Genres de Todd et valeurs aux entiers des dérivées de fonctions L

 
C. Soulé

 
 
  This is the manuscript of a Bourbaki talk in November 2005 about the arithmetic Lefschetz theorem of Kohler and Roessler and its use by Maillot and Roessler to prove cases of the Deligne-Gross conjecture about periods of motives with complex multiplication.
 
  Comments : All comments are welcome before March 2006, when the final version will be sent for publication.