Related papers: Complete O(\alpha) solution of the \mu-decay probl…
An updated measurement of alpha_s(m_tau) from ALEPH tau hadronic spectral functions is presented. We report a study of the perturbative prediction(s) showing that the fixed-order perturbation theory manifests convergence or principle…
We calculate radiative-recoil corrections of order $\alpha^2(Z\alpha)(m/M)E_F$ to hyperfine splitting in muonium generated by the diagrams with electron and muon polarization loops. These corrections are enhanced by the large logarithm of…
The analysis of the newest data on the leptonic $Z$-decays and $m_W$ appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of $2\sigma$, from their electroweak Born values,…
We calculate the rates and lepton (l) invariant mass distributions for decays of the form 0^{-+}->l^+l^-\gamma, which are important radiative corrections to the purely leptonic decays 0^{-+}->l^+l^-. Our approach uses the loop diagrams…
We present the exact O(alpha) correction to the process e+ e- -> e+ e- + gamma in the low angle luminosity regime at SLC/LEP energies. We give explicit formulas for the completely differential cross section. As an important application, we…
We discuss the decay tau^- -> nu_tau pi^- pi^0 gamma in terms of a model with the correct low-energy structure and with the relevant resonance degress of freedom. The nontrivial radiative dynamics becomes visible for large photon momenta…
The logarithmically enhanced alpha^3 ln(1/alpha) corrections to the para- and orthopositronium decay widths are calculated in the framework of dimensionally regularized nonrelativistic quantum electrodynamics.In the case of parapositronium,…
We present complete O(alpha_s^2) corrections to the decay b-->c+l+nu at the point where the invariant mass of the leptons sqrt{q^2} equals the c quark mass. We use this result, together with previously obtained corrections at the ends of…
The cross-section for ZZ->ZZ with arbitrarily polarized Z bosons is calculated within the electroweak Standard Model including the complete O(alpha) corrections. We show the numerical importance of the radiative corrections and elaborate…
We report on some technical aspects of our calculation of alpha_s^4 corrections to R(s) and the semi-leptonic tau decay width [1-3]. We discuss the inner structure of the result as well as the issue of its correctness. We demonstrate…
We calculate radiative corrections to the Lamb shift of order $\alpha^3(Z\alpha)^5m$ and radiative corrections to hyperfine splitting of order $\alpha^3(Z\alpha)E_F$ generated by the diagrams with insertions of radiative photons and…
We have applied so-called `optimised' perturbation theory to resolve the renormalisation-scale (mu) ambiguity of exact O(alpha_s^2) QCD calculations of event shape observables in e+e- --> hadrons. We fitted the optimised predictions for 15…
It is demonstrated how perturbative O(alpha_s^2) relativistic corrections to the non-relativistic stable heavy quark-antiquark production cross section in e^+e^- annihilation based on a Coulombic QCD potential can be systematically…
The QED vacuum polarization function is calculated to O(alpha^2) (next-to-leading order) accuracy in the threshold regime by using the concept of effective field theories to resum diagrams with the instantaneous Coulomb exchange of…
We compute the spin asymmetry of the muon decay through O(alpha^2) in perturbative QED. These two-loop corrections are about a factor five (twenty) smaller than the current statistical (systematic) uncertainty of the most precise…
Higher-order QED radiative corrections to muon decay spectrum are evaluated within the QED structure function approach in the next-to-leading order logarithmic approximation. New analytical results are given in the…
The effective Hamiltonian for the decay $b\to s l^+ l^-$ predicts a characteristic polarization for the final state lepton, which can serve as an important test of the underlying theory. The lepton polarization has, in addition to a…
Using computer-algebraic methods we derive compact analytical expressions for the virtual electroweak radiative corrections to polarized Compton scattering. Moreover the helicity amplitudes for double Compton scattering, which prove to be…
The electroweak $\mc O(\alpha)$ radiative corrections to the decay of the lightest MSSM Higgs boson to four leptons are presented, improved by the two-loop corrections provided by the program package FeynHiggs. We also analyze the results…
The most general Lorentz invariant spin-correlation functions for $\tau ^{-}\rightarrow \rho ^{-}\nu ,a_1^{-}\nu ,K^{*-}\nu , \pi ^{-}\nu ,K^{-}\nu $ are expressed in terms of eight semi-leptonic parameters. They are physically defined in…