相关论文: Estimate of BR(B -> X_s gamma) at O(alpha_s^2)

We complete the next-to-next-to-leading order QCD calculation of the branching ratio for B -> X_s l^+ l^- including recent results for the three-loop anomalous dimension matrix and two-loop matrix elements. These new contributions modify…

In this contribution the first next-to-next-to-leading order corrections to the branching ratio ${BR}(\bar{B}\to X_s\gamma)$ are discussed. This includes the completion of the matching part and the fermionic corrections to the most…

We review and update the branching ratios for the $B \to (\rho,\omega) \gamma$ decays, calculated in the QCD factorization approach in the next-to-leading order (NLO) in the strong coupling $\alpha_s$ and to leading power in $\Lambda_{\rm…

Working in a perturbative QCD model approach, we obtain the essential form factor of the radiative transition $B \rightarrow V^{*} \gamma$ and estimate the branching ratio $BR(B \rightarrow K^{*} \gamma)$. The results are determined by a…

The calculation of the $O(\a_s)$ virtual corrections to the matrix element of the inclusive decay $b \to s \gamma$ is reported. These contributions drastically reduce the large renormalization scale dependence of the leading logarithmic…

We present upgraded theoretical predictions for inclusive and exclusive radiative decays of {\it B} mesons. Our results include those next-to-leading order corrections that have already been computed. Our best estimates in the Standard…

Using results on soft-collinear factorization for inclusive B-meson decay distributions, a systematic study of the partial B->Xs+gamma decay rate with a cut E_gamma<E_0 on photon energy is performed. For values E_0<1.9 GeV the rate can be…

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 calculate the branching ratios of $B\to K_1\gamma$ at next-to-leading order (NLO) of $\alpha_s$ where $K_1$ is the orbitally excited axial vector meson. The NLO decay amplitude is divided into the vertex correction and the hard spectator…

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…

The B -> X_s gamma branching ratio is currently measured with around 5% accuracy. Further improvement is expected from Belle II. To match such a precision on the theoretical side, evaluation of O(alpha_s^2) corrections to the partonic decay…

We have investigated the exclusive, radiative B-meson decay to K_2^*(1430) in 88.5 * 10^6 BBbar events. We present a preliminary measurement of the branching fractions BR(B->K^*_2(1430)^0 gamma) = (1.22+-0.25+-0.11) * 10^{-5} and…

We present details of our evaluation of the NNLO QCD corrections to BR(B -> X_s gamma) in the heavy charm limit m_c >> m_b/2. Results of this calculation have been essential for estimating O(alpha_s^2) effects in this branching ratio via…

We studied radiative B meson decays with the Belle detector. We measured the following branching fractions; Br(B->K*0(892)\gamma) = (49.6 \pm 6.7 \pm 4.5) x 10^{-6}, Br(B->K*+(892)\gamma) = (38.9 \pm 9.3 \pm 4.1) x 10^{-6}, Br(B->Xs\gamma)…

We calculate the branching ratio for B -> J/psi + anything, within the color-singlet approximation for J/psi production, but including perturbative QCD corrections beyond the leading logarithm approximation. Such higher order corrections…

We have measured the branching fraction of the inclusive radiative B meson decay B --> X(s) gamma to be Br(B->X(s)gamma)=(3.36 +/- 0.53(stat) +/- 0.42(sys) +0.50-0.54(th)) x 10^{-4}. The result is based on a sample of 6.07 x 10^6 BBbar…

We present the QCD corrections to the matching conditions of the Delta B =1 magnetic and chromo-magnetic operators in the Standard Model and in two-Higgs doublet models. We use an off-shell matching procedure which allows us to perform the…

We combine recent progress in measuring the branching ratio of the decay B->X_d gamma$ with the discovery that hadronic uncertainties in the CP-averaged branching ratio drop out to a large extent. Implications of these improvements on the…

It is shown that the inclusive rate of the rare weak radiative decays $B \to X_s \gamma$ contains a series of nonperturbative corrections, whose `short distance' scale is set by $m_c^{-1}$, rather than by $m_b^{- 1}$. The first correction…

We analyze uncertainties in the theoretical prediction for the inclusive branching ratio $BR[B \rightarrow X_s \gamma]$. We find that the dominant uncertainty in the leading order expression comes from its $\mu$-dependence. We discuss a…