B semileptonic moments at NNLO

The calculation of the moments in inclusive B meson semileptonic decays is upgraded to O(alphas^2). The first three moments of the lepton energy and invariant hadronic mass distributions are computed for arbitrary cuts on the lepton energy and in various renormalization schemes, finding in general small deviations from the O(alphas^2 beta0) calculation. I also review the relation between MSbar and kinetic heavy quark masses.Comment: 28 pages, 9 figure

Precision Electroweak Measurements Circa 2002

Present global fits to electroweak data are characterized by two results that differ from Standard Model expectations by about 3 sigma, the NuTeV measurement of sin^2theta_W and the FB b quark asymmetries measured at LEP. I review possible SM and new physics explanations of these anomalies and the implications for the indirect determination of the Higgs mass.Comment: 6 pages, 2 figures, talk at ICHEP, Amsterdam, 24-31 July 200

Complete electroweak matching for radiative B decays

We compute the complete two-loop O(alpha) Wilson coefficients relevant for radiative decays of the B meson in the SM. This is a necessary step in the calculation of the O(alpha alpha_s^n ln^n m_b/M_W) corrections and improves on our previous analysis of electroweak effects in B -> X_s gamma. We describe in detail several interesting technical aspects of the calculation and include all dominant QED matrix elements. In our final result, we neglect only terms originated from the unknown O(alpha alpha_s) evolution of the Wilson coefficients and some suppressed two-loop matrix elements. Due to the compensation among different effects, we find that non-trivial electroweak corrections decrease the branching ratio by about 3.6% for a light Higgs boson, very close to our previous result. The corresponding up-to-date SM prediction for the branching ratio with E_gamma > 1.6 GeV is (3.61 +- 0.30) x 10^-4.Comment: 20 pages, 2 figures, uses amssymb.sty, amsmath.sty and feynarts.sty. Minor change

Electroweak effects in radiative B decays

We compute the two-loop electroweak corrections to the radiative decays of the B meson in the SM. Electroweak effects reduce the Wilson coefficient C_7^eff(mw) by 2.6% for a light Higgs boson of about 100 GeV and are less important for a heavier Higgs. The leading term of a heavy top expansion of our result differs from the one obtained in the gaugeless approximation where only top quark Yukawa couplings are considered: we discuss the origin of the discrepancy and provide a criterion for the validity of the gaugeless approximation. As a byproduct of the calculation we also obtain the O(alpha) corrections to the Wilson coefficient of the four-fermion operator Q_2. A careful analysis of the interplay between electroweak and QCD effects leads to an overall 2% reduction of the total branching ratio for B -> X_s gamma due to purely electroweak corrections. For a light Higgs boson, the up-to-date SM prediction is BR_gamma=3.29 10^-4.Comment: 15 pages, 3 figure

Revisiting B→DℓνB\to D \ell \nu

We re-examine the determination of $|V_{cb}|$ from $B\to D \ell \nu$ in view of recent experimental and theoretical progress, discussing the parameterization of the form factors and studying the role played by the unitarity constraints. Our fit to experimental and lattice results for $B\to D \ell \nu$ gives $|V_{cb}|=40.49(97)\ 10^{-3}$ and to $R(D)= 0.299(3)$.Comment: 19 pages, 2 figures; v2: BCL fits, various clarifications and refs adde