Effective growth of matter density fluctuations in the running LCDM and LXCDM models

Understand

We investigate the matter density fluctuations \delta\rho/\rho for two dark energy (DE) models in the literature in which the cosmological term \Lambda is a running parameter.

• In the first model, the running LCDM model, matter and DE exchange energy, whereas in the second model, the LXCDM model, the total DE and matter components are conserved separately.
• The LXCDM model was proposed as an interesting solution to the cosmic coincidence problem.
• It includes an extra dynamical component, the "cosmon" X, which interacts with the running \Lambda, but not with matter.