Anatomy of the B-meson Light-Cone Distribution Amplitude

In the Standard Model of particle physics, the strong dynamics of hadronic particles such as the B meson are governed by Quantum Chromodynamics (QCD). Currently, there exists no single method capable of accurately predicting all phenomena associated with QCD. Rather, various specialized methods have emerged to address specific phenomena. Among these approaches, QCD Factorization and QCD Light-Cone Sum Rules are used for exclusive, energetic B decays. Therein, the B-meson Light-Cone Distribution Amplitudes (LCDAs) systematically represent the internal structure of the B meson, and as such, the LCDAs are (presently) inaccessible from first principles. In this thesis, we develop a new systematic framework for phenomenological analyses, focusing on the leading-twist B-meson LCDA which leads to the dominant contribution in predictions. Our framework allows for the integration of various theoretical and experimental constraints to infer the LCDA and derive predictions. While models have been used for the same purpose, our approach makes systematic uncertainties quantifiable and provides greater transparency in the implementation of constraints.
We derive a new systematic parametrization of the leading-twist B-meson LCDA that fulfills established mathematical properties and satisfies a parameter bound to address the issue of truncation in the expansion. We discuss certain practical aspects, such as renormalization group evolution, the implementation of the known short-distance behavior as a fit constraint, and more. In addition, we update the known short-distance behavior with the effect of a non-zero spectator quark mass to improve the effectiveness of our approach for applications with the Bs meson. For this purpose, we perform a generic matching calculation, which further yields a new result for the short-distance behavior of the subleading 2-particle LCDA. To demonstrate the practical utility of our framework, we perform a detailed analysis of the decay mode B meson to photon, lepton, and neutrino, which serves as a benchmark for probing the leading-twist B-meson LCDA. To that end, we extended the EOS software with experimental observables of this decay and pseudo-observables to accommodate the theoretical short-distance constraint. This enabled a proof-of-concept study using mock data and the Bayesian analysis tools in EOS which underscores the utility of the measurement of this decay mode and further demonstrates the effectiveness of the parameter bound in managing truncation errors. This analysis highlights the significant potential of our approach for future research.