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Particles and Fields
Eur. Phys. J. C 25, 583-601 (2002)
DOI: 10.1140/epjc/s2002-01040-3

Helicity analysis of the decays $B \to K^* \ell^+ \ell^-$ and $B \to \rho \ell \nu_\ell$ in the large energy effective theory

A. Ali and A.S. Safir

Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany

(Received: 15 July 2002 / Published online: 24 September 2002 )

We calculate the independent helicity amplitudes in the decays $B \to K^* \ell^+ \ell^-$ and $B \to \rho \ell \nu_\ell$ in the so-called Large-Energy-Effective-Theory (LEET). Taking into account the dominant $O(\alpha_s)$ and SU(3) symmetry-breaking effects, we calculate various Dalitz distributions in these decays making use of the presently available data and decay form factors calculated in the QCD sum rule approach. Differential decay rates in the dilepton invariant mass and the Forward-Backward asymmetry in $B \to K^* \ell^+ \ell^-$ are worked out. We also present the decay amplitudes in the transversity basis which has been used in the analysis of data on the resonant decay $B \to K^* J/\psi (\to \ell^+ \ell^-)$. Measurements of the ratios $R_i(s) \equiv d \Gamma_{H_i}(s)(B \to K^*
\ell^+ \ell^-)/ d \Gamma_{H_i}(s)(B \to \rho \ell \nu_\ell)$ , involving the helicity amplitudes Hi(s), i=0,+1, -1, as precision tests of the standard model in semileptonic rare B-decays are emphasized. We argue that R0(s) and R-(s) can be used to determine the CKM ratio $\vert V_{ub}\vert/\vert V_{ts} \vert$ and search for new physics, where the later is illustrated by supersymmetry.

© Società Italiana di Fisica, Springer-Verlag 2002