  We analyze the effective triplet interactions between the centers of star
polymers in a good solvent. Using an analytical short distance expansion
inspired by scaling theory, we deduce that the triplet part of the three-star
force is attractive but only 11% of the pairwise part even for a close approach
of three star polymers. We have also performed extensive computer simulations
for different arm numbers to extract the effective triplet force. The
simulation data show good correspondence with the theoretical predictions. Our
results justify the effective pair potential picture even beyond the star
polymer overlap concentration.

Soft Condensed Matter