# Colloquium abstracts

**J. Sengupta**

IACS, Kolkata

August 11, 2022

**The quantitative distribution of Hecke eigenvalues of cusp forms: Sato-Tate, Lang-Trotter and all th**: For holomorphic cusp forms of weight $k$ (even), level $q$ one knows that the Hecke eigenvalues (unnormalised) are all algebraic integers belonging to a fixed number field $K$ say. This immediately implies that the number of primes $p$, $(p , q )= 1$ such the normalised Hecke eigenvalues $lambda ( p ) = a ( p ) / p^{ ( k - 1 ) /2 }$ where $k$ is the weight $= alpha, alpha in [ -2, 2 ] , {alpha}$ algebraic is finite. However the number of the unnormalised $a ( p )$ 's with this property i.e $a ( p ) = eta, eta in O_K$ fixed could a priori be infinite and is the subject matter of the Lang-Trotter conjecture. We will try to pose these questions in the case of non-holomorphic Maass cusp forms.