Observation of New Charmless Decays of Bottom Hadrons

TL;DR

This paper reports the first observations of several charmless decays of bottom hadrons, including B0s and Lambda_b, with precise measurements of their branching ratios, using data from the Fermilab Tevatron.

Contribution

It provides the first experimental evidence for specific charmless bottom hadron decays and measures their branching fractions with improved precision.

Findings

First observation of B0s->K-pi+ decay with 8.2 sigma significance

First observation of Lambda_b decays to p pi and pK with 6.0 and 11.5 sigma significance

Set upper limit on B0s->pi+pi- decay branching fraction

Abstract

We search for new charmless decays of neutral b-hadrons to pairs of charged hadrons with the upgraded Collider Detector at the Fermilab Tevatron. Using a data sample corresponding to 1 fb-1 of integrated luminosity, we report the first observation of the B0s->K-pi+ decay, with a significance of 8.2 sigma, and measure BR(B0s->K-pi+)= (5.0+-0.7(stat)+-0.8(syst))*10^{-6}. We also report the first observation of charmless b-baryon decays in the channels Lambda_b -> p pi and Lambda_b -> pK with significances of 6.0 sigma and 11.5 sigma respectively, and we measure BR(Lambda_b->p pi-) = (3.5+-0.6(stat)+-0.9(syst))*10^{-6} and BR(Lambda_b->p K-) = (5.6+-0.8(stat)+-1.5(syst))*10^{-6}. No evidence is found for the decays B0->K+K- and B0s -> pi+pi-, and we set an improved upper limit BR(B0s -> pi+pi-) < 1.2*10^{-6}$ at the 90% confidence level. All quoted branching fractions are measured using BR(B0->K+pi-)$ as a reference.