Related papers: Techniques for computing two-loop QCD corrections …
The perturbative QCD corrections to the nonleptonic decay rate of the $b$ quark are discussed. By considering the limit where the final charmed quarks are slow, it is argued that the coefficients of the $\alpha_s^2$ terms, corresponding to…
We calculate the radiative corrections to the nonleptonic inclusive B decay mode $b\to c ud$ taking into account the charm quark mass. The corrections increase the decay rate by (4--8)\%, depending on the renormalization point. Using these…
We discuss the epsilon-method as used in various recent QED bound-state calculations by considering mathematical model examples. Recently obtained results for higher-order self-energy binding corrections at the two-loop level are reviewed.…
We present a QCD analysis of heavy quark mesons focussing on the B -> D* formfactor at zero recoil, F_D*(1). An advanced treatment of the perturbative corrections in the Wilsonian approach is presented. We estimate the higher-order power…
It is shown that up to an over all scale the lowest-order QCD corrections to $t\to H^+b$ and to $t\to W^+b$ are the same in the heavy top limit. Asymptotically, they are given by $-{4\alpha_s\over 3\pi}[{\pi^2\over 3}-{5\over 4}]$,…
We present the full ${{\cal O}}(\alpha)$ electroweak radiative corrections to associated Higgs top pair production in $e^+e^-$ collisions. We combine these results with a new calculation of the full one-loop QCD corrections. The computation…
The flavor-changing electromagnetic dipole operator O_7 gives the dominant contribution to the B -> Xs gamma decay rate. We calculate two-loop QCD corrections to its matrix element together with the corresponding bremsstrahlung…
The results of perturbative QCD evaluation of the ~m_f^2/M_Z^2 contributions to the decay rates in Z--->bb and Z--->hadrons for the quark masses m_f << M_Z are presented. The recent results due to the combination of renormalization group…
We calculate the Yukawa corrections of order ${\cal O}(\alpha_{ew}m_{t(b)}^2/m_W^2)$, ${\cal O}(\alpha_{ew}m_{t(b)}^3/m_W^3)$ and ${\cal O}(\alpha_{ew}m_{t(b)}^4/m_W^4)$ to the widths of the decays $\tilde t_2\to \tilde t_1 + (h^0,H^0,A^0)$…
The differential decay spectrum $d\Gamma/dE_e dq^2$ for the semileptonic decay of an unpolarized hadron containing a b-quark, and the decay spectrum $d\Gamma/dE_e dq^2 d\!\cos\theta$ for polarized $\Lambda_b$ decay are computed to second…
Quark mass effects in ${\cal O}(\alpha_s^2)$ QCD corrections to the decay rates of intermediate Higgs bosons are studied. The total hadronic rate and the partial decay rate into bottom quarks are analyzed for the Standard (scalar) Higgs…
Low- and intermediate mass Higgs bosons decay preferably into fermion pairs. The one-loop electroweak corrections to the respective decay rates are dominated by a flavour-independent term of ${\cal O}(G_Fm_t^2)$. We calculate the two-loop…
We discuss the computation of QCD virtual corrections to the top production and decay process at linear colliders. The double pole approximation (DPA) is used, and we comment on similarities and differences between our results and results…
We propose to resum exactly any number of one-loop vacuum polarization insertions into the scale of the coupling of lowest order radiative corrections. This makes maximal use of the information contained in one-loop perturbative corrections…
A model independent approach based on a generalization of the operator product expansion is used to describe semileptonic decays of heavy flavors. In the first part of the dissertation we calculate differential distributions in the…
The order alpha_s^2 contribution to the inclusive semileptonic decay width of a b quark \Gamma(b -> X_u e \bar{\nu}_e) is calculated analytically for zero mass u quarks.
Non-singlet ${\cal{O}}(\alpha_s^2)$ corrections from light quarks are calculated analytically for the massive quark-antiquark pair production rates through the vector, axial-vector, scalar and pseudoscalar currents for all energies above…
In this paper the complete two-loop corrections to the Higgs-boson decay, H -> gamma gamma, are presented. The evaluations of both QCD and electroweak corrections are based on a numerical approach. The results cover all kinematical regions,…
A detailed standard model (SM) calculation of the O(alpha_s) virtual corrections to the decay width for b -> s g is presented (g denotes a gluon). Also the complete expressions for the corresponding bremsstrahlung corrections are given.…
We give a more complete calculation of $b \to s e^+e^- $ decay including leading log QCD corrections from $m_{top}$ to $M_W$ in addition to corrections from $M_{W}$ to $m_b$. The differential decay rate is found to be slightly suppressed…