Non-leptonic B-decays in and beyond QCD Factorisation

Abstract

This thesis examines the non-leptonic B-decays within QCD factorisation and beyond, to challenge the assumptions and limitations of the method. We analyse the treatment of the distribution amplitudes of light mesons and present a new model described by simple physical parameters. The leading twist distribution amplitudes of light mesons describe the leading non-perturbative hadronic contributions to exclusive QCD reactions at large energy transfer, for instance electromagnetic form factors. Importantly, they also enter into the two-body B decay amplitudes described by QCD factorisation. They cannot be calculated from first principles and are described by models based on a fixed-order conformal expansion, which is not always sufficient in phenomenological applications. We derive new models that are valid to all orders in the conformal expansion and characterised by a small number of parameters related to experimental observables.Motivated by the marginal agreement between the QCD factorisation results with the experimental data, in particular for $B\to \pi \pi$, we scrutinise the incalculable non-factorisable corrections to charmless non-leptonic decays. We use the available results on $B\to \pi \pi$ to extract information about the size and nature of the required non-factorisable corrections that are needed to reconcile the predictions and data. We find that the best-fit scenarios do not give reasonable agreement to $2\sigma$ until at least a 40% non-factorisable contribution is added. Finally we consider the exclusive $B\to V\gamma$ decays, where we analyse the recently updated experimental data within QCD factorisation and present constraints on generic supersymmetric models using the mass insertion approximation.

132 pages, PHD thesis; full text with high-resolution figures available from http://www.ippp.dur.ac.uk/Research/Theses/talbot.ps.gz

References in corpus (18)

• CP Violation and the CKM Matrix: Assessing the Impact of the Asymmetric B Factories
• New Results on B->pi, K, eta Decay Formfactors from Light-Cone Sum Rules
• The 2004 UTfit Collaboration Report on the Status of the Unitarity Triangle in the Standard Model
• Non-factorizable Contributions to $B\to \pi \pi$ Decays
• Semileptonic D->pi/K and B->pi/D decays in 2+1 flavor lattice QCD
• Implication of the $B\to (\rho ,\omega )\gamma$ Branching Ratios for the CKM Phenomenology
• Observation of b --> d gamma and Determination of |V_td/V_ts|
• Observation of B0->pi0pi0
• Constraining the Unitarity Triangle with B -> V gamma
• Branching Fractions and CP Asymmetries in B0 -> pi0pi0, B+ -> pi+pi0 and B+ -> K+pi0 Decays and Isospin Analysis of the B -> pipi System
• Annihilation effects in $B\to \pi \pi$ from QCD Light-Cone Sum Rules
• Models for Light-Cone Meson Distribution Amplitudes
• Improved Measurements of CP-Violating Asymmetry Amplitudes in B0 -> pi+pi- Decays
• Semileptonic B Decays with Nf=2+1 Dynamical Quarks
• Theory of Neutrinos
• Exclusive Radiative Decays of B Mesons in QCD Factorization
• Factorization fits to charmless strangeless B decays
• Radiative B Decays: Standard Candles of Flavor Physics