Point counting on reductions of CM elliptic curves
arXiv:0706.3711 · doi:10.1016/j.jnt.2009.01.020
Abstract
We give explicit formulas for the number of points on reductions of elliptic curves with complex multiplication by any imaginary quadratic field. We also find models for CM -curves in certain cases. This generalizes earlier results of Gross, Stark, and others.
Minor corrections. To appear in Journal of Number Theory