Elsevier

Physics Letters B

Volume 441, Issues 1–4, 26 November 1998, Pages 403-409
Physics Letters B

New bound on γ from B±πK decays

https://doi.org/10.1016/S0370-2693(98)01194-0Get rights and content

Abstract

A bound on the angle γ of the unitarity triangle is derived using experimental information on the CP-averaged branching ratios for the rare decays B±π±K0 and B±π0K±. The theoretical description is cleaner than the Fleischer–Mannel analysis of the decays B±π±K0 and B0πK± in that the two decay rates differ only in a single isospin amplitude, which has a simple structure in the SU(3) limit. As a consequence, electroweak penguin contributions and strong rescattering effects can be taken into account in a model-independent way. The resulting bound excludes values of cosγ around ≈0.6 and is thus largely complementary to indirect constraints derived from a global analysis of the unitarity triangle.

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Acknowledgements

Part of this work was done during the Workshop on Perturbative and Non-Perturbative Aspects of the Standard Model at St. John's College, Santa Fe, July–August 1998. We would like to thank the organizer Rajan Gupta, as well as the participants of the workshop, for providing a stimulating atmosphere and for many useful discussions. We are grateful to Michael Gronau, Alex Kagan, Sheldon Stone and Lincoln Wolfenstein for helpful comments on the manuscript. One of us (J.L.R.) was supported in part

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