Zooming in on $B\to K^{\ast }\ell \ell$ decays at low recoil

Abstract

We analyse $B\to K^{\ast }\ell \ell$ decays in the region of low hadronic recoil, where an operator product expansion (OPE) in $1/m_b$ applies. Using a local model for charm contributions based on $e^{+}{e}^{-}\to hadrons$ against the OPE provides a data-driven method to access the limitations to the OPE's accuracy related to binnings in the dilepton mass. Model-independent fits to $B\to K^{\ast }\mu \mu$ low recoil angular observables exhibit presently only small sensitivity to different charm models. They give similar results as the fits based on the OPE, and are in agreement with the standard model, but leave also room for new physics. Measurements with resolution small enough to probe charm resonances would be desirable.

18 pages, v2: references and clarifications added, conclusions unchanged, matches published version

References in corpus (4)

• Measurement of the Differential Branching Fraction and Forward-Backword Asymmetry for B->K(*)l+l-
• Global fits to b -> s ll data and signs for lepton non-universality
• New physics reach of the decay mode $\bar{B}\to {\bar{K}}^{\ast 0}{\ell }^{+}{\ell }^{-}$
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• Rare FCNC radiative leptonic $B_{s,d}\to \gamma l^{+}{l}^{-}$ decays in the Standard Model
• Endpoint Relations for Baryons
• Status of rare exclusive $B$ meson decays in 2018
• Manifestation of Lepton Interaction Nonuniversality in Spontaneously Violated Mirror Symmetry
• Long-distance QCD effects in FCNC $B\to \gamma l^{+}{l}^{-}$ decays