  The recent LHCb angular analysis of the exclusive decay B->K^*mu+mu- has
indicated significant deviations from the Standard Model expectations. Accurate
predictions can be achieved at large K*-meson recoil for an optimised set of
observables designed to have no sensitivity to hadronic input in the
heavy-quark limit at leading order in alpha_s. However, hadronic uncertainties
reappear through non-perturbative Lambda_QCD/m_b power corrections, which must
be assessed precisely. In the framework of QCD factorisation we present a
systematic method to include factorisable power corrections and point out that
their impact on angular observables depends on the scheme chosen to define the
soft form factors. Associated uncertainties are found to be under control,
contrary to earlier claims in the literature. We also discuss the impact of
possible non-factorisable power corrections, including an estimate of
charm-loop effects. We provide results for angular observables at large recoil
for two different sets of inputs for the form factors, spelling out the
different sources of theoretical uncertainties. Finally, we comment on a recent
proposal to explain the anomaly in B->K*mu+mu- observables through
charm-resonance effects, and we propose strategies to test this proposal
identifying observables and kinematic regions where either the charm-loop model
can be disentangled from New Physics effects or the two options leave different
imprints.
