Modern Physics Letters A

We report on the current status of semi-leptonic B_(s) decays, including rare decays, and the extraction of the absolute values of the CKM matrix elements |V_cb| and |V_ub|.

In this paper, we show the simple expression for the energy density of the thermal-equilibrium Friedmann–Robertson–Walker (TEFRW) universe and study the problem how to describe it by using some field models. We analyze the properties of the quintessence field in the quintessence model, calculate the tachyon potential in the tachyon model and point out that the latter model cannot give the whole description for the TEFRW universe. It is found that the two-field model can be responsible for describing the whole evolution process of the TEFRW universe.

The variation of β-decay lifetime of the ground state of various isotope chains display a systematic behavior with respect to the ratio of the number of valence neutron particles or holes and the maximum possible number of neutron particles or holes in that shell. Lifetimes, depending on the particle or hole nature of the protons and neutrons, as well as whether they belong to the same shell or not, are found to exhibit similar increasing or decreasing trends and display similar behavior with respect to variation of the above-mentioned ratio.

In this work, we study single, double and triple heavy-flavor baryons using the hypercentral approach in the framework of the non-relativistic quark model. Considering two different confining potentials and an improved form of the hyperfine interaction, we calculate the ground-state masses of heavy baryons and also the ground-state magnetic moments of single charm and beauty baryons with J^P = 3/2⁺. The obtained results are in good agreement with experimental data and those of other works.

A new kind of charge coherent state called a Z_p-graded charge coherent state is constructed by using the complex solution of the equation q^p = 1. The p-1 charge operators are also explicitly constructed. We explicitly investigate some nonclassical properties for the Z₃-graded charge coherent state.

In this paper, we provide an alternative method to study the area spectrum of certain classes of extremal black holes which have near-horizon geometry as warped AdS. We argue that previous methods which are based on the existence of quasinormal modes may not be applicable in the extremal limit. The topology difference of the near-horizon geometry between non-extremal and extremal black holes implies a separate treatment is needed to study the area discreteness in the extremal limit. To be specific, we will study area spectrum of supersymmetric BMPV black holes/black rings and Reissner–Nordström (RN) black holes at the extremal limit. Inspired by the recently established Kerr/CFT and RN/CFT correspondence, we propose a new way to quantize the area regardless of the (non-)existence of quasinormal modes or zero Hawking temperature. At last, we propose a dilute gas model and harmonic oscillator model which have same degrees of freedom as the dual CFT.

It is shown that the geodesics with negative energy for rotating black holes cannot originate or terminate inside the ergosphere. Their length is always finite and this leads to conclusion that they must originate and terminate inside the gravitational radius of the ergosphere.