相关论文: Specific three-loop contributions to $b\to s\gamma…
We present an estimate of certain higher order corrections to the contribution of the charm triangle loop in the inclusive B -> X_s gamma decay rate, recently discussed by Voloshin. We find that these corrections are minute and hence the…
The decay B_s -> mu^+ mu^- in the Standard Model is generated by the well-known W-box and Z-penguin diagrams that give rise to an effective quark-lepton operator Q_A at low energies. We compute QCD corrections of order alpha_s^2 to its…
We explicitly compute the complete three-loop (O(g^4)) contribution to the four-point function of chiral primary current-like operators <(q)^2 q^2 (q)^2 q^2> in any finite N=2 SYM theory. The computation uses N=2 harmonic supergraphs in…
We extend existing calculations of the electromagnetic dipole operator contribution to the total decay rate and the photon energy spectrum of the decay \bar{B} -> X_s\gamma at O(\alpha_s^2) by working out the exact dependence on the charm…
We compute corrections of order $\alpha_s^3$ to the decay $b \to c \ell \bar\nu$ taking into account massive charm quarks. In the on-shell scheme large three-loop corrections are found. However, in the kinetic scheme the three-loop…
In this contribution three-loop QCD corrections to current correlators are considered. The application of the large momentum procedure, which provides a systematic expansion in $(m^2/q^2)^n$, allows the computation of terms up to $n=6$ for…
We present the two-loop master integrals relevant to the ${\mathcal O}(\alpha \alpha_s)$-corrections to the decay $H \rightarrow b \bar{b}$ through a $H t \bar{t}$-coupling. We keep the full dependence on the heavy particle masses, but…
We develop a strategy for computing the $B\to K\ell^+\ell^-$ and $\bar{B}_s\to\gamma\ell^+\ell^-$ decay amplitudes using lattice QCD (where $\ell^\pm$ are charged leptons). We focus on those terms which contain complex contributions to the…
Details of a recent calculation of O(alpha_s^2) corrections to the decay b -> c,l,nu_l, taking into account the c-quark mass, are described. Construction of the expansion in the mass ratio m_c/m_b as well as the evaluation of new four-loop…
Interference between the photonic dipole operator Q_7 and the current-current operators Q_{1,2} gives one of the most important QCD corrections to the B -> X_s gamma decay rate. So far, the O(alpha_s^2) part of this correction has been…
Penguin diagrams for decays such as $b\to (s,d)\gamma$ involve virtual loops of $u$ or other light quarks. Logarithms of the virtual quark mass could, in principle, influence the phenomenological analysis of the decay. It is thus important…
We compute the decay rate of the Standard Model Higgs boson to bottom quarks to order $\alpha\alpha_s$. We apply the optical theorem and calculate the imaginary part of three-loop corrections to the Higgs boson propagator using asymptotic…
The talk briefly reviews the current state of the art in doing multiloop QCD calculations in a completely analytic way. In particular, we discuss recent analytical calculation of 4-loop O(alpha_s**3) gluino contribution to R(s) and its…
The B_{s} --> \phi\psi decay is modeled through the inclusive b --> s\psi decay. Using the Vector Meson Dominance model, the amplitude for the chain process B_{s} --> \phi\psi --> \phi\gamma --> \gamma\gamma is estimated and it is found to…
We calculate the $O(\a_s)$ virtual corrections to the matrix element for $b \to s \gamma$, taking into account the contributions of the four-Fermi operator $O_2$ and the electromagnetic and color dipole-type operators. The results are…
We complete the calculation of the element $\Gamma_{12}^q$ of the decay matrix in $B_q-\bar{B}_q$ mixing, $q=d,s$, to order $\alpha_s$ in the leading power of the Heavy Quark Expansion. To this end we compute one- and two-loop contributions…
We consider the three-loop mixed strong-electroweak (${\mathcal{O}}(\alpha \alpha_s^2)$) corrections to the quark form factor. We compute the master integrals which are appearing in the Feynman diagrams containing a single massive boson in…
The $c \to u \gamma$ transition does not occur at the tree level in the Standard Model and is strongly GIM-suppressed at one loop. The leading QCD logarithms are known to enhance the amplitude by two orders of magnitude. We point out that…
The matrix element for the decay of orthopositronium to three photons can be expressed in terms of three independent amplitudes. We describe the analytic evaluation of these amplitudes, both to lowest order and with the inclusion of all…
The systematic investigations of the role of the virtual charm axial currents in the decay of $B$-mesons to $\eta '$ $K$ and the spin structure of the nucleon are performed. We reduce the divergence of the virtual charm axial current to a…