We analyze the emission plateaus in the X-ray afterglow light curves of gamma-ray bursts （GRBs） and those in the optical light curves of type Ⅱ plateau su- pernovae （SNe Ⅱ-P） in order to study whether they have similar late energy injection behaviors. We show that correlations of bolometric energies （or luminosities） between the prompt explosions and the plateaus for the two phenomena are similar. The energy emitted by SNe II-P are at the lower end of the range of possible energies for GRBs. The bolometric energies （or luminosities） in the prompt phase Eexpl （or Lexpl） and in the plateau phase E_plateau （or L_plateau） share relations of E_expl ∝E _0.73±0.14_plateau and L_expl ∝ L^-0.70_plateau. These results may indicate a similar late energy injection behavior that produces the observed plateaus in these two phenomena.
We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.
ZHANG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3 1Department of Physics, Liaoning Normal University, Dalian 116029, China
In a unified algebraic scheme,we investigate the relation between the E(5) symmetry and the interacting boson model beyond the mean-field level.The results indicate that the E(5) symmetry is actually in between the critical point of the U(5)-O(6) transition and the O(6) limit but it is fairly close to the former based on the phase diagram of the interacting boson model at the large boson number limit.In addition,an algebraic Hamiltonian of the E(5)-β2n model is proposed.
The different timing results of the magnetar Swift J1822.3—1606 are analyzed and understood theoretically.It is noted that different timing solutions are caused not only by timing noise,but also because the period derivative is decreasing after the outburst.Both the decreasing period derivative and the large timing noise may originate from wind braking associated with the magnetar.Future timing of Swift J1822.3—1606 will help clarify whether or not its period derivative is decreasing with time.
It is still a matter of debate to understand the equation of state of cold matter with supra-nuclear density in compact stars because of unknown non-perturbative strong interaction between quarks. Nevertheless, it is speculated from an astrophysical view point that quark clusters could form in cold quark matter due to strong coupling at realistic baryon densities. Although it is hard to calculate this conjectured matter from first principles, one can expect that the inter-cluster interaction will share some general features with the nucleon- nucleon interaction successfully depicted by various models. We adopt a two-Gaussian component soft-core potential with these general features and show that quark clusters can form stable simple cubic crystal structure if we assume that the wave function of quark clusters have a Gaussian form. With this parametrization, the Tolman-Oppenheimer-Volkoff equation is solved with reasonably constrained parameter space to give massradius relations of crystalline solid quark stars. With baryon number densities truncated at 2n0 at surface and the range of the interaction fixed at 2 fm we can reproduce similar mass-radius relations to that obtained with bag model equations of state. The maximum mass ranges from - 0.5M⊙ to 〉 ～ 3M⊙. The recently measured high pulsar mass （〉～ 2M⊙） is then used to constrain the parameters of this simple interaction potential.
The origin of the shallow decay segment in γ-ray bursts' (GRB) early light curves remains a mystery, especially those cases with a long-lived plateau followed by an abrupt falloff. In this paper, we propose to understand the origins of the long-lived plateau by considering the solidification of newborn quark stars with latent heat released as energy injection to the GRB afterglow, and we suggest that an abrupt falloff would naturally appear after the plateau due to the energy injection cutoff. We estimated the total latent heat released during the phase transition of quark stars from liquid to solid states to be on the order of ～ 1051 ergs, which is comparable to the emission energy in the shallow decay segment. We also estimated the time scale of radiating the latent heat through thermal photon emission, and found that the time scale agrees with the observations. Based on our estimation, we analyzed the process of energy injection to GRB afterglow. We will show that the steady latent heat of quark star phase transition will continuously inject into the GRB afterglow in a form similar to that of a Poynting-flux-dominated outflow and naturally produce the shallow decay phase and the abrupt falloff after the plateau. We conclude that the latent heat of quark star phase transition is an important contribution to the shallow decay radiation in some GRB afterglows, and explains the long-lived plateau followed by an abrupt falloff, if pulsar-like stars are really (solid) quark stars.
In this article,we try to calculate the equation of state(EOS) of quantum chromodynamics(QCD) at finite chemical potential and zero temperature in the framework of a nonperturbative QCD model.Compared with the cold,perturbative EOS of QCD proposed by Fraga et al.,our EOS approaches more fastly to the free quark gas result at large chemical potential.It is expected that our EOS can provide a possible new tool for the study of neutron star.We also try to provide a direct approach for calculating quark number susceptibility and scalar susceptibility at finite chemical potential and zero temperature.
In this letter,we propose to introduce a new Abelian gauge field Bμcorresponding to the so-called β symmetry into the normal Quantum Electrodynamics in 2+1 dimensions(QED3)of γ representation.The resulting theory is shown to be equivalent to QED3 containing two flavors of two-component fermions with mass of an opposite sign.We also show that Bμfield can generate a Chern-Simons term in perturbation theory.A comparison is made between the induced Chern-Simons term in theγrepresentation and that in Pauli representation.
In this paper,we discuss the important role of the thermalization process in the initial distribution of QGP.We find that the negligible heat conduction inside QGP can be expressed as an effective Fourier law and we further analyse qualitatively the results caused by a thermalized initial condition.Based on this arguments,we construct a simple phenomenological model and work with the hydro code,and then we compare our results with the experimental data and the results of the standard initial model.It is found that,as we have argued,a thermalized initial condition suppresses the value of the elliptic flow.
