Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>First-principle calculations based on the density functional theory (DFT) method are adopted to investigate the influence of a strong electric field on the <jats:sup>7</jats:sup>Be half-life. Accordingly, electronic structures of Be and BeO are examined in the presence of a homogeneous electric field. The electron density at the nucleus is estimated upon the geometry optimization. Our computations for the Be metal indicate a 0.02% increase in the decay rate of the <jats:sup>7</jats:sup>Be nucleus, corresponding to a 0.02% decrease in the <jats:sup>7</jats:sup>Be half-life, both at 5.14 V/Å (0.1 a.u.). Furthermore, it is determined that the decay rate of <jats:sup>7</jats:sup>Be is not considerably altered up to 3.6 V/Å in the BeO structure. Our results show that the screening energy of the electron can be dependent on the applied electric field strength. Furthermore, we predict variations in the Coulomb potential at the <jats:sup>7</jats:sup>Be nucleus due to electric field application. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Neutrons tunneling to the classically forbidden (CF) region in the neutron-rich nucleus <jats:inline-formula> <jats:tex-math><?CDATA $ ^{68} {\rm{Ca}}$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_7_074104_M1.jpg" xlink:type="simple" /> </jats:inline-formula> are investigated in the Skyrme Hartree-Fock (HF) and Hartree-Fock-Bogoliubov (HFB) models. The definition of the CF region is examined in the HF model by using different single-particle potentials for the bound states. In the HFB model, the weakly bound and continuum states could also contribute to the neutrons in the CF region due to the pairing correlation. Their asymptotic wave functions are carefully calculated by the Green’s function method. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The coexistence of neutron-neutron (<jats:italic>n</jats:italic>-<jats:italic>n</jats:italic>), proton-proton (<jats:italic>p</jats:italic>-<jats:italic>p</jats:italic>), and neutron-proton (<jats:italic>n</jats:italic>-<jats:italic>p</jats:italic>) pairings is investigated by adopting an effective density-dependent contact pairing potential. These three types of pairings can coexist only if the <jats:italic>n</jats:italic>-<jats:italic>p</jats:italic> pairing is stronger than the <jats:italic>n</jats:italic>-<jats:italic>n</jats:italic> and <jats:italic>p</jats:italic>-<jats:italic>p</jats:italic> pairings for the isospin asymmetric nuclear matter. In addition, the existence of <jats:italic>n</jats:italic>-<jats:italic>n</jats:italic> and <jats:italic>p</jats:italic>-<jats:italic>p</jats:italic> pairs might enhance <jats:italic>n</jats:italic>-<jats:italic>p</jats:italic> pairings in asymmetric nuclear matter when the <jats:italic>n</jats:italic>-<jats:italic>p</jats:italic> pairing strength is significantly stronger than the <jats:italic>n</jats:italic>-<jats:italic>n</jats:italic> and <jats:italic>p</jats:italic>-<jats:italic>p</jats:italic> ones. Conversely, the <jats:italic>n</jats:italic>-<jats:italic>p</jats:italic> pairing is reduced by the <jats:italic>n</jats:italic>-<jats:italic>n</jats:italic> and <jats:italic>p</jats:italic>-<jats:italic>p</jats:italic> pairs when the <jats:italic>n</jats:italic>-<jats:italic>p</jats:italic> pairing interaction approaches <jats:italic>n</jats:italic>-<jats:italic>n</jats:italic> and <jats:italic>p</jats:italic>-<jats:italic>p</jats:italic> pairings. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>We explore the effects of the density dependence of symmetry energy on the crust-core phase transition and dynamical instabilities in cold and warm neutron stars in the relativistic mean field (RMF) theory with point-coupling interactions using the Vlasov approach. The role of neutrino trapping is also considered. The crust-core transition density and pressure, distillation effect, and cluster size and growth rates are discussed. The present work shows that the slope of symmetry energy at saturation, temperature, and neutrino trapping have non-negligible effects.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>To explore the properties of neutron-rich nuclei with approximately 40 protons, the density-dependent point coupling (DD-PC1) effective interaction parameter is adopted in the relativistic mean-field theory with the complex momentum representation (RMF-CMR). The calculated two-neutron separation energy (<jats:italic>S</jats:italic> <jats:sub>2<jats:italic>n</jats:italic> </jats:sub>) and root-mean-square (rms) radii support the halo structure that appear in Mo and Ru isotopic chains. Besides, the neutron skin structures appear in Kr and Sr isotopes. The conclusions drawn are also supported by the single-particle energy levels and their occupancy probability and density distribution. Particularly, the energy levels, which reduce to bound states or are approximately 0 MeV with a small orbital angular momentum, are suggested to provide the primary contribution to increasing the neutron radius. Moreover, the single-particle energy levels significantly reflect the shell structure. In addition, the neutron drip line nuclei for Kr, Sr, Mo, and Ru elements are proposed via the changes in <jats:italic>S</jats:italic> <jats:sub>2<jats:italic>n</jats:italic> </jats:sub>. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>A nuclear mass formula based on the macroscopic microscopic approach is proposed, in which the number of model parameters is reduced compared with other macroscopic microscopic models. The root mean square (RMS) deviation with respect to 2314 training sets (measured nuclear masses) is reduced to 0.447 MeV, and the calculated value of each nucleus is no more than 0.8% different from the experimental value. The single and two nucleon separation energies and the shell gaps are calculated to test the model. The shell corrections and double magic number of superheavy nuclei are also analyzed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Three typical Pauli blocking algorithms in quantum molecular dynamics type models are investigated in the nuclear matter, the nucleus, and heavy ion collisions. In nuclear matter, the blocking ratios obtained with the three algorithms are underestimated by 13%-25% compared to the corresponding analytical values. For a finite nucleus, spurious collisions occur around the surface of the nucleus owing to the defects of the Pauli blocking algorithms. In the simulations of heavy ion collisions, the uncertainty of stopping power arising from the different Pauli blocking algorithms is less than 5%. Furthermore, the in-medium effects of nucleon-nucleon (<jats:italic>NN</jats:italic>) cross sections on the nuclear stopping power are discussed. Our results show that the transport model calculations with free <jats:italic>NN</jats:italic> cross sections result in the stopping power decreasing with beam energy when the beam energy is less than 300 MeV/u. To increase or decrease the values of the stopping power, the transport model calculations need enhanced or suppressed model dependent in-medium <jats:italic>NN</jats:italic> cross sections that are expected to be smaller than the true in-medium <jats:italic>NN</jats:italic> cross sections. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>The moments and moment products of conserved charges are believed to be sensitive to critical fluctuations, which have been adopted in determining the QCD critical point. Using a dynamical multiphase transport model, we reproduce the centrality and energy dependences of moments and moment products of net-charge multiplicity distributions in Au+Au collisions, measured by the Beam Energy Scan program at the RHIC. No non-monotonic energy dependence is observed. We infer that the moment products develop during the dynamical evolution of heavy-ion collisions. The observed difference based on the expectation of the Poisson baseline indicates a positive two-particle correlation between positively and negatively charged particles, which can arise from different dynamical processes at different stages. Therefore, to adopt moments and moment products of net-charge multiplicity distributions in determining the QCD critical point of relativistic heavy-ion collisions, it is essential to consider the dynamical evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a systematic determination of the responses of PandaX-II, a dual phase xenon time projection chamber detector, to low energy recoils. The electron recoil (ER) and nuclear recoil (NR) responses are calibrated, respectively, with injected tritiated methane or <jats:sup>220</jats:sup>Rn source, and with <jats:sup>241</jats:sup>Am-Be neutron source, in an energy range from 1-25 keV (ER) and 4-80 keV (NR), under the two drift fields, 400 and 317 V/cm. An empirical model is used to fit the light yield and charge yield for both types of recoils. The best fit models can describe the calibration data significantly. The systematic uncertainties of the fitted models are obtained via statistical comparison to the data. </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Considering a grand canonical ensemble, we study the phase structures and transitions of RN black holes surrounded by quintessence dark energy on two different boundary conditions, namely AdS space and a Dirichlet wall. For AdS space, under the condition of fixed temperature and potential, as the temperature increases for lower potential, the black hole undergoes a first-order phase transition, while for higher potential, no phase transition occurs. There are two different regions in the parameter space. For the Dirichlet wall, on which the temperature and potential are fixed, the state parameter of quintessence <jats:inline-formula> <jats:tex-math><?CDATA $ \omega=-2/3$?></jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpc_45_7_075101_M1.jpg" xlink:type="simple" /> </jats:inline-formula> is analyzed in detail. Then, three different physically allowed regions in the parameter space of the black hole are well studied. As the temperature rises, first-order and second-order phase transitions may occur. In this case, there are nine regions in the parameter space, which is evidently distinct from the case of AdS space. </jats:p>