分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-09-17
摘要: Within the framework of the heavy quark effective theory, QCD sum rules are used to calculate the masses of p-wave ¯cs states. The results for 0+ and 1+ states with the angular momentum of the light component jl = 1/2 are consistent with the experimental values for Ds(2317) and Ds(2457), respectively.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2017-08-24
摘要: We study the energy level statistics of the states in U(5) and O(6) dynamical symmetries of the interacting boson model and the high spin states with backbending in U(5) symmetry. In the calculations, the degeneracy resulting from the additional quantum number is eliminated manually. The calculated results indicate that the finite boson number N effect is prominent. When N has a value close to a realistic one, increasing the interaction strength of subgroup O(5) makes the statistics vary from Poisson-type to GOE-type and further recover to Poisson-type.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2017-08-24
摘要: We study the energy level statistics of the states in E(5) and X(5) dynamical symmetries. The calculated results indicate that the statistics of E(5) symmetry is regular and follows Poisson statistics, while that of X(5) symmetry involves two maxima in the nearest neighbor level spacing distribution P(s) and the ∆3 statistics follows the GOE statistics. It provides an evidence that the X(5) symmetry is at the critical point exhibiting competing degrees of freedom
分类: 物理学 >> 核物理学 提交时间: 2016-09-02
摘要: A careful study on the nature of the Z_c(3900) resonant structure is carried out in this work. By constructing the pertinent effective Lagrangians and considering the important final-state-interaction effects, we first give a unified description to all the relevant experimental data available, including the J/\psi\pi and \pi\pi invariant mass distributions from the e^+e^-\to J/\psi\pi\pi process, the h_c\pi distribution from e^+e^-\to h_c\pi\pi and also the D\bar{D}^{*} spectrum in the e^+e^-\to D\bar{D}^{*}\pi process. After fitting the unknown parameters to the previous data, we search the pole in the complex energy plane and only find one pole in the nearby energy region in different Riemann sheets. Therefore we conclude that Z_c(3900) is of D\bar{D}^* molecular nature, according to the pole counting rule method. We emphasize that the conclusion based upon pole counting method is not trivial, since both the D\bar{D}^{*} contact interactions and the explicit Z_c exchanges are introduced in our analyses and they lead to the same conclusion.