Non-leptonic B-decays in and beyond QCD Factorisation

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

Models for Light-Cone Meson Distribution Amplitudes

Leading-twist distribution amplitudes (DAs) of light mesons like pi,rho etc. describe the leading nonperturbative hadronic contributions to exclusive QCD reactions at large energy transfer, for instance electromagnetic form factors. They also enter B decay amplitudes described in QCD factorisation, in particular nonleptonic two-body decays. Being nonperturbative quantities, DAs cannot be calculated from first principles, but have to be described by models. Most models for DAs rely on a fixed order conformal expansion, which is strictly valid for large factorisation scales, but not always sufficient in phenomenological applications. We derive models for DAs that are valid to all orders in the conformal expansion and characterised by a small number of parameters which are related to experimental observables.Comment: 19 pages, 10 figure

Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software