Dijet imbalance measurements in $Au+Au$ and $pp$ collisions at $\sqrt{s_{NN}} = 200$ GeV at STAR

The collaboration
Phys.Rev.Lett. 119 (2017) 062301, 2017.

Abstract
We report the first di-jet transverse momentum asymmetry measurements from Au+Au and p+p collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly stronger momentum imbalance in heavy-ion collisions than in the p+p reference. When re-examined with correlated soft particles included, we observe that these di-jets then exhibit a unique new feature -- momentum balance is restored to that observed in p+p for a jet resolution parameter of R=0.4, while re-balancing is not attained with a smaller value of R=0.2.