Related papers: Background Suppression for $\mu\to e\gamma$ with P…
The cross-section for the process $\gamma + A \to \mu^+ + \mu^- + X$ is studied where the photon energy is of the order of several hundreds of GeV and where one of the leptons is scattered to large angles. This is of practical importance…
We point out at the peculiarity of B --> mu nu decay, namely the enhancement of the soft photon events which originate from the structure dependent part of the B --> mu nu gamma amplitude. This may be a dominant source of systematic…
A possible explanation for the discrepancy between electronic and muonic hydrogen measurements of the proton charge radius are new, lepton-universality violating interactions. Several new couplings and particles have been suggested that…
We report on a search for the flavor-changing neutral current decays $\Dz\to e^+e^-$ and $\Dz\to\mu^+\mu^-$, and the lepton-flavor violating decay $\Dz\to e^\pm\mu^\mp$. The measurement is based on $122 {fb}^{-1}$ of data collected by the…
Surprisingly, the contribution to the cosmic opacity to UHE ($E>10^{18} \, \rm eV$) $\gamma$-rays has been systematically computed so far for the $\gamma \gamma \to e^+e^-$ and $\gamma \gamma \to e^+ e^- e^+ e^-$ processes alone. We go a…
Vacuum polarization is a part of the initial-state radiative correction for the cross-section of $e^+e^-$ annihilation processes. In the energy region in the vicinity of narrow resonances $J/\psi$ and $\psi(3686)$, the vacuum polarization…
The process of Compton scattering $\gamma e^{\pm} \to \gamma e^{\pm}$ in a strongly magnetized medium of arbitrary temperature and zeroth chemical potential was considered. The analytical expressions for the partial cross section in the…
Minimal extensions of the Standard Model that are motivated by grand unified theories or superstring models with an E_6 symmetry can naturally predict heavy neutrinos of Dirac or Majorana nature. Such heavy neutral leptons violate the de-…
Lepton-flavor-violating decays of the type L->l gamma gamma (mu->e gamma gamma, tau->e gamma gamma, and tau->mu gamma gamma) are proposed as new probes of R-parity-violating supersymmetry. Non-penguin diagrams with a sneutrino that decays…
Simple dynamics, few available decay channels, and extremely well controlled radiative and loop corrections, make pion and muon decays a sensitive means for testing the underlying symmetries, the universality of weak fermion couplings, as…
A positive muon is a spin-1/2 particle. Beams of muons with all their spins polarized can be prepared and subsequently implanted in various types of condensed matter. The subsequent precession and relaxation of their spins can then be used…
The rare three body decay of a Higgs boson to a lepton-anti lepton pair and a photon has begun to attract attention, after the first evidence for the $H\to Z\gamma$ at CMS and ATLAS, which is a sub process of $H \to \ell^+ \ell^- \gamma$ .…
We consider the possibility of fingerprinting the presence of heavy additional Z' bosons that arise naturally in extensions of the standard model such as E_6 models and left-right symmetric models, through their mixing with the standard…
We study anomalous magnetic moments and flavor violating processes of $e$, $\mu$ and $\tau$ leptons. We use a data driven approach to investigate the implications of the present data on the parameters of a class of models, which has spin-0…
The present experimental status of searches for lepton flavor violating decays of the $\tau$ lepton to a lighter mass lepton and a photon or a pseudoscalar meson is presented. The results obtained are from $e^+e^-$ annihilation data…
We revisit the potential of a Linear Collider concerning the study of lepton flavour violation, in view of new LHC bounds and of the (very) recent developments in lepton physics. Working in the framework of a type I supersymmetric seesaw,…
A long-lived very light pseudoscalar boson would favor lepton flavor violating transitions of charged leptons. Its implications on the l_i --> l_j \gamma \gamma, and l_i --> l_j e^+ e^- transitions are investigated. Assuming 2 m_e < m_\phi…
Simple dynamics, few available decay channels, and highly controlled radiative and loop corrections, make pion and muon decays a sensitive means of exploring details of the underlying symmetries. We review the current status of the rare…
We present a detailed and complete calculation of the doubly charged Higgsino contribution to the decays mu--> e photon and mu--> 3e and to the anomalous magnetic moment of the muon within the left-right supersymmetric model. We include the…
The constructions of the new high-intensity muon beamlines are progressing in facilities around the world, and new physics searches related to the muons are expected. The facilities can observe the transverse positron polarization of the…