分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: In this invited short "news and views", we review very briefly the history of pentaquark studies and the recent observations of the tetraquark and pentaquark states. We also discuss further experimental studies such as at Belle-II.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: With the recent measurements of psi' and J/psi decay into octet-baryon pairs, we study the relative phase between the strong and the electromagnetic amplitudes, and find a large phase by fitting the present data. The fits take into account the details of experimental effects, including energy spread and initial state radiation. We also predict some branching fractions of psi' decays and the continuum production rates at the J/psi mass based on the relative phase and absolute amplitudes obtained from the fits.
分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: The charged lepton flavor violation process is a clean and sensitive probe of new physics beyond the Standard Model. A sensitivity study is performed to the process τ−→γμ− based on a 3~fb−1 inclusive Monte Carlo sample of e+e− collisions at a center-of-mass energy of 4.26 or 4.6~GeV, in the framework of the BESIII software system. The 90\% confidence level upper limits on $\BR(\tau^- \to \gamma \mu^-)$ are estimated assuming no signal is produced. We also obtain the sensitivity on $\BR(\tau^- \to \gamma \mu^-)$ as a function of the integrated luminosity, to serve as a reference for the HIEPA being proposed in China. It is found that 6.34~ab−1 are needed to reach the current best upper limit of 4.4×10−8 and about 2510~ab−1 are needed to reach a sensitivity of 10−9 if the detector design is similar to that of BESIII.