3 Matching Results

Search Results

Advanced search parameters have been applied.

NNLL QCD Contribution of the Electromagentic Dipole Operator to \bar B --> X_s gamma

Description: We present an independent calculation of that part of the O({alpha}{sub s}{sup 2}) contribution to dipole operator {Omicron}{sub 7}. Using a different method, we find complete agreement mass ambiguity appearing at NLL accuracy. the complete NNLL prediction of {Lambda}({bar B} {yields} X{sub s}{gamma}) which will resolve the charm quark the decay width {Lambda}({bar B} {yields} X{sub s}{gamma}) which arises from the self-interference term of the electromagnetic with a previous calculation. This NNLL contribution is an important ingredient for
Date: May 16, 2006
Creator: Asatrian, H.M.; Hovhannisyan, A.; Poghosyan, V.; Inst., /Yerevan Phys.; Ewerth, T.; Greub, C. et al.
Partner: UNT Libraries Government Documents Department

Reduction of Quark Mass Scheme Dependence in B bar -> Xs gamma at the NNLL Level

Description: The uncertainty of the theoretical prediction of the B {yields} X{sub s}{gamma} branching ratio at NLL level is dominated by the charm mass renormalization scheme ambiguity. In this paper we calculate those NNLL terms which are related to the renormalization of m{sub c}, in order to get an estimate of the corresponding uncertainty at the NNLL level. We find that these terms significantly reduce (by typically a factor of two) the error on BR(B {yields} X{sub s}{gamma}) induced by the definition of m{sub c}. Taking into account the experimental accuracy of around 10% and the future prospects of the B factories, we conclude that a NNLL calculation would increase the sensitivity of the observable B {yields} X{sub s}{gamma} to possible new degrees of freedom beyond the SM significantly.
Date: June 20, 2005
Creator: Asatrian, H.M.; Inst., /Yerevan Phys.; Greub, C.; U., /Bern; Hovhannisyan, A.; Inst., /Yerevan Phys. et al.
Partner: UNT Libraries Government Documents Department

The First Estimate of BR(\bar B to X_s\gamma) at O(\alpha_s^2)

Description: Combining our results for various {Omicron}({alpha}{sub s}{sup 2}) corrections to the weak radiative B-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find {Beta}({bar B} {yields} X{sub s}{gamma}) = (3.15 {+-} 0.23) x 10{sup -4} for E{sub {gamma}} > 1.6 GeV in the {bar B}-meson rest frame. The four types of uncertainties: non-perturbative (5%), parametric (3%), higher-order (3%) and m{sub c}-interpolation ambiguity (3%) have been added in quadrature to obtain the total error.
Date: October 24, 2006
Creator: Misiak, M.; Asatrian, H. M.; Bieri, K.; Czakon, M.; Czarnecki, A.; Ewerth, T. et al.
Partner: UNT Libraries Government Documents Department