Phase diagram of bosonic matter with additional derivative interaction

Abstract

Equation of state of uncharged bosonic matter is studied within a field-theoretical approach in the mean-field approximation. Interaction of bosons is described by a scalar field $σ$ with a Skyrme-like potential which contains both attractive and repulsive terms. Additionally we introduce the derivative interaction by including factor $(1+λσ)^{-1}$ in the kinetic part of Lagrangian where $λ> 0$ is the model parameter. Numerical calculations are made for strongly interacting matter composed of $α$ particles. It is shown that ground-state binding energy and equilibrium density of such matter drop with increasing $λ$. The liquid-gas phase transition and the Bose-Einstein condensation are studied by using different thermodynamic variables. We calculate also spinodal lines which give boundaries of metastable states. It is demonstrated that critical temperature decreases with $λ$. Both LGPT and bound condensate states disappear above certain maximum value of $λ$.