Prompt charged particle production measurements in small collision systems at the LHCb experiment

Abstract

This thesis includes two measurements of prompt charged particle properties from proton-proton and proton-lead collisions at √sNN = 5.02TeV recorded at the LHCb experiment at CERN. One is the multiplicity distribution and the other is the multiplicity dependence of the average transverse momentum. Charged particles are measured in 0.5 < pT < 8.0 GeV/c and 2.0 < ηLAB < 4.8. The pseudorapidity dependence of both measurements in the forward region has been studied for the first time in this thesis. The thesis is structured as follows. In Chap. 1 is an introduction to the topic where the current knowledge and open problems of the field are summarised. Also, the new information provided by this work to the field will be explained. In the Chap. 2, a more profound theoretical description is made. Starting from the standard model and going through strong interaction theory until arriving at the particle production models, saturation and quark-gluon-plasma. Then, the methodology of the analysis is detailed. Starting from the description of the dataset used in this analysis (Chap. 4) and explaining the preparation and selection (Chap. 5). The core of the analysis is detailed in Chap. 6 where all the analysis techniques are explained. The systematic uncertainty estimation is done in Chap. 7 and results are shown in Chap. 8. Some prospects for future measurements in central ion collisions at LHC-Run5 are done in Chap. 9. Finally, some discussion and conclusions are provided in Chap. 10. A summary in Galician is presented in Chap. A, and the bibliography is included at the end of the document.