel Monte-Carlo implementation of the EKRT model, MC-EKRT, for computing partonic initial states in high-energy nuclear collisions. Our new MC-EKRT event generator is based on collinearly factorized, dynamically fluctuating pQCD minijet production, supplemented with a saturation conjecture that controls the low- particle production. Previously, the EKRT model has been very successful in describing low- observables at mid-rapidity in heavy-ion collisions at the LHC and RHIC energies. As novel features, our new MC implementation gives a full 3-dimensional initial state event-by-event, includes dynamical minijet-multiplicity fluctuations in the saturation and particle production, introduces a new type of spatially dependent nuclear parton distribution functions, and accounts for the conservation of energy/momentum and valence-quark number. In this proof-of-principle study, we average a large set of event-by-event MC-EKRT initial conditions and compute the rapidity and centrality dependence of the charged hadron multiplicities and elliptic flow for the LHC Pb+Pb and RHIC Au+Au collisions using 3+1 D viscous fluid-dynamical evolution. Also event-by-event fluctuations and decorrelations of initial eccentricities are studied. The good agreement with the rapidity-dependent data suggests that the same saturation mechanism that has been very successful in explaining the mid-rapidity observables, works well also at larger rapidities.

    ↳ hep-phnucl-thPRC(2025)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE