Measurement of branching fractions and CP violation in B → ηcK and observation of B± → pp̅K±

Abstract

We report measurements of branching fractions for charged and neutral B -> ncK decays, and determine the nc mass and width. The results are based on an analysis of 29.1 fb-1 of data collected by the Belle detector at KEKB. We also report a measurement of the CP violation parameter sin(2ø1) in B0 -> ncK0s based on an analysis of a 78 fb-1 of data sample. We report the observation of the decay mode B± -> ppK± based on an analysis of 29.4 fb -1 of data collected by the Belle detector at KEKB. This is the first example of a b -> s transition with baryons in the final state. The pp mass spectrum in this decay is inconsistent with phase space and is peaked at low mass. The branching fraction for this decay is measured to be B(B± -> ppK±) = (4.7(stat+1.1 -0.9) ± 0.5(syst)) x 10-6. We also report upper limits for the decays B0 -> ppKs and B± -> ppπ±.