Probing new physics via the transverse amplitudes of B0→K *0(→K-π+)l+l- at large recoil

Frank Krüger, Joaquim Matias

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We perform an analysis of the K* polarization states in the exclusive B meson decay B0→K*0(→K-π+)l+l- (l=e,μ,τ) in the low dilepton mass region, where the final vector meson has a large energy. Working in the transversity basis, we study various observables that involve the K* spin amplitudes A, A, A0 by exploiting the heavy-to-light form-factor relations in the heavy quark and large-EK* limit. We find that at leading order in 1/mb and αs the form-factor dependence of the asymmetries that involve transversely polarized K* completely drops out. At next-to-leading logarithmic order, including factorizable and nonfactorizable corrections, the theoretical errors for the transverse asymmetries turn out to be small in the standard model (SM). Integrating over the lower part of the dimuon mass region, and varying the theoretical input parameters, the SM predicts AT(1)=0.9986±0.0002 and AT(2)=-0.043±0.003. In addition, the longitudinal and transverse polarization fractions are found to be (69±3)% and (31±3)%, respectively, so that ΓL/ΓT=2. 23±0.31. Beyond the SM, we focus on new physics that mainly gives sizable contributions to the coefficients C7eff(′) of the electromagnetic dipole operators. Taking into account experimental data on rare B decays, we find large effects of new physics in the transverse asymmetries. Furthermore, we show that a measurement of longitudinal and transverse polarization fractions will provide complementary information on physics beyond the SM. © 2005 The American Physical Society.
Original languageEnglish
Article number094009
Pages (from-to)1-3
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Publication statusPublished - 1 May 2005


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