Studies Of Chiral Electromagnetic Field And Correlative Effects In Relativistic Heavy Ion Collisions

When two relativistic heavy ions collide with a nonzero impact parameter, an electromagnetic field of enormous magnitude is produced in the direction of angular momentum of the collision. An electromagnetic current will be introduced in the direction of the magnetic field when a nonzero chirality is present in such a situation. This is the chiral magnetic effect.The chiral magnetic effect predicts the preferential emission of charged particles along the direction of angular momentum in the situation of off-central relativistic heavy-ion collisions due to the presence of nonzero chirality. Both the de-confinement and the chiral phase transitions are essential requirements for the chiral magnetic effect to take place. In a relativistic heavy-ion collision this current leads to an excess of positive charge on one side of the reaction plane and negative charge on the other.We used the Wood-Saxon nucleon distribution to calculate the electromagnetic field for off-central nucleus-nucleus collision. We show that an enormous electromagnetic field can indeed be created in off-central relativistic heavy-ion collisions during the RHIC and LHC energy regions. The electromagnetic field distributions of eBy (eBx) and eEy (eEx) are highly inhomogeneous. The enormous electromagnetic field is found to be created just after the collision, and the magnitude of electromagnetic field of LHC energy region is larger than that of RHIC energy region at small proper time(τ< 8.0 × 10-3 fm/c). One finds that the electromagnetic field in the LHC energy region decreases more quickly with the increase of the proper time than that of RHIC energy region. As the proper time T increases to a certain value τ～8.0×10-3 fm/c, the magnitude of electromagnetic field in the RHIC energy region begins to be greater than that of LHC energy region.The dependencies of the ratio of eBy/(eB) on x and y at different collision energies at RHIC and LHC and at different proper time are studied. In most cases, the ratio eBy/(eB) approaches 1, so using eBy to replace (eB) is a good approximation. But one should note that the ratio eBy/(eB) is between 0.5-1.0 along the x= 0 line.We have systematically studied the spatial distribution features of background electromagnetic field in relativistic heavy-ion collisions at the energies reached at LHC and RHIC. The features of spatial distributions of electromagnetic fields at (?)= 900,2760 and 7000 GeV in the LHC energy region and (?)= 62.4,130 and 200 GeV in the RHIC energy region have been systematically studied. Compared with the magnetic field spatial distributions, the electric field spatial distributions are not smooth, which have some distribution peaks on the surface of spatial distributions. It is found that when CMS energy (?) increases, the electric field spatial distributions become more and more smooth, and the peaks almost disappear.We also study the dependences of the electromagnetic field produced by the thermal quark in the central region with different impact parameters on the proper time r in the RHIC and LHC energy regions. One can find that when r and impact parameter b become smaller and smaller, the electromagnetic field becomes more and more strong. The maximum of the electric field eE at (?) = 900 GeV can reach 2.0* 105 MeV2. This value is much larger than that of (?)= 62.4 GeV in the RHIC energy region. As for the periphery collisions, the contribution of produced particles to the electromagnetic field becomes very small.A system with a nonzero chirality responds to a magnetic field by inducing a current along the magnetic field. This is called the chiral magnetic effect. The chiral magnetic effect can be studied using heavy ion collisions. The possible experimental observation of the chiral magnetic effect would be direct evidence for the existence of gluon configurations with nontrivial topology. Furthermore it will signal P-and CP-violation in QCD on an event-by-event basis. A thorough theoretical understanding of the chiral magnetic effect will help the experimental analysis by offering the possibility of more accurate predictions of the observables.Some basic concepts and definitions of the chiral magnetic effect are introduced in the first chapter, such as:instantons,θ vacuum, axial anomaly and QCD in an external magnetic field. The space-time evolution, the distribution of the electromagnetic field and the characteristics of the charge separation effect in the relativistic heavy ion collisions are studied, respectively, in chapter Ⅱ. The third chapter mainly introduces the magnetic field calculation method by using Wood-Saxon nuclear distribution. The spatial distribution of background magnetic field in RHIC and LHC energy regions are shown. The magnetic field distributions from the produced thermal quarks in RHIC and LHC energy regions are also calculated in Chapter Ⅲ. The main contents of the chapter IV are the calculation of the electric field by using the Wood-Saxon nucleon distribution, and the discussion of contribution of the thermal quark to the electric field. The chiral magnetic effects including chemical potential, the chiral electric current, the chiral electric charge current and the chiral magnetic conductivity are studied in chapter V. The sixth chapter mainly analyzes the experimental results of ALICE and STAR. The seventh chapter is the summary and outlook of this research.In summary, the discussions obtained in this study are helpful to study chiral magnetic effect and chiral magnetic wave in the RHIC and LHC energy regions.