Publikationsserver der RWTH Aachen University
Exklusive radiative und elektroschwache b -> s und b -> d Zerfälle in nächstführender Ordnung
Abstract
dc:descriptionIn this dissertation the exclusive decay channels B --> V gamma and B --> V l+ l- (V=K*, rho, omega) are discussed. The problem in the treatment of exclusive decays stems from the fact that decay matrix elements contain non-perturbative contributions and therefore cannot be treated entirely in perturbation theory. In the discussed processes three different mass scales are present which open the possibility for expansions which lead to the weak effective Hamiltonian and QCD-factorisation. In this way short- and long-distance physics can be disentangled and be treated perturbatively or parametrised in universal form factors/light-cone-distribution-amplitudes, respectively. One major part of this work is devoted to the calculation of two-loop matrix elements. After the projection of the matrix elements onto the possible Dirac structures hundreds of scalar integrals have to be solved. With the help of the differential equation method and Lorentz invariance identities relations between these integrals can be set up and all scalar integrals can be expressed through only twelve master integrals. These can be solved by the differential equation method. In the last part of this dissertation a phenomenological analysis of the different decay modes is given. The decay channel B --> rho gamma is very well suited to constrain the location of the apex of the unitary triangle. Analysing the Ratio B --> rho gamma to B --> K* gamma, a limit on |V_ts/V_td| can be fixed which is more stringent than the one from the standard fit. Moreover Isospin- and CP-violation will be analysed. These observables have not been measured yet but it is shown that they lead to two more independent constraints on the unitary triangle. Concerning the decays B --> K* l+ l-, a comparison of the theoretical predictions with the recently presented results of the integrated rates shows a deviation by about a factor of two. But as the experimental predictions are covered with big errors, the mismatch is not significant and one has to wait for improved measurements. Unlike the just mentioned decay, the results for B --> rho l+ l- will only be available from the era starting with the LHC. At that time the CKM-elements will be known very accurately. This decay mode can than be used to gain information on the value (modulus and phase) of the Wilson-coefficient C_9 for the b --> d transition.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2005
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Seidel, Dirk
- Contributors dc:contributor
-
- Beneke, Martin
Subjects
dc:subject × 7Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:60029