On unification of gravitation and electromagnetism in the framework of a general-relativistic approach

We consider the unification problem for the gravitational and electromagnetic interactions and its possible solution on the basis of the existence of an effective Riemannian space in nonlinear electrodynamicsComment: 3 pages, Talk given at the International Conference RUSGRAV-13, June 23-28, 2008, PFUR, Mosco

A local gauge invariant infrared regularization of the Yang-Mills theory

A local gauge invariant infrared regularization for the Yang-Mills theory is constructed on the basis of a higher derivative formulation of the model.Comment: 7 page

Multiphonon anharmonic decay of a quantum mode

A nonperturbative theory of multiphonon anharmonic transitions between energy levels of a local mode is presented. It is shown that the rate of transitions rearranges near the critical level number $n_{cr}$: at smaller $n$ the process slows down, while at larger $n$ it accelerates in time, causing a jump-like loss of energy followed by the generation of phonon bursts. Depending on parameters, phonons are emitted in pairs, triplets etc.Comment: submitted to Europhys.Let

Thin topological insulator film in a perpendicular magnetic field

We report on a study of an ultrathin topological insulator film with hybridization between the top and bottom surfaces, placed in a quantizing perpendicular magnetic field. We calculate the full Landau level spectrum of the film as a function of the applied magnetic field and the magnitude of the hybridization matrix element, taking into account both the orbital and the Zeeman spin splitting effects of the field. For an undoped film, we find a quantum phase transition between a state with a zero Hall conductivity and a state with a quantized Hall conductivity equal to $e^2/h$, as a function of the magnitude of the applied field. The transition is driven by the competition between the Zeeman and the hybridization energies.Comment: 4+ pages, 1 figure, published versio