First measurements of radiative B decays in LHCb
- Autores: Albert Puig Navarro
- Directores de la Tesis: Ricardo Graciani Díaz (dir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2012
- Idioma: inglés
- Tribunal Calificador de la Tesis: Francisco del Aguila Giménez (presid.), Lluís Garrido Beltrán (secret.), Pierluigi Campana (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX Dipòsit Digital de la UB
- Resumen
Radiative decays of B mesons, a good example of Flavor Changing Neutral Currents, are interesting for the study of physics beyond the Standard Model, as new high-energy phenomena can enter in the loop. The LHCb experiment, designed to study b- and c-hadron physics at the LHC, is an ideal candidate for the study of this type of decays. However, in order to effectively study radiative B decays, good trigger performance is needed. Two trigger strategies have been studied, one exclusive and one inclusive: on one side, the already existing exclusive lines have been modified, and, on the other side, a new set of inclusive topological lines, specific for radiative B decays, has been introduced. Their performance in 2011 has been assessed both on simulation and on data, and the strategy for 2012 has been outlined. In addition, the full 2011 dataset collected by LHCb has been used to extract the ratio of branching fractions BR(B ? K??)/BR(Bs ? ??), which has been measured to be 1.31 ± 0.08(stat) ± 0.04(syst) ± 0.10(fs/fd). From this result, and using the well-known value for B ? K??, the branching fraction of Bs ? ?? has been found to be (3.3 ± 0.3 )x10?5, largely improving previous results. This work puts the basis for future developments within the radiative decays group in LHCb, as it settles the trigger strategy on one hand and provides a detailed study of the backgrounds involved in the two studied decays, on the other. This will be very useful for future analyses, such as the CP asymmetry measurements in B ? K?? or the photon polarization in Bs ? ??.
