Chiral Magnetic and Vortical Effects in Relativistic Heavy Ion Collisions
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In the present dissertation, the derivation of the chiral magnetic effect (CME) and chiral separation effect (CSE) from the Hamiltonian of Dirac fermions in a magnetic field is given. It is shown that the CSE is related to the spin polarization vector of massless fermions and becomes less important when fermions are massive. The chiral kinetic equations for massless fermions in a magnetic field are also derived from the Lagrangian of a massless fermion either using the semiclassical approximation or by solving the Dirac equation. The chiral vortical effect (CVE) and chiral vortical separation effect (CVSE) are similarly derived as for the case of the CME and CSE. The interplay between the vector and axial vector charge densities can generate two kinds of gapless collective modes, called the chiral magnetic wave (CMW) and the chiral vortical wave (CVW), and both can be derived in the hydrodynamic and kinetic approaches. Effects of the CMW and CVW in relativistic heavy ion collisions are then studied by solving the chiral kinetic equations numerically using the testparticle method. It is found that, the CMW generated by the magnetic field in a quark matter with its initial conditions modeled by the Bjorken boost-invariant model can lead to different elliptic flows for particles of positive and negative charges if the chirality changing scattering (CCS) between massless quarks and antiquarks is included. Neglecting the Lorentz force acting on quarks and antiquarks as in other studies, it is found that the obtained elliptic flow splitting depends linearly on the charge asymmetry of the quark matter, similar to that measured in experiments at RHIC. The magnitude of the splitting is, however, less than the experimental results even if the magnetic field is taken to have a long lifetime. The presence of a vorticity field in the quark matter is found to only lead to an axial dipole moment in the transverse plane but not an elliptic flow splitting between particles of positive and negative charges. Including effects from both the magnetic field and the vorticity field can, on the other hand, leads to the splitting between the elliptic flows of positivelyand negatively charged particles even for quark matter of zero charge asymmetry. However, the inclusion of the Lorentz force changes the sign of the slope of the charge asymmetry dependence of the elliptic flow splitting, leading to a result opposite to that from the experiments and thus making it unlikely that the observed elliptic flow splitting between charged particles is due to the CMW. Including in quark scattering the correction to the phase-space measure due to the vorticity field, the chiral kinetic equations are also used to study the spin polarization of light quarks in a rotating quark matter with its initial conditions taken from a multiphase transport (AMPT) model. Converting the spin-polarized light quarks to hadrons using the quark coalescence model leads to the spin polarizations of Ʌ and Ʌ ¯ (bar should be over Ʌ) hyperons that are comparable with experimental results both in magnitude and trend as a function of collision energy.
Sun, Yifeng (2017). Chiral Magnetic and Vortical Effects in Relativistic Heavy Ion Collisions. Doctoral dissertation, Texas A & M University. Available electronically from