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Based on the 110M ψ(3686) data sample which has been collected by BESIII at year 2009, many χcJ decay modes have been measured, such as χcJ → π0π0, χcJ → ηη, χcJ → VV, χcJ → γV, and so on. Results presented in this document are preliminary. [ABSTRACT FROM AUTHOR]

After a decade of design, construction, improvement, data-taking, simulation, and analysis, the TRIUMF Weak Interaction Symmetry Test (TWIST) muon decay parameter measurements are nearly complete. While the final results are yet to be unblinded, a preliminary estimate of the final precision is available. The goal of an order-of-magnitude improvement on pre-TWIST precisions for the ρ, δ, and Pμξ decay parameters has essentially been achieved, making possible some tighter constraints on parameters of the left-right symmetric extension to the standard model as well as the fundamental coupling constants of the muon. [ABSTRACT FROM AUTHOR]

The MEG experiment started a search for a lepton violating (LFV) muon decay, μ+→e+γ, at Paul Scherrer Institut(PSI) in Switzerland. The LFV muon decay does not occur in the standard model, while new theories, such as super symmetric grand unified theory and seesaw model of neutrinos, predict observable branching ratio just below the current upper limit (1.2×10-12). MEG is designed to improve the sensitivity by two orders of magnitude. In this article, the system of the MEG experiment and its data taking in 2008 are described. [ABSTRACT FROM AUTHOR]

The transverse polarization components of the e+ from the decay of polarized μ+ have been measured at the Paul Scherrer Institute by annihilating in flight the decay positrons with polarized electrons. The use of a stroboscopic method greatly reduces systematic errors. The energy dependence of the transverse polarization component PT1, which lies in the plane defined by muon spin and positron momentum, yields the low energy parameter η = (-2 ± 8) × 10-3 and thus an improved model-independent value of the Fermi coupling constant. For the transverse polarization PT2, averaged over the positron energy, we obtain = (-4 ± 8) × 10-3. This improves the previous limit on the violation of time invariance in muon decay by a factor of three. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

With the discovery of neutrino masses, it is clear that lepton-flavor is no longer a conserved quantity. This means that charged-lepton flavor violating processes (CLFV) including rare muon and tau decays (e.g. μ → eγ, τ → μe+e-) are, in principle, observable. I review some phenomenological aspects of CLFV (concentrating on rare muon processes) and briefly discuss a few Standard Model extensions that predict a “large” rate for CLFV. In several of these extensions there are deep relations between the physics that generates neutrino masses and mixing and CLFV. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The phsysics motivations for this experiment are presented. A general description of the experiment and of the R&D status of each sub-detector is given. The sensitivity of the experiment and its time schedule are finally presented. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Building on the rare pion and muon decay results of the PIBETA experiment, the PEN collaboration has undertaken a precise measurement of Bπe2≡Re/μπ, the π+ → e+ν(γ) decay branching ratio, at the Paul Scherrer Institute, to reduce the present 40× experimental precision lag behind theory to ∼6 - 7×. Because of large helicity suppression, Re/μπ is uniquely sensitive to contributions from non-(V - A) physics, making this decay a particularly suitable subject of study. Even at current precision, the experimental value of Bπe2 provides the most accurate test of lepton universality available. During runs in 2008-10, PEN has accumulated over 2 × 107 πe2 events; a comprehensive maximum-likelihood analysis is currently under way. The new data will also lead to improved precision of the earlier PIBETA results on radiative π and μ decays. [ABSTRACT FROM AUTHOR]

We use experimental limits on the neutrino mass to derive model-independent upper bounds on various muon decay parameters. We find that the bounds obtained in this way are improved by more than three orders of magnitude over current experimental limits. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The transverse polarization components of the positrons from the decay of polarized muons have been measured at the Paul Scherrer Institute by annihilating in flight the decay positrons with polarized electrons. The use of a stroboscopic method greatly reduces systematic errors. The energy dependence of the transverse polarization component PT1, which lies in the plane defined by muon spin and positron momentum, yields the low energy parameter η = (-2 ± 8) × 10 -3 and thus an improved model-independent value of the Fermi coupling constant. For the transverse polarization PT2, averaged over the positron energy, we obtain = (-4 ± 8) × 10-3. This improves the previous limit on the violation of time invariance in muon decay by a factor of three. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]