He works on special values of L-functions and -adic representations of -adic groups at the meeting point of Fontaine's and Langlands' programs. His contributions include:
A conjecture: the Colmez conjecture relating Artin L-functions at and periods of abelian varieties with complex multiplication, a far-reaching generalization of the Chowla-Selberg formula.[2]
A proof of Perrin-Riou's conjectural explicit reciprocity law related to the functional equation of -adic L-functions.[3]
Several contributions to Fontaine's program of classification of -adic representations of the absolute Galois group of a finite extension of , including proofs of conjectures of Fontaine such as "weakly admissible implies admissible"[4] and the "-adic monodromy conjecture" which describe representations coming from geometry, or the overconvergence of all representations,[5][6] and the addition of new concepts such as "trianguline representations"[7] or "Banach-Colmez spaces".[8][9]
A construction of the -adic local Langlands correspondence for , via the construction of a functor (known as "Colmez's functor" or "Colmez's Montreal functor"[10]) from representation of to representations of the absolute Galois group of .[11]
Comparison theorems for -adic algebraic and analytic varieties with applications to a geometrization of the -adic local Langlands correspondence.[12][13][14]
^Cohomologie -adique de la tour de Drinfeld, le cas de la dimension 1, Journal of the AMS 33 (2020), 311–362 (with Wiesława Nizioł and Gabriel Dospinescu).
^Cohomology of -adic Stein spaces, Inventiones mathematicae 219 (2020), 873–985 (with Wiesława Nizioł and Gabriel Dospinescu).