Precise predictions for B -> Xs l+ l- in the large q^2 region

Understand

The inclusive B -> Xs l+ l- decay rate in the large q^2 region (q^2 > m_{\psi'}^2) receives significant nonperturbative corrections.

• The resulting uncertainties can be drastically reduced by normalizing the rate to the B -> Xu l nu rate with the same q^2 cut, which allows for much improved tests of short distance physics.
• We calculate this ratio, including the order 1/m_b^3 nonperturbative corrections and the analytically known NNLO perturbative corrections.
• Since in the large q^2 region an inclusive measurement may be feasible via a sum over exclusive states, our results could be useful for measurements at LHCb and possibly for studies of B -> Xd l+ l-.