Cristian Dumitru Popescu is a Romanian-American mathematician at the University of California, San Diego. His research interests are in Algebraic Number Theory, and in particular, in special values of L-functions. He formulated and proved function-field versions of the Gras conjectures and Rubin's integral refinement of the abelian Stark conjectures. He has also made important contributions to the Stark conjectures over number fields, formulating an alternative to Rubin's refinement, known as Popescu's conjecture. Although slightly weaker than Rubin's conjecture, it has the advantage that it can presently be shown to remain true under raising the base field or lowering the top field of the extension. Recently, Popescu and Cornelius Greither have formulated equivariant versions of Iwasawa's main conjecture over function fields and global fields, proving most the version for function fields. These conjectures have important implications for the Brumer–Stark conjecture and Gross' conjecture on special values of L-functions.