%0 Journal Article %A Dennis Gaitsgory %A David Nadler %T Hecke operators on quasimaps into horospherical varieties %J Documenta mathematica %D 2009 %P 19-46 %V 14 %U http://geodesic.mathdoc.fr/articles/10.4171/dm/264/ %R 10.4171/dm/264 %F 10_4171_dm_264