Evidence for B+→hcK+ and observation of ηc(2S)→pp¯π+π−

Abstract

A search for the decays B+→hcK+ and B0→hcKS0 is performed. Evidence for the decay B+→hcK+ is found; its significance is 4.8σ. No evidence is found for B0→hcKS0. The branching fraction for B+→hcK+ is measured to be (3.7-0.9+1.0 -0.8+0.8)×10-5; the upper limit for the B0→hcKS0 branching fraction is 1.4×10-5 at 90% C.L. In addition, a study of the ppπ+π- invariant mass distribution in the channel B+→(ppπ+π-)K+ results in the first observation of the decay ηc(2S)→ppπ+π- with 12.1σ significance. The analysis is based on the 711 fb-1 data sample collected by the Belle detector at the asymmetric-energy e+e- collider KEKB at the (4S) resonance.