The magnetic moment of leptons at high temperatures

The magnetic moment is a measure of the interaction of charged particles with the magnetic field. It depends on the mass of the particles. All charged particles have an intrinsic magnetic moment due to their intrinsic spin, whereas the neutral particles do not exhibit intrinsic magnetic moment. Charged particles can induce a magnetic moment to neutral particles. This induced magnetic moment of neutral particles is a perturbative effective and is produced radiatively at higher orders of perturbation. There is still information not known about the structure and magnetic moment of particles. The magnetic moment of particles is not precisely calculated for cases when the effective mass of particles is modified due to radiative corrections at high energies. Therefore, the magnetic moment of particles needs to be calculated for individual particles that interact differently. This thesis is comprised of an overview of the magnetic moment of all flavors of leptons in vacuum (at T=0) as well as in a medium. Due to the interaction with the medium, the effect of high temperatures of the medium contribute to the magnetic moment. Some of the cosmological applications of temperature dependent magnetic moment are also discussed.