A $QQ\to QQ$ planar doublebox in canonical form
  We consider a planar doublebox with four massive external momenta and two massive internal propagators. We derive the system of differential equations for the relevant master integrals, cast it in canonical form, write it as a $d\log$ form and solve it in terms of iterated integrals up to depth four. 
Marco S. Bianchi, Matias Leoni
hep-ph