Stable equilibrium point and oscillatory motion of the Universe in a model with variable vacuum energy

We discuss the mechanism by which the field vacuum energy varies as a result of strong self-interaction. We propose a nonperturbative approach to treat strong interactions and discuss the problem in terms of quasiparticles describing the motion of field modes. The resulting vacuum energy is variable and depends on the state of the system. If the interacting scalar field is related to the cosmological field, an acceleration equation with a stable equilibrium point follows in a simple model, predicting the oscillatory behavior of the scale factor and other cosmological effects.

Figure 1

Schematic representation of the double-well potential $U_{\mathrm{DWP}}(x_i)$.

Figure 2

Inverse of viscosity versus $\frac{1}{{\rho }^{\frac{1}{3}}}$ for liquid Ar along the adiabat at constant entropy $S=80\mathrm{J}/(\mathrm{mol}·\mathrm{K})$). The data are from [20]. The line shows the quadratic fit ($R^2=0.99996$).