Hypergeometric representation of a four-loop vacuum bubble
  In this article, we present a new analytic result for a certain single-mass-scale four-loop vacuum (bubble) integral. We also discuss its systematic $\e$-expansion in $d=4-2\e$ as well as $d=3-2\e$ dimensions, the coefficients of which are expressible in terms of harmonic sums at infinity. 
Ervin Bejdakic, York Schroder