Two-loop QCD penguin contribution to the width difference in B s − B ¯ s $$ {\overline{B}}_s $$ mixing

Abstract

Abstract We consider two-loop QCD corrections to the element Γ 12 q $$ {\Gamma}_{12}^q $$ of the decay matrix in B q − B ¯ q $$ {\overline{B}}_q $$ mixing, q = d, s, in the leading power of the Heavy Quark Expansion. The calculated contributions involve one current-current and one penguin operator and constitute the next step towards a theory prediction for the width difference ∆Γ s matching the precise experimental data. We present compact analytic results for all matching coefficients in an expansion in m c /m b up to second order. Our new corrections are comparable in size to the current experimental error and slightly increase ∆Γ s .

Keywords

• NLO Computations