Measurements Of Inclusive And Semi-inclusive Charged Jets In Proton-proton Collisions At 13 TeV With ALICE

Exploring the microstructure of matter has always been an important subject for human beings to understand the basic laws of the material world.We know that atoms are composed of nucleus and electrons outside the nucleus,while nucleus is composed of protons and neutrons,and protons and neutrons are composed of quarks,which interact with each other via gluons.Quarks and gluons are considered to be elementary particles.The interaction between quarks and gluons can be described by quantum chromodynamics (QCD),that is,quarks and gluons are confined to hadron nuclei,and free quarks and gluons cannot be extracted from hadrons.Lattice quantum chromodynamics (LQCD) predicts that when the energy density of nucleax matter is higher than the critical point of phase transition,the quarks and gluons bound in the hadron will be in a state of depolarization,forming a free quark gluon plasma (QGP).Quark gluon plasma (QGP) is believed to exist in the early universe after the big bang.The early universe expanded and cooled rapidly.When the temperature decreased to the critical temperature of phase transition,it would evolve into galaxies and retreat into stable nuclear matter,that is,the present universe.Studying the formation process of QGP and its properties will help us to further understand the origin of the universe and the formation of matter.Therefore,the study of QGP generation and properties has become an important topic in high energy nuclear physics.In order to understand the phase transition process of QGP in the early stage of the big bang more clearly,large-scale experimental devices such as the Relativis-tic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) are used to simulate the big bang.The particle beam is accelerated and collided by a large-scale experimental device,and the QGP phase transition condition is achieved in the laboratory conditions,and then-the QGP hot dense substance is generated and its properties are studied.A large ion collider experiment (Alice) is one of the main experiments running on LHC.Its main purpose is to study the generation and prop-erties of QGP by heavy ion collision.The existence time of QGP substance after collision is very short,so QGP substance can not be detected generally,so we can only study the formation and properties of QGP substance by observing the change of probe through the final stable product after collision.In recent years,with the development of high-energy nuclear physics,it is found that in the small system of high multiplicity proton proton collisions and proton lead collisions,some similar characteristics of QGP formation in heavy ion collisions will be produced.So whether there is QGP in the small system is an open question,which needs farther study.So this analysis is based on finding out whether there is QGP like signal in such a small system as proton proton collision.This analysis is based on the 13tev data of highest collision energy and the largest statistics obtained by Alice detector to carry out the research of inclusive and semi-inclusive jets in proton proton collisions.We have studied the yield of inclusive jets and the scattering cross section of inclusive jet to check the calculation process of pQCD.Because this process will involve the normalization of the scattering cross section,additional errors may be introduced.In order to reduce the error as much as possible,we choose to use the charged particle trigger track to measure the recoil semi-inclusive jet yields to carry out the research,since the conditional yield is relatively background free.We select two hadrons with different transverse momentum as the trigger particles,and analyze the recoil jet yields generated by the trigger particles.By using the subtraction of results of two trigger intervals to deduct the relevant background,the relative pure semi-inclusive recoil jet production without background interference is obtained,that is,the transverse momentum distribution of the relative production △recoil.Using the Monte Carlo simulation output,the detector e:ffect on the transverse momentum of the semi-inclusive recoil jets △recoil is then corrected.Then,the corrected recoil jet is compared with the Monte Carlo simulation data to verify the effectiveness of theoretical models.At the same time,the yields of different resolution parameters are also compared,which reflects the collimation behavior of jet fragmentation process.After the analysis of △reciol in different transverse momentum printervals,we also studied the distribution of the azimuth angles correlation Φ(△φ) between the trigger hadrons and recoil jets,and compared with the Monte Carlo simulation data.The background-subtracted correlations on the opposite azimuth side of trigger particles show that their width decrease when the pT recoil jets increase.Further study indicates a widening effect of such correlation Φ(△φ) in high multiplicity events comparing with those unbiased events.Similar effect already appears when comparing central and peripheral AA collisions,where collective dynamics properties emerge in case of high multiplicity events independent of collision systems.Therefore,we expect to study in the future the dependence of such widening effect on multiplicity and trigger pT,so as to provide a basis for further verification of the existence of strong interaction quark matter produced in high multiplicity small system.