Semileptonic B-meson Decays

Abstract

In this Ph.D. thesis, the exclusive semileptonic decays of B-meson within the Stan dard Model (SM) are studied. In particular the decays of B -t 7flv, B -t plv and B -t Ilv are considered. These processes provide quantitative information on the SM parameters especially the CKM matrix element lVubl and are also testing ground for non-perturbative long distance effects. These exclusive decays, although better ac cessible experimentally, but pose more problems for theoretical analysis. Thus it is important to firm up theoretical predictions in exclusive decays for precision tests of the SM. We have made such an attempt in this thesis basing our calculations on sound principles such as (i) dispersion relations (ii) chiral symmetry and quark model, (iii) Ward Identities, (iv) Vector Meson Dominance and (v) Asymptotic behaviour, of form factors as given by pQCD, where ever applicable. The main results of our work are: • The exclusive beauty semileptonic decay B -t p is studied using Ward identi ties in a general vector meson dominance framework, predicting vector meson couplings involved. The long distance contributions are discussed which results to obtain form factors and lVubl. A detailed comparison is given with other ap proaches.