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

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.

6 pages, 1 figure

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• New Physics at a Super Flavor Factory
• Measurements of Branching Fractions and Direct CP Asymmetries for B -> K pi, B->pi pi and B->to KK Decays
• Measurements of Direct CP Violating Asymmetries in Charmless Decays of Strange Bottom Mesons and Bottom Baryons
• Study of B0 -> pi0 pi0, B -> pi pi0, and B -> K pi0 Decays, and Isospin Analysis of B -> pipi Decays
• Observation of New Charmless Decays of Bottom Hadrons
• Charmless Hadronic B-Meson Decays
• B_s -> phi rho^0 and B_s -> phi pi^0 as a handle on isospin-violating New Physics
• Searching For New Physics With B to K pi Decays
• Search for charmonium and charmonium-like states in Υ(2S) radiative decays
• Search for charmonium and charmonium-like states in ${\rm Y}(1S)$ radiative decays
• The effects of a family non-universal Z-prime boson on B--->pipi decays
• Measurement of $e^{+}{e}^{-}\to \omega {\pi }^0$, $K^{\ast }(892)\bar{K}$ and $K_2^{\ast }(1430)\bar{K}$ at $\sqrt{s}$ near 10.6 GeV
• Measurement of exclusive ${\rm Y}(1S)$ and ${\rm Y}(2S)$ decays into Vector-Pseudoscalar final states
• The B ---> π K puzzle and the Bulk Randall-Sundurm model
• Sum rules for B-->pi eta('), K eta('), eta(') eta(') decays
• Observation of the rare baryonic decay $B^{+}\to p\bar{\Lambda }$ and measurement of its weak decay parameter