2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/178837The dimensionally regularized massless double box Feynman diagram with powers of propagators equal to one, one leg off the mass shell, i.e. with non-zero q^2=p_1^2, and three legs on shell, p_i^2=0, i=2,3,4, is analytically calculated for general values of q^2 and the Mandelstam variables s and t. An explicit result is expressed through (generalized) polylogarithms, up to the fourth order, dependent on rational combinations of q^2,s and t, and a one-dimensional integral with a simple integrand consisting of logarithms and dilogarithms.10 pages, LaTeX with axodraw.sty, one reference is correctedHigh Energy Physics - PhenomenologyHigh Energy Physics - Theorytext