TY - JOUR
T1 - On the impact of power corrections in the prediction of B → K* μ+μ− observables
AU - Descotes-Genon, Sébastien
AU - Hofer, Lars
AU - Matias, Joaquim
AU - Virto, Javier
PY - 2014/1/1
Y1 - 2014/1/1
N2 - © 2014, The Author(s). The recent LHCb angular analysis of the exclusive decay B → K*μ+μ− 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 αs. However, hadronic uncertainties reappear through non-perturbative ΛQCD/mb 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* μ+μ− 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.
AB - © 2014, The Author(s). The recent LHCb angular analysis of the exclusive decay B → K*μ+μ− 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 αs. However, hadronic uncertainties reappear through non-perturbative ΛQCD/mb 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* μ+μ− 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.
KW - B-Physics
KW - Rare Decays
U2 - 10.1007/JHEP12(2014)125
DO - 10.1007/JHEP12(2014)125
M3 - Article
SN - 1126-6708
VL - 2014
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
IS - 12
M1 - 125
ER -