Related papers: Wrong-Helicity Electrons in Radiative Muon Decay
We consider the O(alpha^2) hadronic corrections to the energy spectrum of the decay electron in muon decay. We find that the correction can be described, within good approximation, by a linear function in the electron energy. Explicit…
At the kinematic endpoint of zero recoil physical momenta are parallel which leads to symmetries in the decay distributions. We implement this observation for decays of the type $A \to (B_1 B_2) C$ by extending the helicity formalism to…
O(alpha^2 ln^2(m_mu/m_e)) QED corrections to the electron spectrum and angular distribution in muon decay are evaluated. Impact on the determination of Michel parameters is estimated. Current theoretical uncertainty in the muon decay…
Recently we considered the electromagnetic decays of the orbitally-excited SU(6) 70-plet baryons in large-N_c QCD, fitting to the helicity amplitudes measured in photoproduction experiments. Using the results of this analysis, we predict…
The gluon polarisation in the nucleon has been determined by detecting charm production via D0 meson decay to charged K and pi in polarised muon scattering off a longitudinally polarised deuteron target. The data were taken by the COMPASS…
A model-independent expression for the Dalitz plot of the semileptonic decays of a neutral kaon $K_{\mu 3}^0$, including radiative corrections to order $\mathcal{O}[(\alpha / \pi )(q/M_1)]$, where $q$ is the four-momentum transfer and $M_1$…
We give a general parameterization of the Lambda_b --> Lambda(1520) gamma decay amplitude, applicable to any strange isosinglet spin-3/2 baryon, and calculate the branching fraction and helicity amplitudes. Large-energy form factor…
We compute the dominant, logarithmically enhanced radiative corrections to the electron spectrum in the bound muon decay in the whole experimentally interesting range. The corrected spectrum fits well the TWIST results. The remaining…
We discuss the concept of handedness applied to $\tau$ production in $e^+e^-$ annihilations with $\tau$ decaying into $a_1\nu_\tau \to 3\pi\nu_\tau$. The $a_1\to 3\pi$ decay is particularly interesting since it (together with $h_1\to 3\pi$)…
Neutrinos with a magnetic moment $\mu$ change their helicity when interacting with an electromagnetic field. Various aspects of this effect have been described as spin precession, spin-flip scattering, and magnetic Cherenkov radiation.…
The beam-helicity asymmetry in associated electroproduction of real photons, $ep\to e\gamma \pi N$, in the $\Delta$(1232)-resonance region is measured using the longitudinally polarized HERA positron beam and an unpolarized hydrogen target.…
We present a new measurement of the tau neutrino helicity, hnu and the tau Michel parameters rho, eta, xi and the product delta xi. The analysis exploits the highly polarized SLC electron beam to extract these quantities directly from a…
We studied the radiative muon decay $\mu^+ \to e^+\nu\bar{\nu}\gamma$ by using for the first time an almost fully polarized muon source. We identified a large sample (~13000) of these decays in a total sample of 1.8x10^14 positive muon…
We calculate the rate of the decay $\mu \to e\gamma$ and the electric dipole moment of the electron in the left-right supersymmetric model when the breaking of parity occurs at a considerably large scale. The low-energy flavor violation in…
We consider the impact of O(alpha^2) hadronic corrections to the energy spectrum of the decay electron in muon decay. We find that the correction can be described, within good approximation, by a linear function in the electron energy.…
In this paper we study the lepton polarization asymmetry for the simileptonic OZI-forbidden annihilation B^-_c->\eta' \ell^- \bar{\nu} decay where \ell=\mu, \tau. Our results show that the branching ratio turn out to be of order 10^{-4}.…
Perturbative and nonperturbative QCD corrections to semileptonic B decay rates are calculated and given in analytical and numerical forms. We present the analytic expression for the double distribution in hadronic mass and electron energy…
We present a systematic study of $\Lambda_c^+ \to {\cal B}_q \ell^+ \nu_\ell $ with ${\cal B}_q = (\Lambda, n)$ and $\ell =( e, \mu)$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD…
Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta\rightarrow 2\gamma$ and $\eta\rightarrow…
We study the equilibration of right-handed electrons in the symmetric phase of the Standard Model. Due to the smallness of the electron Yukawa coupling, it happens relatively late in the history of the Universe. We compute the equilibration…