Centrality Dependence Of Prompt ?_c⁺ Production In P-Pb Collisions At S_NN^1/2=5.02 TeV With ALICE

Quantum chromodynamics?QCD?predicts that quarks and gluons bound to nu-cleons will be released from confinement and hadrons will be transformed into a new material phase,namely Quark Gluon Plasma?QGP?,at high temperature and high energy density.This material phase exists in the early evolution of the universe and in the dense stars such as neutron stars.Therefore,quark gluon plasma is of great significance for exploring the properties of the material structure in the early universe.It has been proposed that the extreme condition for the formation of Quark-Gluon Plasma can be achieved by high-energy heavy-ion collisions.The Large Heavy Ion Collider Experiment?ALICE?on LHC is devoted to the study of heavy ion colli-sion physics.One can observes the collective flow effect,the strangeness enhancement,jet quenching and other signature to study QGP.Heavy quarks?charm quarks and bottom quarks?due to their large masses pro-duced in the early stage of hard scattering and thus experience the whole evolution of the medium created in heavy-ion collisions,interact with hot and dense matter,and carry information about the medium.Therefore,heavy quarks are excellent probes in high-energy heavy ion collisions.By measuring the yield of heavy-flavor hadrons?mesons and baryons?in the final state,we can infer the properties of the medium.Various heavy hadrons were measured?such as D mesons,?_c,?_c in the LHC-ALICE central rapidity region and heavy quarkonium such as J/? were also studied in the forward rapidity region.In order to compare in different collision systems and have a deep understanding of QGP,the heavy hadrons have been studied in pp,p-Pb and Pb-Pb collisions at dif-ferent energies at LHC-ALICE.Thermal effect is involved in heavy ion collisions,and cold nuclear Matter effect is also considered in nucleon-nucleus collisions.The colli-sion environment in small systems can be as a reference for the thermal environment of QGP.Nuclear Modification factor R_AA(R_pA in the case of nucleon-nucleus collisions)reflects the quantitative relationship between heavy hadron yields in nucleus-nucleus collisions and nucleon-nucleon collisions,which can be used to analyse energy loss in hot and dense medium relative to QCD vacuum.Besides,one can explore how the hot e.nvironment of heavy ion collisions affects particle production mechanism by measuring the ratio of ?_c⁺/D⁰.This analysis is aimed to get the spectra of ?_c⁺ in different centralities via the reconstruction by ?_c⁺?pK_S⁰ decay channel.In this thesis,QGP and heavy ion colli-sion are briefly indroduced firstly,as well as the importance and research progress of heavy-flavor hadrons.Then,the ALICE experimental setup and four sub-detectors involved in this analysis are described.The experimental analysis scheme will be elaborated from the aspects of event selection,candidate particle selection,signal extraction,reconstruction efficiency,acceptance,feed-down correction and so on.Fi-nally,the experimental results are obtained.In this analysis,topological properties of K_S⁰ and ?_c⁺ are considered and the signal is extracted by fitting the invariant mass spectrum,and then the transverse momentum spectrum at different centrality is obtained after correction.The results show the centrality dependence of ?_c⁺ production,there are more production in central collisions.In addition,the ?_c⁺/D⁰ ratios in different centrality are given.The ratio has an enhancement in intermediate transverse momentum region.