Analytical result for dimensionally regularized massless on-shell double box

The dimensionally regularized massless on-shell double box Feynman diagram with powers of propagators equal to one is analytically evaluated for general values of the Mandelstam variables s and t. An explicit result is expressed either in terms of polylogarithms Lia−t/s, up to a=4, and generalized polylogarithms Sa,b(−t/s), with a=1,2 and b=2, or in terms of these functions depending on the inverse ratio, s/t.