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VOLUME 91 (2010) | ISSUE 4 |
PAGE 175
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How the recent BABAR data for P→ γγ* affect the Standard Model predictions for the rare decays P→ l+l-
A. E. Dorokhov
Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, 141980 Dubna, Moscow region, Russia Institute for Theoretical Problems of Microphysics, Moscow State University, 119899 Moscow, Russia
Abstract
Measuring the lepton anomalous magnetic moments (g-2) and the
rare decays of light pseudoscalar mesons into lepton pairs , serve as important tests of the Standard Model. To reduce the
theoretical uncertainty in the standard model predictions, the data on the
charge and transition form factors of the light pseudoscalar mesons play a
significant role. Recently, new data on the behavior of the transition form
factors P→γγ* at large momentum transfer were supplied by the
BABAR collaboration. There are several problems with the theoretical
interpretation of these data: 1) An unexpectedly slow decrease of the pion
transition form factor at high momenta, 2) the qualitative difference in the
behavior of the pion form factor and the η and form
factors at high momenta, 3) the inconsistency of the measured ratio of the
η and form factors with the predicted one. We comment on
the influence of the new BABAR data on the rare decay branchings.
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