相关论文: Large mass expansion in two-loop QCD corrections o…
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,…
We present the analytic calculation of the two-loop QCD corrections to the decay width of a Higgs boson into a photon and a $Z$ boson. The calculation is carried out using integration-by-parts identities for the reduction to master…
We present the QCD and QED corrections to the fermion-loop contributions to light-by-light scattering, gamma gamma to gamma gamma, in the ultrarelativistic limit where the kinematic invariants are much larger than the masses of the charged…
Using dimensional regularization for both infrared and ultraviolet divergences, we confirm that the QCD corrections to the decay width $\Gamma(t\to H^+b)$ are equal to those to $\Gamma(t\to W^+b)$ in the limit of a large $t$ quark mass.
An analytic formula for the two-loop QCD correction of the decay H --> 2 gamma is presented. To evaluate all master integrals a `Risch-like' algorithm was exploited.
We present the analytical $\alpha_{s}^3$ correction to the $Z^{0}$ decay rate into hadrons. We calculate this correction up to (and including) terms of the order $(m_Z^2/m_{top}^2)^3$ in the large top quark mass expansion. We rely on the…
Two-loop QED corrections to the decay rate of parapositronium (p-Ps) into two photons are presented. We find Gamma(p-Ps --> 2 photons) = 7989.64(2)/microsec. The non-logarithmic O(alpha^2) corrections turn out to be small, contrary to some…
We consider two-loop QCD corrections to the element $\Gamma_{12}^q$ of the decay matrix in $B_q-\bar{B}_q$ mixing, $q=d,s$, in the leading power of the Heavy Quark Expansion. The calculated contributions involve one current-current and one…
We present O(alpha_s^2) corrections to the decay t-->bW in the limit of a very large top quark mass, m_t >> m_W. We find that the O(alpha_s^2) effects decrease the top quark decay width Gamma_t by about 2%: Gamma_t =…
We reinvestigate the leading QCD corrections to the radiative decay $b \to s \gamma for supersymmetric extensions of the Standard Model. Although the major contributions to the corrections originate from the running of the effective…
We compute the O(alpha_s^2) correction to the decay rate eta_c --> gamma gamma and discuss its implications for precision quarkonium physics. We study the suitability of the ratio Gamma(J/psi --> e+e-)/Gamma(eta_c --> gamma gamma), in which…
The complete set of two-loop electroweak corrections to the decay width of the Higgs boson into two photons is presented. Two-loop contributions involving weak bosons and the top quark are computed in terms of an expansion in the Higgs…
We present a complete calculation of the Leading Order QCD corrections to the quark level decay amplitude for b -> s gamma gamma and study their relevance for both the inclusive branching ratio BR(B -> X_s gamma gamma) and for the exclusive…
The partial decay rate $\Gamma(Z\to b\bar{b})$ is significantly influenced by the mass of the top quark due to electroweak radiative corrections. The leading $\sim m_t^2$ and the next-to-leading contribution $\sim \ln m_t^2$ are known to be…
QCD corrections to the electroweak one-loop result for the partial width $\Gamma(H\rightarrow b\bar{b})$ are studied. For the decay channel into bottom quarks the rate is affected by a virtual top quark through electroweak interactions. The…
We compute the \alpha_s^2\beta_0 part of the two-loop QCD corrections to the charged lepton spectrum in b \to c \ell \bar\nu_\ell decays and find them to be about 50\% of the first order corrections at all lepton energies, except those…
We present the result for the three-loop singlet QCD corrections to the decay of a Higgs boson into two photons and improve the calculation for the non-singlet case. With the new result presented, the decay width Gamma(H -> \gamma \gamma)…
We present a next-to-leading-order (NLO) analysis of the rare radiative decay $\eta_b \to J/\psi\gamma$, a flavor-changing transition between bottomonium and charmonium, within the framework of non-relativistic QCD (NRQCD). We…
By analyzing existing data on pseudoscalar charmonium decays, we obtain the ratio of the branching fractions of $\eta_c(2S)$ and $\eta_c$ decays into ten different final states with light hadrons. For the first time, we test the two…
Order $\alpha^2$ corrections to the decay rate of parapositronium are calculated. A QED scattering calculation of the amplitude for electron-positron annihilation into two photons at threshold is combined with the technique of effective…