The Study On The Photoproduction Of Double Heavy Quarkonium At The LHC

Since the J/? was discovered experimentally in 1974,there has been an important and meaningful research topic in the field of particle physics----heavy quarkonium physics.After more than forty years of research,heavy quarkonium physics still attracts the attention of theoretical and experimental physicists.In experiments,countries are actively constructing colliders,such as the Tevatron particle accelerator of Fermilab Laboratory,the Beijing Electron-Positron Collider(BEPC),and the Large Hadron Collider(LHC)of European Organization for Nuclear Research,which provide experimental platform for the study of heavy quarkonium physics;In theory,in order to explain the mechanism of heavy quarkonium production,particle physicists have proposed many theoretical models,for example the Color-singlet Model(CSM),Color-Evaporation Model(CEM),Nonrelativistic Quantum Chromodynamics(NRQCD)theories,etc.,and achieved excellent results in both theory and experiment.To study the production and decay process of the heavy quarkonium,which are generally factorized into two parts:the perturbation part and non-perturbation part.For the processing of the perturbation part,there is a well-established theory—perturbative quantum chromodynamics(QCD).However,for the treatment of non-perturbation processes,there are relatively few methods.Generally,the universal long-distance matrix elements are extracted from experiments or calculated by lattice QCD.Therefore,the processes of the heavy quarkonium production and decay can be used to study both perturbation QCD and non-perturbation QCD,which is an ideal platform for QCD research.At present,due to the continuous improvement of the energy and luminosity of the collider,many heavy quarkonium channels can be studied by experimentally,such as heavy quarkonium associated with single jets production,heavy quarkonium associated with double jets production,and heavy quarkonium associated with W±/Z/?production,heavy quarkonium associated with single lepton production,heavy quarkonium associated with double lepton production,and double heavy quarkonium production etc processes.Particularly,the study of double quarkonium production channels has attracted the attention of a large number of particle physicists,such as the experiment of double charmonium produced by e+e-collision in Belle Collaboration,the process can be well explained by the relativistic correction and NLO NRQCD correction;The production of double charmonium at the LHC has been studied experimentally,different theoretical models have been used to explain the production process of double quarkonium at the LHC.Although the LHCb measured cross section can be reasonably well described by the NLO result in the single(hard)parton scattering(SPS)mechanism,however,there is no satisfactory explanation for CMS experiments.In order to further understand the production mechanism of heavy quarkonium,we need to study more the production process of heavy quarkonium,in which the production of double quarkonium is an important research object.In this paper,we study the photoproduction of the double quarkonium at the LHC,and the theoretical estimation for the leading order(LO)of double heavy quarkonium is given.In the first chapter,we briefly introduced the QCD theory,presented the theoretical framework of the heavy quarkonium production based on the NRQCD theory,and introduced the heavy quarkonium physics.In the second chapter,we introduced two production processes of the heavy quarkonium H at the LHC:pp?p?p?H+X and pp?pyyp?H+Xprocesses,and the treatment method of the electromagnetic effects is also introduce-the equivalent photon approximation method in these processes.In the third chapter,we investigated the photoproduction of double J/?(T)to LO based on the NRQCD factorization framework at the LHC with three different forward detector acceptances.In this processes,we presented the total cross section of double J/?,and gave the distribution of the transverse momentum and rapidity;Meanwhile,we also studied the photoproduction of the double T at the LHC.From our results,we can see that the double J/? photoproduction has the potential to be detected at the LHC,however photoproduction of the double r is very di:fficult to detect under the current experimental conditions.The main innovation of this paper is that we investigate the photoproduction of the double J/?(r)at the LHC with three different forward detector acceptances for the first time.From our calculation results,the cross section of the double J/? can reach the magnitude of pb at the LHC with forward detector acceptances ?1 and ?3;As for the ?=?2,the cross section of the double J J/? is less than 200 fb.If we consider the integrated luminosity of 200 fb'1 at the LHC,it can be roughly estimated that the number of double J/y? is about 3900,500,and 3600 events for detector acceptances with ?1,?2 and ?3,respectively.Therefore,it is possible to observe the photoproduction of the double J/? in the experiments.A detailed study of the process will help to further understand the production mechanism of the heavy quarkonium.