相关论文: Muon Decay Spectrum: Leading Logarithmic Approxima…
When a particle decays in an external field, the energy spectrum of the products is smeared. We derive an analytical expression for the shape function accounting for the motion of the decaying particle and the final state interactions. We…
Radiative muon and tau lepton decays are described within the model-independent approach with the help of generalized Michel parameters. The exact dependence on charged lepton masses is taken into account. The results are relevant for…
We show theoretically that the angular distribution of decay rate of muon can be changed dramatically by embedding the decaying muon in a strong linearly polarized laser field. Evaluating the S-matrix elements taking all electronic…
We have noted that the electron spectrum of muon decay in the leading logarithmic approximation calculated in two lowest orders of the perturbation theory in the paper of Berman (1958), can be reproduced by the parton language. This fact…
The FAC, PMS, and BLM optimization methods are applied to the QED corrections to the muon lifetime in the Fermi V-A theory. The FAC and PMS scales are close to m_e, while the BLM scale nearly concides with the geometric average \sqrt{m_e…
The B -> X_s l+ l- decay rate is known at the next-to-next-to-leading order in QCD. It is proportional to alpha_em (mu)^2 and has a +- 4% scale uncertainty before including the O(alpha_em log(M_W^2/m_b^2)) electromagnetic corrections. We…
We have performed a global analysis of muon decay measurements to establish model-independent limits on the space-time structure of the muon decay matrix element. We find limits on the scalar, vector and tensor coupling of right- and…
Calculation of higher-order radiative corrections to unpolarized muon decay spectrum is discussed. Results for the orders $\mathcal{O}(\alpha^2 L)$, $\mathcal{O}(\alpha^3 L^3)$ and $\mathcal{O}(\alpha^3 L^2)$ are presented.
In this article two-loop QED corrections to the muon decay and corrections of order $\alpha_s^2$ to the semileptonic decay of the bottom quark are considered. We compute the imaginary part of the four-loop diagrams contributing to the…
We report on the calculation of the two-loop electroweak, two-photon mediated short-distance dispersive K_L \to \mu^+\mu^- decay amplitude. QCD corrections change the sign of this contribution and reduce it by an order of magnitude. The…
The $O(\alpha^2\log(Q^2/m_e^2))$ leptonic QED corrections to unpolarized deeply inelastic electron-nucleon scattering are calculated in the mixed variables.
We estimate sensitivity coefficients Q_\mu to variation of the electron-to-proton mass ratio \mu for microwave transitions in partly deuterated ammonia NH2D and ND2H. Because of the mixing between rotational and inversion degrees of freedom…
The calculation of the $O(N_f\alpha^2)$ corrections to muon decay is described. These are the 2-loop diagrams containing a massless fermion loop and they form an important gauge-invariant subclass. It is shown that all such diagrams can be…
We model-independently analyze the angular distributions of B -> K ll decays, l = e, mu, for low dilepton mass using QCD factorization. Besides the decay rate, we study the forward-backward asymmetry A_FB^l and a further observable, F_H^l,…
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…
The electroweak corrections at the order of $O(\alpha_{ew}m_{t(b)}^2/m_W^2)$ to the partial widths of the $\tilde{t}_2 \to \tilde{g} + t$ and $\tilde{g} \to \tilde{t}_1 + \bar{t} $ decays (depending on the masses of the particles involved)…
Quantum chromodynamics (QCD) effects in the semileptonic decay b -> c l nu are evaluated to the second order in the coupling constant, O(alpha_s^2), and to several orders in the expansion in quark masses, m_c/m_b. Corrections are calculated…
The TWIST Collaboration has measured the Michel parameter $\rho$ in normal muon decay, $\mu^+ \to e^+ \nu_e \bar{\nu}_{\mu}$. In the Standard Model, $\rho$ = 3/4. Deviations from this value require mixing of left- and right-handed muon and…
An analytical expression for the spin-averaged amplitude squared of the rare muon decay $\mu^+ \to e^+e^-e^+\nu_e\bar{\nu_\mu}$ is calculated. Monte Carlo phase space simulation using the analytical expression for the amplitude has been…
Radiative muon decay in the kinematics similar to the neutrinoless decay $\mu\to e\gamma$ is considered. Radiative corrections due to 1-loop virtual photons and emission of additional soft or hard photons are taken into account. Analytical…