Measurement of CP Asymmetries and Branching Fractions in B0 -> pi+ pi-, B0 -> K+ pi-, B0 -> pi0 pi0, B0 -> K0 pi0 and Isospin Analysis of B -> pi pi Decays

Abstract

The authors present preliminary results of improved measurements of the CP-violating asymmetries and branching fractions in the decays B{sup 0} {yields} {pi}{sup +}{pi}{sup -}, B{sup 0} {yields} K{sup +}{pi}{sup -}, B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, and B{sup 0} {yields} K{sup 0}{pi}{sup 0}. This update includes all data taken at the {Upsilon}(4S) resonance by the BABAR experiment at the asymmetric PEP-II B-meson factory at SLAC, corresponding to 467 {+-} 5 million B{bar B} pairs. They find S{sub {pi}{pi}} = -0.68 {+-} 0.10 {+-} 0.03, C{sub {pi}{pi}} = -0.25 {+-} 0.08 {+-} 0.02, {Alpha}{sub K{sub {pi}}} = -0.107 {+-} 0.016{sub -0.004},{sup +0.006}, C{sub {pi}{sup 0}{pi}{sup 0}} = -0.43 {+-} 0.26 {+-} 0.05, {Beta}(B{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}) = (1.83 {+-} 0.21 {+-} 0.13) x 10{sup -6}, {Beta}(B{sup 0} {yields} K{sup 0}{pi}{sup 0}) = (10.1 {+-} 0.6 {+-} 0.4) x 10{sup -6}, where the first error is statistical and the second is systematic. They observe CP violation with a significance of 6.7{sigma} in B{sup 0} {yields} {pi}{sup -} and 6.1{sigma} in B{sup 0} {yields} K{sup +}{pi}{sup -}. Constraints on the Unitarity Triangle angle {alpha} are determined from the isospin relation between all B {yields} {pi}{pi} rates and asymmetries

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