Measurements of ψ′→p̄K+Σ0 and χcJ→p̄K+Λ

Abstract

Using a sample of 1.06 x 10(8) psi' mesons collectedwith the BESIII detector at the BEPCII e(+)e(-) collider and chi(cJ) mesons produced via radiative transitions from the psi', we report the first observation for psi' -> (p) over barK(+)Sigma(0) + c.c. (charge conjugate), as well as improved measurements for the chi(cJ) hyperon decays chi(cJ) -> (p) over barK(+) Lambda + c.c. The branching fractions are measured to be B(psi' -> (p) over barK(+) Sigma(0) + c.c) = (1.67 +/- 0.13 +/- 0.12) x 10(-5), B(chi(c0) -> (p) over barK(+) Lambda + c.c) = (13.2 +/- 0.3 +/- 1.0) x 10(-4), B(chi(c1) -> (p) over barK(+) Lambda + c.c) = (4.5 +/- 0.2 +/- 0.4) x 10(-4), and B(chi(c2) -> (p) over barK(+) Lambda + c.c) = (8.4 +/- 0.3 +/- 0.6) x 10(-4), where the first error is statistical, and the second is systematic. In the decay of chi(c0) -> (p) over barK(+) Lambda + c.c:, an anomalous enhancement near threshold is observed in the invariant mass distribution of (p) over bar Lambda + c.c:, which cannot be explained by phase space. DOI: 10.1103/PhysRevD.87.012007