Improved Measurements of Branching Fractions for B0 -> pi+pi-, K+pi-, and Search for K+K- at BaBar

TL;DR

This paper reports precise measurements of branching fractions for B0 decays into pi+pi- and K+pi-, and sets an upper limit for the K+K- decay, using a large data sample from BaBar.

Contribution

It provides updated and more accurate measurements of B0 decay branching fractions and searches for rare decay modes, improving the understanding of charmless B decays.

Findings

Br(B0 -> pi+pi-) = 5.5 +- 0.4 +- 0.3

Br(B0 -> K+pi-) = 19.2 +- 0.6 +- 0.6

Br(B0 -> K+K-) < 0.40 at 90% CL

Abstract

We present preliminary measurements of branching fractions for the charmless two-body decays B0 -> pi+pi- and K+pi-, and a search for B0 -> K+K- using a data sample of approximately 227 million BBbar decays. Signal yields are extracted with a multi-dimensional maximum likelihood fit, and the efficiency is corrected for the effects of final-state radiation. We find the charge-averaged branching fractions (in units of 10^{-6}): Br(B0 -> pi+pi-) = 5.5 +- 0.4 +- 0.3, Br(B0 -> K+pi-) = 19.2 +- 0.6 +- 0.6, Br(B0 -> K+K-) = < 0.40. The errors are statistical followed by systematic, and the upper limit on K+K- represents a confidence level of 90%.