NLL Corrections for B-Meson Radiative Exclusive Decays

We calculate the next-to-leading corrections to the branching ratio of exclusive $B\to K^* \gamma$ decay. The renormalization scale dependence is reduced compared to the leading logarithmic result but there remains a dependence on a cutoff parameter of the hadronic model. The calculated corrections increase the predicted branching ratio by about 10%, but it remains in agreement with the experimental value.Comment: 16 pages, 8 figure

Complete NNLO QCD Analysis of B -> X_s l^+ l^- and Higher Order Electroweak Effects

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 the branching ratio in the low-q^2 region, BR_ll, by about +1% and -4%, respectively. We furthermore discuss the appropriate normalization of the electromagnetic coupling alpha and calculate the dominant higher order electroweak effects, showing that, due to accidental cancellations, they change BR_ll by only -1.5% if alpha(mu) is normalized at mu = O(m_b), while they shift it by about -8.5% if one uses a high scale normalization mu = O(M_W). The position of the zero of the forward-backward asymmetry, q_0^2, is changed by around +2%. After introducing a few additional improvements in order to reduce the theoretical error, we perform a comprehensive study of the uncertainty. We obtain BR_ll(1 GeV^2 <= q^2 <= 6 GeV^2) = (1.57 +- 0.16) x 10^-6 and q_0^2 = (3.76 +- 0.33) GeV^2 and note that the part of the uncertainty due to the b-quark mass can be easily reduced.Comment: 26 pages, 7 figures; v5: corrected normalisation in Eq. (5), numerical results unchange

Rare decays Bˉ→Xs(d)γ\bar{B}\to X_{s(d)}\gamma at the NLO

We present an independent calculation of ${\cal{O}}(\alpha_s)$ matrix elements of the QCD penguin operators for the decays $\bar{B}\to X_{s(d)}\gamma$. The Mellin-Barnes representation technique is applied for the systematic numerical evaluation of involved two-loop diagrams. The numerical effect of the calculated contributions is confirmed to be of order of 1%. We also present an updated numerical analysis for $\bar{B}\to X_{s(d)}\gamma$ decay rates.Comment: 15 pages, 4 figure

CP Asymmetry for Inclusive Decay B→Xd+γB \to X_d + \gamma in the Minimal Supersymmetric Standard Model

We study the inclusive rare decay $B\to X_d+\gamma$ in the supergravity inspired Minimal Supersymmetric Standard Model and compute the CP-asymmetry in the decay rates. We show that there exist two phenomenologically acceptable sets of SUSY parameters: for one set the CP-asymmetry has the same (positive) sign as in the Standard Model and lies in the range (5-45)% while for the other set it is negative with values within -(2-21)%.Comment: 15 pages, uses axodraw.st

Euler-Calogero-Moser system from SU(2) Yang-Mills theory

The relation between SU(2) Yang-Mills mechanics, originated from the 4-dimensional SU(2) Yang-Mills theory under the supposition of spatial homogeneity of the gauge fields, and the Euler-Calogero-Moser model is discussed in the framework of Hamiltonian reduction. Two kinds of reductions of the degrees of freedom are considered: due to the gauge invariance and due to the discrete symmetry. In the former case, it is shown that after elimination of the gauge degrees of freedom from the SU(2) Yang-Mills mechanics the resulting unconstrained system represents the ID_3 Euler-Calogero-Moser model with an external fourth-order potential. Whereas in the latter, the IA_6 Euler-Calogero-Moser model embedded in an external potential is derived whose projection onto the invariant submanifold through the discrete symmetry coincides again with the SU(2) Yang-Mills mechanics. Based on this connection, the equations of motion of the SU(2) Yang-Mills mechanics in the limit of the zero coupling constant are presented in the Lax form.Comment: Revtex, 14 pages, no figures. Abstract changed, strata analysis have been included, typos corrected, references adde