B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses

Abstract: The Standard Model (SM) of particle physics is the theory that describes the fundamental particles and their interactions, excluding gravity. Despite its success and precision in predicting phenomena, it is known that it is not a complete theory. It does not account for dark matter or dark energy, the asymmetry between matter and antimatter in the Universe, nor the origin of neutrino mass. Consequently, it is of vital importance to investigate possible extensions of this model and measure processes that may reveal new physics. An experiment that contributes to this effort is LHCb, one of the four major detectors located at the LHC particle accelerator operated by CERN. Its research focuses on high-precision measurements of particles involving heavy b and c quarks.

Rare radiative decays of B mesons provide an ideal platform to test the SM and study its possible extensions. These decays cannot occur via tree-level diagrams within the SM description; instead, they proceed through loops in which unknown particles could participate, thereby altering observable quantities.

This thesis presents three interconnected topics within the study of rare radiative decays of B mesons: the calorimeter monitoring tools of the experiment, inclusive radiative selections in the trigger system, and the measurement of the isospin asymmetry of the decay B→K*γ.

Tribunal:

President: Dr. Jean-François Pierre Lucien Marchand

Secretary: Dr. Ricardo Vázquez Gómez

Vocal: Dr. Míriam Calvo Gómez

Suplents:

Dr. Lluís Garrido Beltran

Dra. Maria Aránzazu De Oyanguren Campos

Directors: Dr. Eugeni Graugés Pous and Dr. Carla Marín Benito

Tutor: Dr. Joan Soto Riera