# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## Observation of identical "near-side" jet-like correlations in d+Au and Au+Au collisions at low trigger $p_T$ by STAR

16 Aug 2012, 16:00
2h

Poster Jets

Joshua Konzer

### Description

Particle production mechanisms vary with $p_T$. At low $p_T$ soft processes dominate whereas hard processes dominate at higher $p_T$. Experimental data has shown drastic change from d+Au to Au+Au collision in $p_T$ spectra, collective phenomena, and baryon/meson ratio at intermediate $p_T$. This indicates that the relative mixture of particles produced by hard and soft processes differ between Au+Au and d+Au at a given, relatively low $p_T$ (< 2.0GeV). It is therefore expected that the dihadron correlations will differ between d+Au and Au+Au with relatively low trigger particle $p_T$. In this talk we present the near-side jet-like correlations in d+Au and Au+Au collisions at 200 GeV by STAR. The jet-like results are obtained by the difference of small and large \Delta\eta correlations. We report the findings as a function of trigger and associated particle $p_T$, collision centrality, and Event Plane trigger orientation. We find the $/sqrt{S_{NN}}=200$GeV d+Au and Au+Au near-side correlations to be identical even at trigger $p_T$ as low as 1.5 GeV/c. The AMPT and HIJING models do not describe the data. Our results seem to challenge the current understanding of particle production mechanisms in relativistic heavy-ion collisions.

### Presentation Materials

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