Boosting the discovery potential of LHCb by developing a new search for diphoton resonances and an alternative muon reconstruction technique using GPUs

Abstract

The main part of this thesis is devoted to describe a search for a diphoton resonance in the $[5,20]~$ GeV mass region with $pp$ collision data taken with the LHCb experiment during 2018 at an energy $\sqrt{s}= 13~$TeV. This work describes the first physics analysis using only photons detected by the calorimeter at LHCb. A precise calibration of the different selection steps is performed, particularly for the trigger selections. World best sensitivity for an ALP produced via gluon fusion and decaying to two photons is expected in the $[5,10]~$GeV region. The result is also interpreted as a $B_s^0$, $B^0$ or $\eta_b$ meson decaying to two photons and expected upper limits on the branching fractions are reported. The thesis is also devoted to the development of a tracking sequence using the VELO and MUON stations of the LHCb detector with a momentum resolution of $\sim5\%$ for the GPU implementation of the trigge