Forward- and Mid-Rapidity Jet-like correlations

Mid-rapidity azimuthal correlations probe di-jets originating mainly from gluon-gluon hard-scattering. Measurements of such correlations have revealed significant (gluon-)jet modification in central Au+Au collisions. Azimuthal correlations of hadrons at forward rapidity with a mid-rapidity high-$\text{pt}$ hadron, on the other hand, probe asymmetric partonic scatterings involving large-x quarks and small-x gluons. We present preliminary results from STAR on correlations of charged hadrons at forward rapidity in the forward TPCs ($2.7<\mathrm{\mid }\eta \mathrm{\mid }<3.9$, $\text{pt}<2$ GeV/$c$) with high-$\text{pt}$ charged hadrons at mid-rapidity from the main TPC ($\mathrm{\mid }\eta \mathrm{\mid }<1$, $\text{pt}>3$ GeV/$c$) in $pp$, d+Au, and Au+Au collisions at $\text{snn}=200$ GeV. The implications of the results for small-x gluon distributions (Color Glass Condensate formation) and the energy loss of quark jets at forward rapidity in nuclear medium are discussed. %Their measurements in d+Au collisions, separately at the d-side and the Au-side, may be sensitive to Color Glass Condensate in the Au-nucleus. Their measurements in Au+Au collisions may probe quark-jet modification in nuclear medium.