Why does quark-gluon plasma resist flow in strange ways?

Quark-gluon plasma — the soup of quarks and gluons briefly created in heavy-ion collisions — flows with nearly zero viscosity near the crossover temperature where it forms, then rises again, a behavior no simple model captures cleanly. By adding a curvature-squared 'Gauss-Bonnet' correction to a holographic QCD framework and letting it depend on the background field, the authors reproduce this non-monotonic viscosity profile while matching lattice QCD thermodynamics and placing the predicted critical end point of the QCD phase diagram squarely in the experimentally relevant range.