Grant: Subatomic Physics Envelope - Individual

There are fundamental links between cosmology and particle physics, which have been well established at all scales. In particular, the physics of the early Universe, baryogenesis, cosmological nucleosynthesis, etc. is based on our modern understanding of particle physics. This realization has made the early Universe a marvellous laboratory for studying fundamental physics, in particular the vacuum structure of the theory. Conversely, knowledge of the behaviour of fundamental physics at high temperature gives information about what happened shortly after the Big Bang. What is more remarkable is the fact that these phenomena at the QCD scale can be, in principle, experimentally tested in heavy ion collisions at RHIC (relativistic heavy ion collider), Brookhaven National Laboratory, and at the LHC (Geneva, Switzerland) where such unusual environment can be achieved. The goal of the project is the study of QCD as part of the standard model in the unusual environment when temperature T, chemical potential and the so-called theta- parameter are non-zero. This knowledge gives a reliable information about what have happened about 14 billion years ago soon after the Big Bang at the temperature T=170 MeV. The understanding of the corresponding phase diagram (as a function of these external parameters) is one of the most challenging problems in QCD. It is generally accepted that the theta parameter was not vanishing during the QCD phase transition. First part of my project is devoted to study all these hard questions using a simplified version of QCD, which however preserves all the relevant elements of strongly coupled QCD such as confinement, degeneracy of topological sectors, nontrivial theta dependence, and many other important aspects which allow us to test some fascinating features of strongly interacting QCD, including some aspects of the long range order. The corresponding studies also reveal a deep relation between strongly coupled QCD and some topologically ordered condensed matter systems. The second part of my project is application of these fundamentally new ideas to heavy ion collisions, astrophysics and cosmology. In particular, the violation of local CP invariance in QCD has been a subject of intense studies for the last couple of years as a result of very interesting ongoing experiments at RHIC and the LHC. The main idea to explain the observed asymmetries is to assume that the effective CP violating theta parameter is induced on a large scale as a result of collision. This leads to large CP odd domains. Why are these CP odd domains large? We argue that the long range order in QCD is responsible for such an unusual behaviour. Due to the differences in interactions between quarks and antiquarks in the presence of the theta parameter the local separation of charges may take place. This phenomenon can be tested at RHIC and the LHC. Preliminary results at RHIC and the LHC support the ideas on the nature of the charge separation effect. Finally, we apply the same ideas to cosmology. The unique features of these topological fields have inspired a proposal that the observed dark energy in the universe may in fact be related to such pure topological, non- propagating, long-ranged fields. It is quite remarkable that this fundamentally new type of energy can be, in principle, studied in a laboratory by measuring the so-called topological Casimir Effect.