Holographic dark energy with cosmological constant

Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ?HDE model. By studying the ?HDE model theoretically, we find that the parameters d and ?hde are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ?HDE model by using the recent observational data. We find the model yields ?2min=426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ?CDM model (431.35). At 68.3% CL, we obtain ?0.07dark energy and cosmological constant components in the ?HDE model.