Study of ψ(3770) decaying to baryon anti-baryon pairs

Abstract

To study the decays of ψ(3770) going to baryon anti-baryon pairs (BB¯), all available experiments of measuring the cross sections of e+e−→BB¯ at center-of-mass energy ranging from 3.0 GeV to 3.9 GeV are combined. To relate the baryon octets, a model based on the SU(3) flavor symmetry is used and the SU(3) breaking effects are also considered. Assuming the electric and magnetic form factors are equal (|GE|=|GM|), a global fit including the interference between the QED process and the resonant process is performed. The branching fraction of ψ(3770)→BB¯ is determined to be (2.4±0.8±0.3)×10−5, (1.7±0.6±0.1)×10−5, (4.5±0.9±0.1)×10−5, (4.5±0.9±0.1)×10−5, (2.0±0.7±0.1)×10−5, and (2.0±0.7±0.1)×10−5 for B=p,Λ,Σ+,Σ0,Ξ− and Ξ0, respectively, where the first uncertainty is from the global fit and the second uncertainty is the systematic uncertainty due to the assumption |GE|=|GM|. They are at least one order of magnitude larger than a simple scaling of the branching fraction of J/ψ/ψ(3686)→BB¯.