相关论文: Muonium Decay
We calculate the radiative corrections to the unpolarized and the four polarized spectrum and rate functions in the leptonic decay of a polarized $ \mu $ into a polarized electron. The new feature of our calculation is that we keep the mass…
Radiative deexcitation (RD) of the metastable 2S state of muonic protium and deuterium atoms has been observed. In muonic protium, we improve the precision on lifetime and population (formation probability) values for the short-lived…
If dark matter (DM) is unstable, in order to be present today, its lifetime needs to be longer than the age of the Universe, t_U ~ 4 10^{17} s. It is usually assumed that if DM decays it would do it with some strength through a radiative…
We report a measurement of the positive muon lifetime to a precision of 1.0 parts per million (ppm); it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic…
We argue that because the source-detector distance of 1.8 microseconds (in natural units) for the MiniBooNE is comparable to the muon lifetime of 2.2 microseconds, and because time dilation effects are wiped out in the beam stop, the…
We revisit the constraints implied by SN 1987 A observations on the decay rate of a multi-MeV $\nu_\tau$ decaying into the visible channel $\nu_\tau \rightarrow e^+ e^- \nu_e$, if its lifetime is more than 10 {\it sec.}. We discuss its…
In the Standard Model there are several canonical examples of pure leptonic processes involving the muon, the electron and the corresponding neutrinos which are connected by the crossing symmetry: i) the decay of muon, ii) the inverse muon…
We investigate the resonant motion of neutral spin-1/2-fermions in a magnetic guide. A wealth of unitary and anti-unitary symmetries is revealed in particular giving rise to a two-fold degeneracy of the energy levels. To compute the…
The pionium decay width is evaluated in the framework of chiral perturbation theory and the relativistic bound state formalism of constraint theory. Corrections of order O(\alpha) are calculated with respect to the conventional lowest-order…
The MEG collaboration searches for the mu to e gamma decay at the muon beam line PiE5 of the Paul Scherrer Institut in Switzerland. The world best upper limit has been set to be BR(mu to e gamma) < 5.7 10^-13 at 90% C.L. analyzing a data…
Observation of the decay of muons produced in the Earth's atmosphere by cosmic ray interactions provides a graphic illustration of the counter-intuitive space-time predictions of special relativity theory. Muons at rest in the atmosphere…
We analyse the muon longitudinal polarization asymmetry \Delta_long in the decay K^+ --> \pi^+ \mu^+ mu^-. It is stressed that, since the muon helicities are not Lorentz-invariant quantities, the magnitude of \Delta_long depends in general…
The two-loop electroweak bosonic correction to the muon lifetime and the M_W-M_Z interdependece is computed using analytical methods of asymptotic expansion. Combined with previous calculations this copmletes the full two-loop correction to…
O(\alpha^2 \ln(m_\mu/m_e)) corrections to electron energy spectrum in muon decay are computed using perturbative fragmentation function approach. The magnitude of these corrections is comparable to anticipated precision of the TWIST…
A positive muon ($\mu^+$) and an electron ($e^-$) form the the hydrogen-like muonium atom ($M$=$\mu^+ e^-$). Since it consists of two leptonic particles which are according to present knowledge point-like, accurate calculations of its level…
Neutrinoless double beta decay occurs through the magnetic coupling of dimension five, $\lambda_W/m_{\nu*}$, among the excited electron neutrino $\nu^*$, electron and $W$ boson if $\nu^*$ is a massive Majorana neutrino. (\lambda_W m_W /…
We consider the $B^0_s \to \mu^{+} \mu^{-} \gamma$ effective lifetime, and the related CP-phase sensitive quantity $A_{\Delta\Gamma_s}^{\mu \mu \gamma}$, as a way to obtain qualitatively new insights on the current $B$-decay discrepancies.…
Due to large QED anomalous dimensions of the electric and magnetic dipole operators, the rate of the rare muon decay mu --> e+gamma is suppressed by the factor [ 1- 8 alpha/pi ln(Lambda/m_mu) ], independent of the physics responsible for…
Spatial and temporal variations in the electron-to-proton mass ratio, mu, and in the fine-structure constant, alpha, are predicted in non-Standard models aimed to explain the nature of dark energy. Among them the so-called chameleon-like…
The decay $\mu^-\to e^- \bar{\nu}_e\nu_\mu$ of a muon that is bound to a nucleus poses an unavoidable background for experiments such as Mu2e, COMET, and DeeMe searching for lepton-flavor-violating $\mu^-\to e^-$ conversion and thus…