A new measurement of Bπe2, the π+→e+ν(γ) decay branching ratio, is currently under way at the Paul Scherrer Institute. The present experimental result on Bπe2 constitutes the most accurate test of lepton universality available. The accuracy, however, still lags behind the theoretical precision by over an order of magnitude. Because of the large helicity suppression of the πe2 decay, its branching ratio is susceptible to significant contributions from new physics, making this decay a particularly suitable subject of study.
@article{arxiv.0909.4358,
title = {PEN experiment: a precise measurement of the pi+ -> e+ nu decay branching fraction},
author = {PEN Collaboration and D. Pocanic and L. P. Alonzi and V. A. Baranov and W. Bertl and M. Bychkov and Yu. M. Bystritsky and E. Frlez and V. A. Kalinnikov and N. V. Khomutov and A. S. Korenchenko and S. M. Korenchenko and M. Korolija and T. Kozlowski and N. P. Kravchuk and N. A. Kuchinsky and D. Mekterovic and D. Mzhavia and A. Palladino and P. Robmann and A. M. Rozhdestvensky and S. N. Shkarovskiy and U. Straumann and I. Supek and P. Truoel and Z. Tsamalaidze and A. van der Schaaf and E. P. Velicheva and V. P. Volnykh},
journal= {arXiv preprint arXiv:0909.4358},
year = {2010}
}
Comments
4 pages, 3 figures, talk given at the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), La Jolla/San Diego, CA, 26-31 May 2009; to appear in Proceedings to be published by the American Institute of Physics