Towards a Dark Sector Model from String Theory

I will describe a proposal for a unified dark sector model in string theory with the following features: The model-independent axion descending from the Kalb-Ramond 2-form field is identified with the dark-matter field, and the real part of a Kahler modulus field associated to the radius of one of the extra spatial dimension accounts for dark energy. The expectation value of the dilaton field is stabilized by a gaugino condensation mechanism. A dark-energy potential corresponding to a realistic low-energy scale results from some gentle tuning of the stabilized expectation value of the dilaton.