  We calculate the one-loop matching coefficients between continuum and lattice
four-fermion operators for lattice operators constructed using staggered
fermions and improved by the use of fattened links. In particular, we consider
hypercubic fat links and SU(3) projected Fat-7 links, and their mean-field
improved versions. We calculate only current-current diagrams, so that our
results apply for operators whose flavor structure does not allow
``eye-diagrams''. We present general formulae, based on two independent
approaches, and give numerical results for the cases in which the operators
have the taste (staggered flavor) of the pseudo-Goldstone pion. We find that
the one-loop corrections are reduced down to the 10-20% level, resolving the
problem of large perturbative corrections for staggered fermion calculations of
matrix elements.
