Performance study for the D*+ reconstruction using the ALICE ITS upgrade

Abstract

According to calculation of quantum chromodynamics on the lattice, a phase transition to a quark-gluon plasma occurs under the conditions of high energy density and temperature. These conditions are reached in the ALICE experiment with high-energy collisions of lead nuclei. The ALICE detectors, including the Inner Tracking System, will be upgraded in 2019 - 2020. This research project studied D*+ reconstruction with the upgraded ITS. To study the performance, the improvement of detecting D*+ mesons with low pt and the expected significance of D*+ mesons for p-p collisions as well as for Pb-Pb collisions is investigated. For both subjects a Monte-Carlo simulation program PYTHIA is used to generate high-energy collision events. To study the acceptance of D* + mesons with a low pt, a minimum pt of 40 MeV/c is used for the soft pion. To calculate the significance, real data is used for estimating the background. The data to calculate the background is produced in p-p collision at sqrt(sNN) = 13 TeV and Pb-Pb collisions at sqrt(sNN) = 2,76 TeV. 58 percent of the D*+ mesons with a pt between the 0 and 0.5 GeV/c can be reconstructed, and 90 percent or more for D*+ mesons with a pt higher than 0.5 GeV/c. The significance is calculated higher than 5 in all pt ranges up to 36 GeV/c, except for D*+ mesons with a pt lower than 0.5 GeV/c produced in Pb-Pb collisions.