Istituto Nazionale Fisica Nucleare

The effects of possible right-handed weak hadronic currents in rare exclusive semileptonic decays B → (K, K *)ν ¯ ν are investigated using a lattice-constrained dispersion quark model for the calculation of the relevant mesonic form factors. The results obtained for the branching ratios and the missing energy spectra are presented and the sensitivity of various observables to long-distance physics is investigated. It is shown that the asymmetry of transversely polarized K * T mesons as well as the K/K * T production ratio are only slightly sensitive to long-distance contributions and mostly governed by the relative strength and phase of right-handed currents. In particular, within the Standard Model the production of right-handed K * T mesons turns out to be largely suppressed with respect to left-handed ones, thanks to the smallness of the final to initial meson mass ratio. Therefore, the measurement of produced right-handed K * T mesons in rare B → K * ν ¯ ν decays offers a very interesting tool to investigate right-handed weak hadronic currents.