Thermodynamic Study Of Heavy Quarkions In Holographic Models

Since the QGP generated in relativistic heavy ion collisions is strongly coupled,the perturbation method has failed.However,Ad S/CFT can provide important information for the study of strongly coupled systems.In fact,the unique advantage of holographic principle enables us to study various properties of QGP through gravity.Moreover,holographic method provides important guidance for us in the study of different properties of strong coupling matter.The main structure of this thesis is as follows:Firstly,we briefly introduce the subject background and research significance of this thesis.At the same time,we also briefly introduce string theory and D brane,and review the derivation process of Ad S/CFT and the physical meaning behind it in detail.Besides,we extend the static black hole with planar horizon to the spinning case,which is dual to the rotating QGP.Then we use the Wilson loop to get the free energy of heavy quarkonium.Entropy,binding energy and internal energy are naturally given by the thermodynamic relationship.And the finite chemical potential case with fixed angular velocity also has been studied.It is found that angular velocity may play the same role as chemical potential.It will change the system from confined to deconfined phase with the increase of angular velocity.Thus,the heavy quarkonium will dissolve at a certain separating distance in the deconfined phase.By discussing the free energy,entropy and internal energy of free quarks,we find that these thermodynamic quantities decrease with the increase of temperature.We also study the effect of magnetic field on heavy quark-antiquark pair in both Einstein-Maxwell(EM)and Einstein-Maxwell-Dilaton(EMD)model.The interquark distance,free energy,entropy,binding energy and internal energy of the heavy quarkonium are calculated.It is found that the free energy suppresses and the entropy increases quickly with the increase of the magnetic field B.The binding energy vanishes at smaller distance when increasing the magnetic field,which indicates the quark-antiquark pair dissociates at smaller distance.The internal energy also increases with the increase of magnetic field.These conclusions are consistent in both models.More importantly,we find that in the EM model,quarkonium is easier to dissociate in the transverse direction than in the parallel direction.However,this conclusion is just opposite to that in EMD model.This phenomenon may imply that the dilaton can change the shape of space and interact with the magnetic field.We also study the free energy,entropy and internal energy of a single quark.Finally,we also discuss the holographic Schwinger effect in anisotropic background.First of all,we compute the separating length of the particle-antiparticle pairs at different anisotropic background which is specified by dynamical exponent ? with the isotropic case is ? = 1.Then it is found that the maximum separating length x decreases with the increasing of dynamical exponent ?.This can be regarded as the virtual particles become real ones more easily.Subsequently,we find that the potential barrier is reduced by dynamical exponent ?,warp factor coefficient c and chemical potential ? at small distance.Moreover,we also find the critical electric field is reduced by the chemical potential and dynamical exponent,but enhanced by the warp factor coefficient.