Abstract: Combined observational data suggest that we live in a spatially flat universe that expands in an accelerating rate. The LCDM model is the most economical model explaining the cosmic acceleration in a very good agreement with almost all data. However, other theoretical models, that cannot be ruled out by current data, have been studied in the literature due to the cosmological constant (CC) problems. In my seminar, first I will introduce the audience to the subject, after that I will briefly mention the CC problems, and then I will discuss other alternatives, namely a brane model as well as an interacting quintessence dark energy model. Finally, I will say a few things about the statefinder parameters that can discriminate between different theoretical models with similar expansion history.
