On motivic classes of moduli spaces of Higgs bundles, by Jochen Heinloth (Essen)br in Arithmetic, Motives and Moduli Spacesbr 9-13 January 2012br A conference organized by Olivier Debarre (ENS), Hélène Esnault (Essen), Claire Voisin (IMJ) et Olivier Wittenberg (ENS) on the occasion of the extended stay of Hélène Esnault, recipient of the Foundation's Chaire d'Excellence 2011.