Meson distribution amplitudes: applications to weak radiative B decays and в transition form factors

Abstract

This thesis examines the applications and determinations of meson light-cone distribution amplitudes, which enter the theoretical description of exclusive processes at large moment urn transfer. The investigation of such processes, in the context of в physics, provides one with a rich and extensive way of determining the Standard Model parameters of the CKM matrix, which are essential in describing CP violation, and searching for tell-tale signs of new physics beyond the Standard Model. We investigate the twist-2 and twist-3 distribution amplitudes of vector mesons and fully examine SU(3)(_F)-breaking effects and include leading G-parity violating terms. We use the conformal expansion allowing the distribution amplitudes to be described by a set of non-perturbative hadronic parameters which is reduced by invoking the QCD equation of motion to find various interrelations between the distribution amplitudes. Numerical values of the leading non-perturbative hadronie parameters are determined from QCD sum rules. The new distribution amplitude results find direct application in the radiative B decays to light vector mesons B → Vγ. We examine the phenomenologically most important observables in this decay mode using the formalism of QCD factorisation in which the distribution amplitudes play a vital role. We also include long-distance photon emission and soft quark loop effects, which formally lie outside the QCD factorisation formalism. The analysis encompasses all the relevant modes, that is B(_u),(_d)→(_p),(_w),K* and B(_s) → φ,K*.We also calculate the B → n(^1) transition form factor using QCD sum rules on the light- cone. The method relies on the collinear factorisation of the QCD dynamics into a pertur- batively calculable hard-scattering kernel and the non-perturbative universal distribution amplitudes. We include the singlet contribution originating from the U(1)a anomaly and bring the calculation consistently within the n-n(^1) mixing framework.