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Nuclear Theory·nucl-th

Friday·July 17, 2020

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 05

    Hybrid stars from a three-flavor NJL model with two kinds of tensor condensates

    M. Morimoto🇯🇵 · Y. Tsue🇯🇵 · J. da Providencia🇵🇹 · C. Providencia🇵🇹 · M. Yamamura🇯🇵

    To obtain the equation of state of quark matter and construct hybrid stars, we calculate the thermodynamic potential in the three-flavor Nambu-Jona-Lasinio model including the tensor-type four-point interaction and the Kobayashi-Maskawa-'t Hooft interaction. To construct the hybrid stars, it is necessary to impose the beta-equilibrium and charge neutrality conditions on the system. It is shown that tensor condensed phases appear at large chemical potential. Under the possibility of the existence of the tensor condensates, the relationship between the radius and mass of hybrid stars is estimated.

    ↳ hep-phnucl-thIJMPE(2020)·2 citations
  2. 06

    Exact equilibrium distributions in statistical quantum field theory with rotation and acceleration: scalar field

    F. Becattini🇮🇹 · M. Buzzegoli🇮🇹 · A. Palermo (University of Florence and INFN)🇮🇹

    We derive a general exact form of the phase space distribution function and the thermal expectation values of local operators for the free quantum scalar field at equilibrium with rotation and acceleration in flat space-time without solving field equations in curvilinear coordinates. After factorizing the density operator with group theoretical methods, we obtain the exact form of the phase space distribution function as a formal series in thermal vorticity through an iterative method and we calculate thermal expectation values by means of analytic continuation techniques. We separately discuss the cases of pure rotation and pure acceleration and derive analytic results for the stress-energy tensor of the massless field. The expressions found agree with the exact analytic solutions obtained by solving the field equation in suitable curvilinear coordinates for the two cases at stake and already - or implicitly - known in literature. In order to extract finite values for the pure acceleration case we introduce the concept of analytic distillation of a complex function. For the massless field, the obtained expressions of the currents are polynomials in the acceleration/temperature ratios which vanish at , in full accordance with the Unruh effect.

    ↳ hep-thcond-mat.stat-mechgr-qcmath-ph+2JHEP(2021)·52 citations
  3. 07

    Production of Light Nuclei in Heavy Ion Collisions via Hagedorn Resonances

    Kai Gallmeister🇩🇪 · Carsten Greiner (Goethe University, Frankfurt am Main)🇩🇪

    The physical processes behind the production of light nuclei in heavy ion collisions are unclear. The nice theoretical description of experimental yields by thermal models conflicts with the very small binding energies of the observed states, being fragile in such a hot and dense environment. Other available ideas are delayed production via coalescence, or a cooling of the system after the chemical freeze-out according a Saha equation, or a `quench' instead of a thermal freeze-out. A recently derived prescription of an (interacting) Hagedorn gas is applied to consolidate the above pictures. The tabulation of decay rates of Hagedorn states into light nuclei allows to calculate yields usually unaccessable due to very poor Monte Carlo statistics. Decay yields of stable hadrons and light nuclei are calculated. While the scale-free decays of Hagedorn states alone are not compatible with the experimental data, a thermalized hadron and Hagedorn state gas is able to describe the experimental data. Applying a cooling of the system according a Saha-equation with conservation of nucleons and anti-nucleons in number leads to (nearly) temperature independent yields, thus a production of the light nuclei at temperatures much lower than the chemical freeze-out temperature is possible.

    ↳ hep-phnucl-thEPJA(2021)·6 citations
  4. 08

    Field of a moving locked charge in classical electrodynamics

    Alexander J. Silenko🇨🇳

    The paradox of a field of a moving locked charge (confined in a closed space) is considered and solved with the use of the integral Maxwell equations. While known formulas obtained for instantaneous fields of charges moving along straight and curved lines are fully correct, measurable quantities are average electric and magnetic fields of locked charges. It is shown that the average electric field of locked charges does not depend on their motion. The average electric field of protons moving in nuclei coincides with that of protons being at rest and having the same spatial distribution of the charge density. The electric field of a twisted electron is equivalent to the field of a centroid with immobile charges which spatial distribution is defined by the wave function of the twisted electron.

    ↳ physics.class-phhep-phnucl-thMod.Phys.Lett.A(2020)·1 citation
  5. 09

    GW190814 as a massive rapidly-rotating neutron star with exotic degrees of freedom

    V. Dexheimer🇺🇸 · R.O. Gomes🇩🇪 · T. Klähn🇺🇸 · S. Han🇺🇸 · M. Salinas🇺🇸

    In the context of the massive secondary object recently observed in the compact-star merger GW190814, we investigate the possibility of producing massive neutron stars from a few different equation of state models that contain exotic degrees of freedom, such as hyperons and quarks. Our work shows that state-of-the-art relativistic mean field models can generate massive stars reaching , while being in good agreement with gravitational-wave events and x-ray pulsar observations, when quark vector interactions and non-standard self-vector interactions are introduced. In particular, we present a new version of the Chiral Mean Field (CMF) model in which a different quark-deconfinement potential allows for stable stars with a pure quark core. When rapid rotation is considered, our models generate stellar masses that approach, and in some cases surpass . We find that in such cases fast rotation does not necessarily suppress exotic degrees of freedom due to changes in stellar central density, but require a larger amount of baryons than what is allowed in the non-rotating stars. This is not the case for pure quark stars, which can easily reach and still possess approximately the same amount of baryons as stable non-rotating stars. We also briefly discuss possible origins for fast rotating stars with a large amount of baryons and their stability, showing how the event GW190814 can be associated with a star containing quarks as one of its progenitors.

    ↳ astro-ph.HEastro-ph.SRnucl-thPRC(2021)·176 citations

Affiliations

first authorsco-authorsvia INSPIRE