1. Axion. Since the eighties, I have been working on the so-called strong CP violation problem and its relationship to the axion. I introduced a model with an almost invisible axion. In this model, the CP violation problem in strong interactions is solved, but the axion is very difficult to observe. This model is referred to in the literature as the DFSZ (Dine-Fishler-Srednicki-Zhitnitsky) axion model, and there are several experimental groups searching for such axions.
2. Light Cone wave function. The famous factorization theorem for the exclusive amplitudes has been proven in a series of my papers with V.L.Chernyak. The nonperturbative light cone wave functions have been introduced into the theory in the same series of papers. Nowadays this technique is accepted in the community as the basic tool for an analysis of the high energy exclusive amplitudes. The corresponding light cone wave functions are known in literature as CZ (Chernyak-Zhitnitsky) wave functions.
3. Quantum Anomalies in heavy ion collisions. It has been suggested by Kharzeev and Zhitnitsky (2007) that the CP-odd asymmetries observed at RHIC (and later confirmed by the LHC) can be interpreted in terms of the anomalous currents which must be induced due to the quantum anomaly. This area of research initiated by Kharzeev and Zhitnitsky in 2007 became a hot topic in recent years as a result of many interesting theoretical and experimental advances. In particular, the so-called Chiral Magnetic Effect, Chiral Vortical Effect, Chiral Separation Effect, Charge Separation Effect, to name just a few, were based on the pioneer paper by Kharzeev and Zhitnitsky (2007).
Current Research and Future Directions
The main goal of my research has been, and continues to be, the application of apparently pure theoretical ideas to phenomenological needs in particle physics. One major project on which I have been working involves the application of the well established theory of strong interaction, the so-called Quantum Chromodynamics (QCD), to the interaction of hadrons in the unusual enviroment when temperature, chemical potential, the so-called theta parameter are non-zero.
Such a study is important in the area where particle physics/ nuclear physics/ astrophysics/ cosmology are overlapped. I believe that this field will be the most exciting area in the nearest future. In particular, I am interested in the axion physics, physics of neutron stars, inflation models, the dark matter problem, baryogenesis, etc.
The development of the early Universe is a remarkable laboratory for the study of most nontrivial properties of particle physics. 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, Brookhaven and the LHC, Geneva, where such an unusual environment, as mentioned above, can be achieved.
I also do research at the interface between particle theory and condensed matter theory. Specifically, the conceptual similarity between particle physics and condensed matter systems allows us to use condensed matter as a laboratory for the simulation and investigation of the most intricate properties of the quantum ground state.