Possible structures and properties of some excited states of Λ c + dynamically generated in the coupled-channel P-wave meson-baryon scattering are studied by solving the Bethe-Salpeter(BS) equation in the framework of the Chiral Unitary Approach.It is shown that both Λ c + (2765) and Λ c + (2940) could be generated dynamically and could be compound states with multi-configuration molecular-like structures.The couplings of the generated states to various reaction channels are also calculated.Moreover,two highly excited states,Λ c + (3024) and Λ c + (3134),are predicted.
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.
The double-differential neutron emission cross sections for n+56Fe reactions at incident energies of 7-13 MeV at different angles are calculated by the UNF(abbreviation for unified,2009 Version) code,which is based on the unified Hauser-Feshbach and exciton model.The results indicate that the higher the incident energies,the better the results,although there are some discrepancies between the calculated results and the measured data for natural iron.These discrepancies are analyzed in detail in this paper.In addition,the calculated results are also compared with the evaluated results of ENDF/B.0 and JEFF-3.1.1 near the angle of 90°at incident energies of 8.17 and 11.5 MeV,respectively.
