The Production Of The Hadrons Tagged By The Photons In PP Collision

In the 1970s,Tsung-Dao Lee and other famous scientists predicted that,in extreme relativistic heavy ion collisions,a large amount of energy in a short period of time within the limited space of gathering,are likely to form a new material of high temperature and density of the form.This kind of material is composed of quarks and gluons,and they are no longer confined to the hadronic phase,called quark-gluon plasma(QGP).This prediction promotes the development of the relevant scientific research.Numerous studies have shown that in the early stages of the big bang,the quark-gluon plasma may be produced.Therefore,finding the QGP produced signal and studying its nature has a great significance for understanding the formation and evolution of the universe.In recent decades,many research institutions all over the world established many particle collidrs,the representative of which are the BNL Relativistic Heavy Ion Collider(RHIC)and the CERN Large Hardron Collider(LHC),studying the emergence of the extreme relativistic heavy ion collisions quark-gluon plasma.After a long time of study,the scientists proposed some observations that can determine QGP produced.For example:the increase of strange particles,the lower yield of J/? the collective flow effect,jet quenching effect,the production of large horizontal momentum photons and so on.Among them,the photons are not charged,and do not interact with other particles strongy,so they can easily be detected.The photons carry the relevant information in the early stage of collision,and there are great advantages that photons as the probe signal.Usually people think that high energy nucleus-nucleus collisions produce QGP,but high energy nuclear-nuclear collisions do not produce QGP.Therefore,particle characteristics in the high ener-gy nucleon-nucleon collision can be used as reference to distinguish the particles characteristics of the high energy nucleus nucleus collisions,so as to understand and judge the QGP produced and properties in nuclear nuclear collisions.This thesis is based on the perturbation QCD theory to study the production of hadron taged by the large horizontal momentum photons in high-energy nucleon-nucleon collision.In first time we check the photon spectrum in the leading order perturbation QCD parton model.In the nuclear-nuclear collisions,hard scattering process photons can be divided into direct photons,which are produced by compton process or annihilation process,and fragmentation photons,which come from the fragmentation of final state partons.And then studied the production of the large horizontal momentum hadron tagged by photon in the nucleon-nucleon collision of RHIC/LHC enery zone.On the one hand,our results show that in different collision energy and differ-ent photon-hadron horizontal momentum,theryoretical data is in keeping with the experimental values,and prove that Perturbation QCD strong prediction ability.On the other hand,the theoretical calculation shows that,in the Dpp spectrum of large horizontal momentum hadron tagged by photon,the results of the NLO can describe zT>1 experimental data,but LO can give zT<1.In fact,in LO cases the photon horizontal momentumused equal to the corrective jet initial horizontal momentum,so the hadron horizontal momentum coming from the corrective jet fragmentation less than he photon horizontal momentumused,so it describe zT<1.About the large horizontal momentum hadron accurate description of Perturbation QCD,especially near the zT = 1 or zT>1 zone,the higher order NLO calculated need to be consid-ered at least.Our study has promoting significance for the calibration of the QGP hard probe signal.