Radiative and Semileptonic B Decays Involving the Tensor Meson K_2^*(1430) in the Standard Model and Beyond

Abstract

We study semileptonic and radiative B decays involving the strange tensor meson K_2^*(1430) in the final state. Using the large energy effective theory (LEET) techniques, we formulate the B \to K_2^* transition form factors in large recoil region. All the form factors can be parametrized in terms of two independent LEET parameters \zeta_\perp and \zeta_\parallel. The magnitude of \zeta_\perp is estimated from the data for Br(B \to K_2^*(1430)\gamma). Assuming a dipole q^2-dependence for the LEET parameters and \zeta_\parallel/\zeta_\perp = 1.0 \pm 0.2, we investigate the decays B \to K_2^* \ell^+ \ell^- and B \to K_2^* \nu \bar{\nu}, where the contributions due to $\zeta_\parallel are suppressed by m_{K_2^*}/m_B. For the B \to K_2^* \ell^+ \ell^- decay, in the large recoil region where the hadronic uncertainties are considerably reduced, the longitudinal distribution d F_L/ds is reduced by 20-30 % due to the flipped sign of c_7^eff compared with the standard model result. Moreover, the forward-backward asymmetry zero is about 3.4 GeV^2 in the standard model, but changing the sign of c_7^eff yields a positive asymmetry for all values of the invariant mass of the lepton pair. We calculate the branching fraction for B \to K_2^* \nu \bar{\nu} in the standard model. Our result exhibits the impressed resemblance between B \to K_2^*(1430) \ell^+\ell^-, \nu \bar{\nu} and B \to K^*(892) \ell^+ \ell^-, \nu\bar{\nu}.