Probing the Standard Model via rare pion and muon decays

Abstract

The PIBETA collaboration has used a non-magnetic pure CsI calorimeter operating at the Paul Scherrer Institute to collect the world's largest sample of rare pion and muon decays. We have extracted the absolute pi+ -> pi0 e+ nu decay branching ratio with the 0.55 % total uncertainty. The pi+ -> e + nu gamma data set was used to extract weak axial and vector form factors F_A and F_V, yielding a significant improvement in the precision of F_A and F_V. The mu+ -> e+ nu nu gamma distributions were well described with the two-parameter (rho_SM,eta_bar=0) solution. These results bring major improvements in accuracy over the current Particle Data Group listings and agree well with the predictions of the Standard Model.

arXiv comment5 pages, 5 postscript figures, 2 tables, LaTeX, presented at the International Workshop e+e- Collisions from phi to psi, February 27 - March 2, 2006, Budker Institute of Nuclear Physics, Novosibirsk, Russia (http://www.inp.nsk.su/conf/phipsi06), to appear in Nuclear Physics B (Proceedings Supplement)

References in corpus (8)

• Big Bang Nucleosynthesis (in "The Review of Particle Properties" 2004)
• Precise Measurement of the Pi+ -> Pi0 e+ nu Branching Ratio
• Short and Long Distance Effects in the Decay $\tau \to \pi {\nu }_{\tau }(\gamma )$
• Precise Measurement of the Pion Axial Form Factor in the Pi+ -> e+ nu gamma Decay
• The pionic beta decay in chiral perturbation theory
• Design, Commissioning and Performance of the PIBETA Detector at PSI
• Radiative corrections of $O(\a)$ for pion beta decay in the light-front quark model
• On the analysis of the pi -> e nu gamma experimental data

Cited by in corpus (2)

• On the Radiative Pion Decay
• Chiral corrections to ${\pi }^{-}\gamma \to 3\pi$ processes at low energies