Slopes of the U_7 Operator Acting on a Space of Overconvergent Modular Forms

Abstract

Let \chi\ be the primitive Dirichlet character of conductor 49 defined by \chi(3)=\zeta, for \zeta\ a primitive 42nd root of unity. We explicitly compute the slopes of the U_7 operator acting on the space of overconvergent modular forms on X_1(49) with weight k and character either \chi^{7k-6} or \chi^{8-7k}, depending on the embedding of Q(\zeta) into C_7. By applying results of Coleman, and of Cohen-Oesterl\'e, we are then able to conclude the slopes of U_7 acting on all classical Hecke newforms of the same weight and character.