Aspects of hadronic B decays in and beyond the standard model

In this thesis we address various issues of hadronic B decays, in the Standard Model and beyond. Concerning the first aspect, we focus on the problem of understanding better low energy strong interactions in these decays. We consider in particular B decays into a charmonium state and a light meson. We develop a complete treatment of low energy QCD interaction in the context of QCD factorization, treating the charmonia as non-relativistic bound states. This allows us to demonstrate that, in the heavy-quark limit, a perturbative treatment of these decays is possible, even in case of decays into P-waves, which were found to be non-factorizing in previous studies. We achieve this, including in the analysis the bound state scales of charmonium, which in turn requires to consider charmonium production through colour-octet operators. Although there are very large uncertainties, we find reasonable parameter choices, where the main features of the data - large corrections to (naive) factorization and suppression of the chi_{c2} and h_c final states - are reproduced though the suppression of chi_{c2} is not as strong as seen in the data. Our results also provide an example, where an endpoint divergence in hard spectator-scattering factorizes and is absorbed into colour-octet operator matrix elements. The second part of the thesis is devoted to a series of analyses of non-leptonic B decays in extensions of the Standard Model. The aim of these studies is twofold: on one hand we are interested in testing the sensitivity of these decays to new physics; on the other hand, we look for actual discrepancies between theory predictions and experimental results, trying to explain them in the context of a new physics model. Concerning the first aspect, we consider two well-motivated new physics scenarios, in which large deviations from the Standard Model are expected, ie the MSSM with large tan beta, and a supersymmetric GUT in which the large neutrino mixing angles give rise to a large mixing between the right-handed quarks. We find that, in both cases, effects in non-leptonic B decays are small, when constraints from other flavour observables, like leptonic B decays, are taken into account. Concerning the second issue, we focus on the discrepancies between theory and experiment, which point to new physics in the electroweak penguin sector of the theory. We consider a modified Z^0 penguin scenario, where this possibility is realized, and we fit the couplings of the model from the B->pi K decays. We show that, in this class of models, a sizeable enhancement of the B->phi pi, phi rho decays is expected, even if this is reduced, when constraints from semi-leptonic B decays are considered.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2009

Author dc:creator

• Vernazza, Leonardo

Contributors dc:contributor

• Beneke, Martin

• info:eu-repo/classification/ddc/530
• Teilchenphysik
• Standardmodell
• Hadronischer Zerfall
• CP-Parität
• Physik
• CP-Verletzung
• hadronischer B-Zerfall
• particle physics
• standard model
• hadronic B decay
• CP violation

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113621%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A51318