arXiv subjects

I. Tkachev

Publications and source records attributed to I. Tkachev.

38 records · Page 3Linked to original sources

arXiv1998

First-order nonthermal phase transition after preheating

During preheating after inflation, parametric resonance rapidly generates very large fluctuations of scalar fields. In models where the inflaton field $ϕ$ oscillates in a double-well potential and interacts with another scalar field $X$, fluctuations of X can keep the ϕto -ϕsymmetry temporarily restored. If the coupling of ϕto X is much stronger than the inflaton self-coupling, the subsequent symmetry breaking is a first-order phase transition. We demonstrate the existence of this nonthermal phase transition with lattice simulations of the full nonlinear dynamics of the interacting fields. In particular, we observe nucleation of an expanding bubble.

hep-ph↗

arXiv1994

Kinetics of Bose-Condensation

The process of condensation in the system of scalar Bosons with weak $λϕ^4$ interaction is considered. Boltzmann kinetic equation is solved numerically. Bose condensation proceeds in two stages: At the first stage condensate is still absent but there is non-zero inflow of particles towards $\vec{\bf p} = 0$ and the distribution function at $\vec{\bf p} = 0$ grows from finite values to infinity. At the second stage there are two components, condensate and particles, reaching their equilibrium values. We show that the evolution in both stages proceeds in a self - similar way and find the time needed for condensation, which is finite.

hep-ph↗