Théorème de Chebotarev et complexité de Littlewood

Resume. The effective version of Chebotarev’s density theorem under the Generalized Riemann Hypothesis and the Artin conjecture (cf. Iwaniec and Kowalski’s Analytic Number Theory, §5.13) involves a numerical invariant of a subset D of a finite group G that we call the Littlewood Complexity of D. We study this invariant in detail. Using this study, and an application of the large sieve, we give improved versions of two standard problems related to Chebotarev : the bound on the first prime in a Frobenian set, and the asymptotics of the set of primes with given Frobenius in an infinite family of Galois extensions. We then give concrete applications to the problem of the factorization of an integral polynomial modulo primes, to the Lang-Trotter conjecture for abelian surfaces, and to the conjecture of Koblitz, with in all three cases better bounds that previously known.