title: Dihedral congruence primes and class fields of real quadratic fields
abstract: We show that for a real quadratic field F the dihedral congruence primes with respect to F for cusp forms of weight k and quadratic nebentypus are essentially the primes dividing expressions of the form epsilon /sub +//sup k-1/+or-1 where epsilon /sub +/ is a totally positive fundamental unit of F. This extends work of Hida. Our results allow us to identify a family of (ray) class fields of F which are generated by torsion points on modular abelian varieties
keyphrases: dihedral congruence primes class fields real quadratic fields quadratic nebentypus torsion points modular abelian varieties class field theory