Analytical result for dimensionally regularized massless on-shell planar triple box

The dimensionally regularized massless on-shell planar triple box Feynman diagram with powers of propagators equal to one is analytically evaluated for general values of the Mandelstam variables s and t in a Laurent expansion in the parameter ϵ=(4−d)/2 of dimensional regularization up to a finite part. An explicit result is expressed in terms of harmonic polylogarithms, with parameters 0 and 1, up to the sixth order. The evaluation is based on the method of Feynman parameters and multiple Mellin–Barnes representation. The same technique can be quite similarly applied to planar triple boxes with any numerators and integer powers of the propagators.