Particles and Quantum Field Theory


 

High energy physics and cosmology deals with the cognition and study of nature and the universe at the most fundamental level. The most important questions which arise in this context may be scrutinized at two distinct levels: First, in large scales, for instance how has the universe evolved since big bang up to now? When and how was the universe created basically? How galaxies and nebulas in the universe have formed and is it possible that there are some other universes alongside our universe ? Can one consider the universe as a particle and define a wave function for it? And finally, what is the fate of the universe?
On the other hand, in the smallest dimensions these fundamental questions may be arisen : what are the elementary constituent parts of the world and how do they interact? What are the fundamental interactions in the universe? How can one consider these forces as different aspects of a Great Unified Theory? Do extra dimensions have physical reality? If the answer is affirmative why are they intangible? Why the abundance of particles is considerably preponderant in comparison to antiparticles in the universe? Why do coupling constants of the fundamental forces lie in different scales? And where do these fundamental constants emanate from?
The answers to these questions are categorized in the form of high-energy physics, which includes particle physics, quantum field theory, classical and quantum gravity and cosmology, as well as supersymmetric, supergravity and superstring theories.