Improved measurements of branching fractions for B -> K pi and B -> pi pi decays

TL;DR

This paper presents improved measurements of B meson decay branching fractions into K pi and pi pi final states, providing data that tests the Standard Model and searches for signs of new physics.

Contribution

The study offers the most precise measurements to date of B -> K pi and pi pi branching fractions and their ratios, consistent with Standard Model predictions.

Findings

Ratios R_c and R_n are approximately 1.08 with uncertainties.

Results are consistent with Standard Model expectations.

No evidence of enhanced electroweak penguin contributions.

Abstract

We report improved measurements of branching fractions for B -> K pi and B -> pi pi decays based on a data sample of 449 million B Bbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+e^- collider. We also calculate the ratios of partial widths for the decays B -> K pi and pi pi, namely R_c = 1.08 +- 0.06 +- 0.08 and R_n = 1.08 +-0.08 +0.09-0.08, where the first and second errors are statistical and systematical, respectively. These ratios are sensitive to enhanced electroweak penguin contributions from new physics; the new measurements are, however, consistent with Standard Model expectations.