Observation of B+ →p Λ ̄ K+K- and B+ → p ̄ Λk+K+ OBSERVATION of ... P.-C. LU et al.

Abstract

We report the study of B+→pΛ̄K+K- and B+→p̄ΛK+K+ decays using a 772×106 BB̄ pair data sample recorded on the Ï (4S) resonance with the Belle detector at KEKB. The following branching fractions are measured: B(B+→pΛ̄K+K-)=(4.10-0.43+0.45±0.50)×10-6, B(B+→p̄ΛK+K+)=(3.70-0.37+0.39±0.44)×10-6, B(ηc→pΛ̄K-+c.c.)=(2.83-0.34+0.36±0.35)×10-3 and B(B+→pΛ̄φ)=(7.95±2.09±0.77)×10-7, where c.c. denotes the corresponding charge-conjugation process. The intermediate resonance decays are excluded in the four-body decay measurements. We also find evidence for B(ηc→Λ(1520)Λ̄+c.c.)=(3.48±1.48±0.46)×10-3 and B(B+→Λ(1520)Λ̄K+)=(2.23±0.63±0.25)×10-6. No significant signals are found for J/ψ→Λ(1520)Λ̄+c.c. and B+→Λ̄(1520)ΛK+; we set the 90% confidence level upper limits on their decay branching fractions as <1.80×10-3 and <2.08×10-6, respectively.