<< MB.m

<< AMBRE.m

B4l2m = 
        Fullintegral[{k1*p1, k1*p2, 
            k1*p3}, {PR[k1, m, n1] PR[k1 + p1, 0, n2] PR[k1 + p1 + p2, m, n3] 
              PR[k1 + p3, 0, n4]}, {k1}];
invariants = {(p1^2) -> (m^2), (p2^2) -> (m^2), 
          (p3^2) -> (m^2), p4^2 -> m^2, 
          p1 p2 -> -(m^2) + (s/2), p1 p3 -> (m^2) - (t/2), 
          p1*p4 -> s/2 + t/2 - m^2, 
          p2 p3 -> -(m^2) + (s/2) + (t/2), 
          p2*p4 -> -t/2 + m^2, 
          p3*p4 -> s/2 - m^2};

IntPart[1]

repr = SubLoop[integral];

fin = Simplify[
            ARint[1, #] /. {n1 -> 1, n2 -> 1, n3 -> 1, 
                n4 -> 1}] & /@ repr

fin = BarnesLemma[#, 1] & /@ fin;

integrals = MBcontinue[#, eps -> 0, 
              MBoptimizedRules[#, eps -> 0, {}, {eps}], 
              Verbose -> False] & /@ fin;

ser = MBexpand[{#}, Exp[eps EulerGamma], {eps, 0, 1}] & /@ 
          integrals;

num = 
      Plus  @@  (MBintegrate[#, {s -> -1/2, t -> -7, 
                  m -> 1}, Verbose -> False] & /@ 
            ser)