Measurement of angular asymmetries in the decays B →k∗+

Abstract

We study the lepton forward-backward asymmetry A F B and the longitudinal K ∗ polarization F L , as well as an observable P 2 derived from them, in the rare decays B → K ∗ ℓ + ℓ − , where ℓ + ℓ − is either e + e − or μ + μ − , using the full sample of 471 million B ¯ B events collected at the Υ ( 4 S ) resonance with the BABAR, detector at the PEP-II e + e − collider. We separately fit and report results for the K * 0 ( 892 ) ℓ + ℓ − and K * + ( 892 ) ℓ + ℓ − final states, as well as their combination K ∗ ℓ + ℓ − , in five disjoint dilepton mass-squared bins. An angular analysis of B + → K * + ℓ + ℓ − decays is presented here for the first time.