$CP$ violation studies in three-body charmless $B^\pm$ decays and contributions to the LHCb SciFi Tracker

In the first part of the thesis, we present studies on three-body charmless $B^\pm$ decays. The analysis is performed using LHCb dataset from proton-proton collisions at the centre-of-mass energy of 7 TeV and 8 TeV collected in 2011 and 2012, respectively, corresponding to an integrated luminosity of 3.1 fb$^{-1}$. We measured the inclusive $CP$ asymmetry of the four channels: $B^\pm\to K^\pm\pi^+\pi^-$, $B^\pm \to K^\pm K^+ K^-$, $B^\pm \to \pi^\pm\pi^+\pi^-$ and $B^\pm\to \pi^\pm K^+ K^-$. $CP$ asymmetries were also studied along the phase space. The second part of this thesis is devoted to my contribution to the LHCb SciFi Tracker, a detector made of scintillating fibres. It presents the experimental setups used to characterise the scintillating fibres which need to meet specific requirements to be able to operate under the running conditions foreseen for the LHCb upgrade. In addition, we discuss the results on the development of fibres made of a new class of scintillating material denominated as Nanostructured Organosilicon Luminophores (NOL). They were found to have a decay time constant at least two times shorter than the fastest scintillating fibres.