Screening Dark Energy

Justin Khoury

November 15, 2010

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Abstract: This talk explores the possibility that the dark sector includes new degrees of freedom (generally scalar fields) that mediate additional long range forces, thereby directly impacting the growth of structure. The theories of interest therefore predict deviations from General Relativity on the largest scales. To ensure consistency with constraints from tests of gravity, these theories exploit a screening mechanism that hides these scalars locally. We discuss existing screening theories and their implications for cosmology.