Strangeness Enhancement in Cu+Cu and Au+Au Collisions at $\sqrt{s_{NN}} = 200$ GeV
Phys.Rev.Lett. 108 (2012) 072301, 2012.
The collaboration

Abstract (data abstract)
BNL-RHIC. We report new STAR measurements of mid-rapidity yields for the $\Lambda$, $\bar{\Lambda}$, $K^0_S$, $\Xi^-$, $\bar{\Xi}^+$, $\Omega^-$, $\bar{\Omega}^+$ particles in Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV, and mid-rapidity yields for the $\Lambda$, $\bar{\Lambda}$, $K^0_S$ particles in Au+Au at $\sqrt{s_{NN}} = 200$ GeV. We show that at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parameterization based on the fraction of participants that undergo multiple collisions.