Sharif Digital Repository

The theoretical and experimental investigation of quantum chromodynamics phase diagrams is one of the most important subjects in elementary particle physics. Some properties of this diagram are the existence of the hadron phase at low temperatures and chemical potentials, color superconductivity at low temperatures and high chemical potentials, and quark-gluon plasma at high temperatures and chemical potentials. In recent years, the main focus was on the study of quark matter at very high chemical potentials. In particular, the formation of magnetic dual chiral density wave was investigated using the Nambu–Jona-Lasinio effective model. In this thesis, we study, in particular, the phase... 

Wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems (NEMS) and assembly of nanostructures remarks the importance of nanostructures’ motion in electric fields. Despite of many reports on manipulation and assembly of nanowires (NWs) in non-uniform and alternating electric fields by dielectrophoresis, and also rotation of NWs in rotating electric fields, there is still a lack of knowledge on rotational and translational dynamics of metallic and dielectric NWs in uniform static electric fields. In this dissertation, we study the dynamics of silver (Ag) and titanium dioxide (TiO2) NWs, with diameters and lengths in the range of 40 to 100... 

Worldline formalism provides an effective and intuitive method in order to obtain the full prop- agator of a system with definite degrees of freedom and the one-loop effective action of such a system interacting with a background field. The covariance of relations and results facilitates the generalization to more complex geometries and symmetries. Feynman for the first time arrived at a relation for the relativistic orbit of a quantum particle in vacuum. In the same year, Schwinger employed a differential method to address the problem of vacuum polarization. The purpose of the current research is to review both of these methods in their search for a polarized vacuum, Lorentzian and gauge...