$\Delta \eta$-$\Delta \varphi$ correlations and the ridge structure in STAR

Abstract

Triggered di-hadron correlation studies using central Au+Au collisions at $\sqrt{S_{NN}}$ = 200 GeV in STAR revealed a novel ridge-like structure in two dimensions ($\Delta \eta$,$\Delta \varphi$) for high $p_T$ particles. A similar structure is also present in an inclusive un-triggered di-hadron correlation analysis. We study the <$p_T$> evolution of di-hadron correlations by increasing the lower $p_T$ acceptance of both charged particles. A smooth evolution of data is observed and our results reproduce the triggered analysis structure near <p_{T}> = 2.7 GeV/c. We quantify the correlation structure evolution by fitting a model function. The model function emphasizes possible initial state fluctuation contributions via the use of higher harmonic model components $v_n$ (n=1,2,3,4,5) and a remainder which is modeled via an asymmetric 2d Gaussian. The extracted parameters are compared to model predictions and p+p data at $\sqrt{S_{NN}}$ = 200 GeV and possible origins of the nearside structure are discussed.

8 Pages, 7 Figures : Proceedings of the Winter Workshop in Nuclear Dynamics, Puerto Rico

References in corpus (4)

• Collision geometry fluctuations and triangular flow in heavy-ion collisions
• Long Range Correlations and the Soft Ridge in Relativistic Nuclear Collisions
• Intra-jet correlations of high-$p_t$ hadrons from STAR
• Jets, Mach cone, hot spots, ridges, harmonic flow, dihadron and $\gamma$-hadron correlation in high-energy heavy-ion collisions