Calculation of $B^0 o K^{*0} \mu^+ \mu^-$ and $B_s^0 o \phi \mu^+ \mu^-$ observables using form factors from lattice QCD

摘要

We calculate the differential branching fractions and angular distributionsof the rare decays $B^0 \to K^{*0} \mu^+ \mu^-$ and $B_s^0 \to \phi \mu^+\mu^-$, using for the first time form factors from unquenched lattice QCD. Wefocus on the kinematic region where the $K^*$ or $\phi$ recoils softly; therethe newly available form factors are most precise and the nonlocal matrixelements can be included via an operator product expansion. Our results for thedifferential branching fractions calculated in the Standard Model are higherthan the experimental data. We consider the possibility that the deviations arecaused by new physics, and perform a fit of the Wilson coefficients $C_9$ and$C_9^\prime$ to the experimental data for multiple $B^0 \to K^{*0} \mu^+ \mu^-$and $B_s^0 \to \phi \mu^+ \mu^-$ observables. In agreement with recent resultsfrom complementary studies, we obtain $C_9-C_9^{SM} = -1.0 \pm 0.6$ and$C_9^\prime = 1.2 \pm 1.0$, whose deviations from zero would indicate thepresence of non-standard fundamental interactions.