SMEFT restrictions on exclusive b → uℓν decays

Abstract

A bstract Exclusive semileptonic b hadron decays ( b → uℓν ) serve as a sandbox for probing strong and electroweak interactions and for extracting the CKM element V ub . Instead, this work investigates their underexplored potential to reveal new short-distance physics. Utilizing SMEFT as a conduit to chart territory beyond the SM, we demonstrate that substantive new physics contributions in b → uℓν are necessarily linked to correlated effects in rare neutral-current b decays, neutral B meson mixing or high-mass Drell-Yan tails. We find that measurements of the latter processes strongly restrict the allowed deviations in the former. A complete set of tree-level mediators, originating from a perturbative ultraviolet model and matching at dimension 6, is thoroughly explored to support this assertion. As a showcase application, we examine the feasibility of a new physics interpretation of the recent tension in exclusive |V ub | extraction from B → Vℓν where V = ( ρ, ω ).