A new way to search for right-handed currents in semileptonic B→ρℓν‾ decay

AbstractThere exist a long standing tension among determinations of the CKM matrix element |Vub| from various (semi)leptonic B decay channels with varying significance of up to ∼3σ. An interesting possibility to ease this tension is to allow for a right-handed contribution to the standard model left-handed weak current mediating the b→u quark decay. Current bounds on such a contribution are fairly weak. We propose a new way to search for such a right-handed current in semileptonic B→ρ meson decays. We describe a new variable that we propose, and discuss the theoretical uncertainties. Especially we investigate the uncertainties and their correlations among all contributing form factors with the assumed z-expansion for its shape, valid over the whole q2 range. Then we study the achievable sensitivity both from the available Babar and Belle data sets, as well as from an anticipated 50 ab−1 at Belle II