D∗+ reconstruction in proton-proton interactions at √s = 8 TeV with the ALICE detector at the Large Hadron Collider.

Abstract

One of the least understood states of matter in the creation of the universe is the Quark Gluon Plasma (QGP). In order to understand more about this state heavy flavour particles are measured in collisions containing QGP and in collision without QGP. The main observable for studying the energy loss differences between both is the nuclear modification factor (RAA ). In this factor both a cross-section for the QGP situation and a baseline measurement, which is extracted from pp collisions, are included. The reconstruction of the D∗+ in the hadronic channel D∗+ → D0 π → Kππ using the 2012 ALICE proton-proton data at √s = 8 TeV will provide such a baseline as well as improve current perturbative Quantum Chromo Dynamics (pQCD) calculations. Cross-sections extracted from reconstructions can be used to improve the current D-meson cross-section as well as the RAA which currently have high uncertainties. The limiting of these uncertainties is done by measurements at higher collision energies but the uncertainties in a measurement can also be improved via higher transverse momentum references. In this thesis the reconstruction for D∗+ mesons is studied with respect to the EMCal trigger, which give higher transverse momentum references than minimum biased triggers. The focus will be on the quality assurance of the data sample with respect to all D-mesons and on the signal extraction for the D∗+ mesons. As a perspective the full correction of the raw yield and the determination of the production cross-section for D∗+ mesons are shown. The combination of results hints that it would be useful to keep on measuring the cross-section for triggered data, in order to increase the momenta range of the measurements. The quality assurance concludes that a new reconstruction is necessary to correct local problems. The production cross-section should be re-evaluated once the new reconstruction and the Monte-Carlo simulation for this trigger are available.