The vacuum fluctuation(VF) effects on the properties of the hyperonic neutron star matter are investigated in the framework of the relativistic mean field(RMF) theory. The VF corrections result in the density dependence of in-medium baryon and meson masses. We compare our results obtained by adopting three kinds of meson-hyperon couplings. The introduction of both hyperons and VF corrections softens the equation of state(EoS) for the hyperonic neutron star matter and hence reduces hyperonic neutron star masses. The presence of the δ field enlarges the masses and radii of hyperonic neutron stars. Taking into account the uncertainty of meson-hyperon couplings, the obtained maximum masses of hyperonic neutron stars are in the range of 1.33M –1.55M.
The masses of some orbitally and radially excited heavy-light mesons are calculated in Regge phenomenology. The results are in reasonable agreement with the experimental data and those given in many other theoretical approaches. Based on the calculation, we suggest that the recently observed D（2550）, D（2600） and D（2760） can be assigned as the charmed members of the 21 S0 , 23 S1 and 13 D1 multiplets, respectively. Ds1* （2700）± may be assigned as the charm-strange member of the 23 S1 state. The results may be helpful in understanding the nature of current and future experimentally observed heavy-light mesons.
We analyze the radiative leptonic Bc decay Bc-→τ-νˉτγ in the Standard Model and the twoHiggs-doublet model using the non-relativistic constituent quark model.The results confirm that this channel is experimentally promising in view of the large number of Bc mesons which are expected to be produced at future hadron facilities.We also find that this decay is sensitive to the parameters of the two-Higgs-doublet model,and it can be tested in future experiments.
In the framework of factorization, we study direct CP violation in the decays of B(s) → J/ψP(V) (P(V) refer to the pseudoscalar (vector) meson). The CP violation depends strongly on Cabibbo-Kobayashi- Maskawa (CKM) matrix elements and the effective parameter, Nc. The recent experimental data for the branching ratios of B(s) → J/ψP(V) are accurate enough and we can give a strong constraint on the range of Nc. We find that the CP violating asymmetry is consistent with the available experiment values for the b → d transition, and a little smaller than the b → s transition. We also predict the CP violation of other decay channels for B(s) → J/ψP(V). We expect our results can give valuable guidance for experiments.
The phenomenon of the near ppˉ-threshold enhancement observed in the J/ψ→γ pp decay is studied by using the enhancement factor method with a simpler one-pion-exchange potential between p and p. The Jost function caused by the mentioned potential is perturbatively calculated in the zero-th order approximation, and the corresponding enhancement factor is obtained. It is found that such a final state interaction offers an important contribution to the decay width near the ppˉ-threshold, although it is not large enough. To explain the decay data, a phenomenological factor G(p) with the form of 285500/(m 2 π + p 2 ) should be introduced. A further calculation including the p-dependent bare T -matrix, a more realistic N ˉ N potential and the contribution from the higher-order wave functions would provide a better understanding of the decay data and even the existence of the baryonium ppˉ. The near ppˉ-threshold behavior of the decay width in the J/ψ→π 0 pp process is also discussed.
