Light-front quark model analysis of rare [Formula Presented] decays

Using the light-front quark model, we calculate the transition form factors, decay rates, and longitudinal lepton polarization asymmetries for the exclusive rare (Formula presented) decays within the standard model. Evaluating the timelike form factors, we use the analytic continuation method in the (Formula presented) frame to obtain the form factors (Formula presented) and (Formula presented) which are free from the zero mode. The form factor (Formula presented) which is not free from the zero mode in the (Formula presented) frame and contaminated by the higher (or nonvalence) Fock states in the (Formula presented) frame is obtained from an effective treatment for handling the nonvalence contribution based on the Bethe-Salpeter formalism. The covariance (i.e., frame independence) of our model calculation is discussed. We obtain the branching ratios for (Formula presented) as (Formula presented) for (Formula presented) and (Formula presented) for (Formula presented).