The scalar box integral and the Mellin - Barnes representation
  We solve exactly the scalar box integral using the Mellin-Barnes representation. Firstly we recognize the hypergeometric functions resumming the series coming from the scalar integrals, then we perform an analytic continuation before applying the Laurent expansion in^2 = (d !' 4)=2 of the result. 
Paolo Valtancoli
math-ph hep-th math.MP