Related papers: Tree-level contributions to B -> Xs gamma

We evaluate the most important tree-level contributions connected with the b-> u \bar{u} d gamma transition to the inclusive radiative decay \bar{B}-> X_d gamma using fragmentation functions. In this framework the singularities arising from…

Motivated by the observation of the decay B to K* gamma by the CLEO collaboration, we have systematically analyzed the weak radiative decay Lambda_b to Lambda gamma, evaluating the confined effects of quarks in the covariant oscillator…

We present a preliminary determination of the inclusive branching fraction for the rare radiative penguin transition B -> X_{s} gamma. The measurement is based on a data sample of 60 million BB pairs collected between 1999 and 2001 with the…

We review the theoretical understanding of the branching ratio and photon-energy spectrum in B -> Xs gamma decays at next-to-leading order in QCD, including consistently the effects of Fermi motion. For the Standard Model, we obtain B(B ->…

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…

By combining a recent estimate of the total B-->X_s gamma branching fraction at O(alpha_s^2) with a detailed analysis of the effects of a cut E_gamma>1.6GeV on photon energy, a prediction for the partial B-->X_s gamma branching fraction at…

The contribution of the fourth generation quarks to the rare (B_s -> l^+ l^-) and (B_s -> l^+ l^- gamma) decays are studied. Constraints on the extended Cabibbo-Kobayashi-Maskawa matrix elements |V_{tb} V_{ts}*| and |V_{t'b} V_{t's}*| are…

I review the NLO QCD calculations of the branching ratio for B--> X_s gamma in the SM. Including the leading electromagnetic corrections, one obtaines BR(B-> X_s gamma)=(3.32 +- 0.30)*10^{-4}. Confronting theory with the newest data, an…

The charm-loop contribution to B -> Xs gamma is found to be numerically dominant and very stable under logarithmic QCD corrections. The strong enhancement of the branching ratio by QCD logarithms is mainly due to the b-quark mass evolution…

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 study the (tree-level) weak radiative decays of $B$ mesons. We present a numerical estimate for the inclusive $b \to X_c \gamma (\gamma)$ modes based on the free-quark decay. We then review what is known for the $B \to D^\star \gamma$…

Using results on soft-collinear factorization for inclusive B-meson decay distributions, a systematic study of the partial $B\to X_s\gamma$ decay rate with a cut $E_\gamma > E_0$ on photon energy is performed. For values of $E_0$ below…

Using 88.9 million BB events collected by the BaBar detector at the Y(4S), we measure the branching fraction for the radiative penguin process B -> X_s gamma from the sum of 38 exclusive final states. The inclusive branching fraction above…

A theoretical analysis of the partial inclusive B-->X_s gamma decay rate with a cut E_gamma>E_0 on photon energy must deal with short-distance contributions associated with three different mass scales: the hard scale m_b, an intermediate…

Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate standard model predictions for the inclusive…

We study the effect of anomalous Wtb couplings on the B -> Xs gamma branching ratio. The considered couplings are introduced as parts of gauge-invariant dimension-six operators that are built out of the Standard Model fields only. One-loop…

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…

We give a summary about the various contributions which have to be calculated in order to obtain the next-to-leading logarithmic result for the branching ratio $BR(B \to X_s \gamma)$. Combining all these ingredients, which were obtained by…

We study the decay B\to X_s\gamma in a minimal extension of the standard model with extra up- and down-type quarks whose left- and right-handed components are both SU(2) singlets. Constraints on the extended Cabibbo-Kobayashi-Maskawa matrix…

Two loop electroweak corrections to b --> s gamma decays are computed. Fermion and photonic loop effects are found to reduce R = BR(b --> s gamma)/BR(b --> c e nu) by 8+-2% and lead to the standard model prediction BR(B --> X_s gamma)=(3.28…