Two-Loop Bosonic Electroweak Corrections to the Muon Lifetime and M_Z-M_W Interdependence

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 $\Delta r$ in the Standard Model. The shift to the prediction of W-boson mass due to two-loop bosonic corrections does not exceed 1 MeV for the range of the Higgs mass from 100 to 1000 GeV.Comment: 8 pp, 3 figs, LaTeX, replaced with journal versio

Single-scale diagrams and multiple binomial sums

The $\epsilon$-expansion of several two-loop self-energy diagrams with different thresholds and one mass are calculated. On-shell results are reduced to multiple binomial sums which values are presented in analytical form.Comment: 10 pp LaTeX, misprints in app. A and minor misprints in the text correcte

The Differential equation method: calculation of vertex-type diagrams with one non-zero mass

The differential equation method is applied to evaluate analytically two-loop vertex Feynman diagrams. Three on-shell infrared divergent planar two-loop diagrams with zero thresholds contributing to the processes Z --> bb bar (for zero b mass) and/or H --> gg are calculated in order to demonstrate a new application of this method.Comment: 12 pages, LATEX, uses axodray.st

Two-loop O(as^2) MSSM corrections to the pole masses of heavy quarks

We present the results for two-loop MSSM corrections to the relation between pole and running masses of heavy quarks up to the order O(as^2). The running masses are defined in the DR scheme, usually used in multiloop calculations in supersymmetric theories. The analysis of the value of these corrections in different regions of the parameter space is provided.Comment: 25 pages, 10 figures, LaTeX2e file; minor changes, files mb.res, mt.res replaced by new one

Three-loop massive tadpoles and polylogarithms through weight six

We evaluate the three-loop massive vacuum bubble diagrams in terms of polylogarithms up to weight six. We also construct the basis of irrational constants being harmonic polylgarithms of arguments $e^{k i \pi/3}$.Comment: 26 pages, 4 ancillary files, v3: version published in JHEP: minor additions, file with results for massive three-loop form-factor integrals adde

The γ∗γ∗→ηc\gamma^* \gamma^*\to\eta_c transition form factor

We study the $\gamma^* \gamma^*\to\eta_c$ transition form factor, $F_{\eta_c\gamma\gamma}(Q_1^2,Q_2^2),$ with the local-duality (LD) version of QCD sum rules. We analyse the extraction of this quantity from two different correlators, and $,$ with $P,$ $A,$ and $V$ being the pseudoscalar, axial-vector, and vector currents, respectively. The QCD factorization theorem for $F_{\eta_c\gamma\gamma}(Q_1^2,Q_2^2)$ allows us to fix the effective continuum thresholds for the and $$ correlators at large values of $Q^2=Q_2^2$ and some fixed value of $\beta\equiv Q_1^2/Q_2^2$. We give arguments that, in the region $Q^2\ge10$--$15 GeV^2$, the effective threshold should be close to its asymptotic value such that the LD sum rule provides reliable predictions for $F_{\eta_c\gamma\gamma}(Q_1^2,Q_2^2).$ We show that, for the experimentally relevant kinematics of one real and one virtual photon, the result of the LD sum rule for $F_{\eta_c\gamma}(Q^2)\equiv F_{\eta_c\gamma\gamma}(0,Q^2)$ may be well approximated by the simple monopole formula $F_{\eta_c\gamma}(Q^2)={2e_c^2N_cf_P}(M_V^2+Q^2)^{-1},$ where $f_P$ is the $\eta_c$ decay constant, $e^2_c$ is the $c$-quark charge, and the parameter $M_V$ lies in the mass range of the lowest $\bar cc$ vector states.Comment: 9 page