[SEMINARI]: Dr. Neubert: New Strategies for learning the weak phase gamma.

[Arcadi Santamaria]

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                              S E M I N A R I

            [Image]    Departament de Física Teòrica     [Image]
                          Universitat de València
                      46100 Burjassot (València) Spain

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               New Strategies for Learning the Weak Phase $\gamma$

                            Dr. Matthias Neubert

                                   (CERN)

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                     Aula de Seminaris de Física Teòrica
                   Tuesday 27 of October of 1998 at 12:00
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                                    Resum

A new bound on the angle $\gamma$ of the unitarity triangle is derived using
  experimental information on the CP-averaged branching ratios for the rare
   decays $B^\pm\to\pi^\pm K^0$ and $B^\pm\to\pi^0 K^\pm$. The theoretical
  description is cleaner than the Fleischer-Mannel analysis 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 $\cos\gamma$
around 0.6 and is thus largely complementary to indirect constraints derived
 from a global analysis of the unitarity triangle. We also describe a method
   which allows to {\em determine} $\gamma$ using a generalization of the
       Gronau-Rosner-London approach that includes electroweak penguin
                               contributions.

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