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Nuclear Theory·nucl-th

Wednesday·December 4, 2019

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    Alpha Decay to Doubly Magic Core in Quartetting Wave Function Approach

    Shuo Yang🇨🇳 · Chang Xu🇨🇳 · Gerd Roepke🇩🇪 · Peter Schuck🇫🇷 · Zhongzhou Ren🇨🇳 · Yasuro Funaki🇯🇵 · Hisashi Horiuchi🇯🇵 · Akihiro Tohsaki🇯🇵 · Taiichi Yamada🇯🇵 · Bo Zhou🇯🇵

    We present a microscopic calculation of -cluster formation in heavy nuclei Te (+Sn), Po (+Pb) and their neighbors Sn, Te, Pb and Po by using the quartetting wave function approach. Improving the local density approximation, the shell structure of the core nucleus is considered, and the center-of-mass (c.o.m.) effective potential for the quartet is obtained self-consistently from the shell model wavefunctions. The -cluster formation and decay probabilities are obtained by solving the bound-state of the c.o.m. motion of the quartet and the scattering state of the formed -cluster in the Gurvitz approach. Striking shell effects on the -cluster formation probabilities are analyzed for magic numbers 50, 82 and 126. The computed -decay half-lives of these special nuclei are compared with the newest experimental data.

    nucl-thPRC(2020)·47 citations
  2. 02

    Wigner Function for Spin-1/2 Fermions in Electromagnetic Fields

    Xin-Li Sheng🇩🇪

    We study the Wigner function for massive spin-1/2 fermions in electromagnetic fields. Dirac form kinetic equation and Klein-Gordon form kinetic equation are obtained for the Wigner function, which are derived from the Dirac equation. The Wigner function and its kinetic equations are expanded in terms of the generators of Clifford algebra and a complicated system of partial differential equations is obtained. We prove that some component equations are automattically satisfied if the rest ones are fulfilled. In this thesis two methods are proposed for calculating the Wigner function, which are proved to be equivalent. The Wigner function is analytically calculated following the standard second-quantization procedure in the following cases: free fermions with or without spin imbalance, in constant magnetic field, in constant electric field, and in constant parallel electromagnetic field. Strong-field effects, such as the Landau levels and Schwinger pair-production are reproduced using the Wigner function approach. For an arbitrary space-time dependent field configuration, a semi-classical expansion with respect to the reduced Planck's constant is performed. We derive general expressions for the Wigner function components at linear order in , in which order the spin corrections start playing a role. A generalized Bargmann-Michel-Telegdi (BMT) equation and a generalized Boltzmann equation are obtained for the undetermined polarization density and net fermion number density, which can be used to construct spin-hydrodynamics in the future. We also make a comparison between analytical results and the ones from semi-classical expansion, which shows coincidence for weak electromagnetic fields and small spin imbalance.

    nucl-thhep-th11 citations
  3. 03

    Photon spectra and anisotropic flow in heavy ion collisions at the top RHIC energy within the integrated hydrokinetic model with photon hadronization emission

    V. Yu. Naboka🇺🇦 · Yu. M. Sinyukov🇺🇦 · G. M. Zinovjev🇺🇦

    The integrated HydroKinetic Model (iHKM) is applied to analyse the results of direct photon spectra as well as elliptic and triangular flow measurements in 200A GeV Au+Au collisions at RHIC for different centrality bins. Experiments detect the strong centrality dependence of photon elliptic and triangular flow as increasing -coefficients towards peripheral collisions. The photon production in the model is accumulated from the different sources along with the process of relativistic heavy ion collision developing. Those include the primary hard photons from the parton collisions at the very early stage of the process, the photons generated at the pre-thermal phase of dense matter evolution, then thermal photons at partially equilibrated hydrodynamic quark-gluon stage, together with radiation displaying a confinement and, finally, from the hadron gas phase. Along the way a hadronic medium evolution is treated in two distinct, in a sense opposite, approaches: chemically equilibrium and chemically non-equilibrium, namely, chemically frozen expansion. We find the description of direct photon spectra, elliptic and triangular flow are significantly improved, similar to that found in iHKM for the LHC energies, if an additional portion of photon radiation associated with the confinement processes, the "hadronization photons", is included into consideration.

    nucl-thNPA(2020)·7 citations
  4. 04

    Probing the equation of state of neutron star matter with gravitational waves from binary inspirals in light of GW170817: a brief review

    Andreas Guerra Chaves🇳🇱 · Tanja Hinderer🇳🇱

    Neutron stars are unique testbeds for exploring the physics of strongly interacting matter in extreme regimes of density, temperature, and isospin that are not accessible anywhere else in the universe. The nature of neutron star matter can now be probed with gravitational-waves (GWs) from binary driven by nonlinear gravity, where phenomena such as tidal effects lead to characteristic matter-dependent GW signatures. We focus here on the dominant tidal GW imprints that were most relevant for the event GW170817. We review the role of the tidal deformability parameter, its definition, computation, and relation to the equation of state. We briefly discuss the implications of GW170817, representing the first-ever constraints on tidal deformability from GW data. Finally, we outline opportunities and challenges for probing subatomic physics with GWs, as the measurements will become more precise and will probe a diversity of the binary neutron star population in the coming years.

    nucl-thastro-ph.HEJ.Phys.G(2019)·68 citations
  5. 05

    Effects of oscillating spacetime metric background on a complex scalar field and formation of topological vortices

    Shreyansh S. Dave🇮🇳 · Sanatan Digal🇮🇳

    We study the time evolution of a complex scalar field in the symmetry broken phase in the presence of oscillating spacetime metric background. In our (2+1)-dimensional simulations, we show that the spacetime oscillations can excite an initial field configuration, which ultimately leads to the formation of topological vortices in the system. At late times, field configuration achieves a disordered state. A detailed study of the momentum and frequency modes of the field reveals that these field excitations are driven by the phenomenon of parametric resonance. In extremely high frequency regime where frequency of spacetime oscillations is much larger than the field-mass, the formed vortices are not topological in nature. Interestingly in this regime, for a suitable choice of parameters of the simulation, we observe a persistent lattice structure of vortex-antivortex pairs. We discuss applications of our study to the dynamics of interior superfluidity of neutron stars during binary neutron star mergers, in generation of excitation in ultralight axion-like field near a strong gravitational wave source, etc.

    ↳ hep-thastro-ph.HEcond-mat.quant-gashep-ph+1PRD(2021)·5 citations
  6. 06

    Crystallization of the inner crust of a neutron star and the influence of shell effects

    T. Carreau🇫🇷 · F. Gulminelli🇫🇷 · N. Chamel🇧🇪 · A. F. Fantina🇫🇷 · J. M. Pearson🇨🇦

    Context. In the cooling process of a non-accreting neutron star, the composition and properties of the crust are thought to be fixed at the finite temperature where nuclear reactions fall out of equilibrium. A lower estimation for this temperature is given by the crystallization temperature, which can be as high as K in the inner crust, potentially leading to sizeable differences with respect to the simplifying cold-catalyzed matter hypothesis. Aims. We extend the recent work by Fantina et al. (2019) on the outer crust, to the study of the crystallization of the inner crust and the associated composition in the one-component plasma approximation. Methods. The finite temperature variational equations for non-uniform matter in both the liquid and the solid phases are solved using a compressible liquid-drop approach with parameters optimized on four different microscopic models which cover the present uncertainties in nuclear modeling. Results. We consider separately the effect of the different nuclear ingredients with their associated uncertainties, namely the nuclear equation of state, the surface properties in the presence of a uniform gas of dripped neutrons, and the proton shell effects arising from the ion single-particle structure. Our results suggest that the highest source of model dependence comes from the smooth part of the nuclear functional. Conclusions. We show that shell effects play an important role at the lowest densities close to the outer crust, but the most important physical ingredient to be settled for a quantitative prediction of the inner crust properties is the surface tension at extreme isospin values.

    ↳ astro-ph.HEnucl-thAstron.Astrophys.(2020)·52 citations
  7. 07

    Investigation of particle distributions in Xe-Xe collision at 5.44 TeV with Tsallis statistics

    Hai-Fu Zhao🇨🇳 · Bao-Chun Li🇨🇳 · Hong-Wei Dong🇨🇳

    The distribution characteristic of final-state particles is one of significant parts in high energy nuclear collisions. The transverse momentum distribution of charged particles carries essential evolution information about the collision system. Tsallis statistics is used to investigate the transverse momentum distribution of charged particles produced in Xe-Xe collisions at 5.44 TeV. On the basis, we reproduce the nuclear modification factor of the charged particles. The calculated results agree approximately with the experimental data measured by the ALICE Collaboration.

    ↳ hep-phnucl-thAdv.High Energy Phys.(2020)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE