Hidden conformal symmetry of a massive scalar field in 2-dimensional   Anti-De Sitter space
  We show that a massive scalar field on a 2-dimensional Anti-De Sitter space can be mapped by means of a time-dependent canonical transformation into a massless free field theory when the mass square of the field is equal to minus the curvature of the background metric. We also provide the (hidden) conformal symmetry of the massive scalar field. 
J. Cruz (MIT-CTP)