An integral that occurs in particle physics might be
interesting to reduce. It is
ó õ
c
b
Ö
(d-t)(c-t)(t-b)(t-a)
dt
t
,
(1)
a special complete case of I(1,1,1,1,-1). For the integral to be
well defined, one assumes a < b < c < d. It is symmetric in some peculiar
combinations of a,b,c,d, and I once tried unsuccessfully to understand
why.