Studying The Temperature Dependence Of Jet Transport Parameter In High-energy Heavy-ion Collisions

A new hot and dense matter-quark-gluon plasma(QGP)have been created in high-energy heavy-ion collisions performed at the Relativistic Heavy Ion Collider(RHIC)at Brookhaven National Laboratory(BNL)and the Large Hadron Collider(LHC)at European Organization for Nuclear Research(CERN).When the hard partons created in the initial stage of high-energy heavy-ion collisions traverse through the produced hot and dense nuclear medium before fragmenting into hadrons,they loss most of energy as a result of multiple scattering with the colored medium.This phenomenon is know as Jet Quenching which is an important hard probe to study the existence and physical properties of quark-gluon plasma(QGP).A key method of studying quark-gluon matter hard probe signal through jet energy loss is extracting and analyzing jet energy loss parameter or the jet transport parameter q which characterizes the mean of the transverse momentum squared per unit path length.Jet transport parameter q directly influence high pr hadron yield,correlation and anisotropy.Present theoretical research suggest jet transport parame-ter q is approximatly proportional to cubic temperature.But some phenomenological study suggest that the simple cubic relation needs correction in order to explain ex-perimental data well,especially for the data of elliptic flow v2.This thesis utilize the perturbative QCD parton model at next-to-leading or-der(NLO)to study high pT single hadron nuclear modification factor RAA and the elliptic flow v2.From the point of view of fitting nuclear modification factor and the elliptic flow experimental data,i.e.,"data driving",we investigate the additional cubic temperature dependence of jet transport parameter q through a great deal of calculation.In practical study,we use higher-twist energy loss frame to incorporate jet energy loss in medium-modified fragmentation functions and utilize the three-dimensional 3+1D ideal hydrodynamics model to simulate the evolution of the hot and dense bulk matter,trying to confirm that besides the jet transport parameter is proportional to cubic temperature,there is an additional Gaussian temperature dependence of jet transport parameter.Our study indicates that if we assume the jet transport parameter is proportional to cubic temperature,the result can not simultaneously describe the nuclear modified factor RAA and elliptic flow v2 well by comparing the calculation with experimental data.When theoretical result can describe the single hadron nuclear modified factor RAA well,the data of elliptic flow v2 calculated in the basics of nuclear modified factor calculation is different from experimental data from middle pT to high However if we assume the jet transport parameter is Gaussian dependence to cubic temperature,the result can describe the nuclear modified factor RAA well,meanwhile,can improve the theoretical result of elliptic flow But the recombination and mechanism of hadron takes a effect to anisotropy at middle pT,which doesn t reflect in this thesis.It may because we can not completely improve the theoretical result of elliptic flow v2.The additional temperature dependence of jet transport parameter is meanly manifested at region of critical temperature,which enhance the anisotropy of high-energy parton jet energy loss and may help us more deeply understand elliptic flow v2 of high pT hadron.