Untriggered di-hadron correlations in Pb-Pb collisions at $\sqrt{s_{NN}} =$ 2.76 TeV from ALICE

Understand

We present measurements of untriggered di-hadron correlations as a function of centrality in Pb-Pb \sNN collisions, for charged hadrons with $p_{T} > 0.15$ GeV$/c$.

• These measurements provide a map of the bulk correlation structures in heavy-ion collisions.
• Contributions to these structures may come from jets, initial density fluctuations, elliptic flow, resonances, and/or momentum conservation.
• We decompose the measured correlation functions via a multi-parameter fit in order to extract the nearside Gaussian, the longer range $\Delta \eta$ correlation often referred to as the soft ridge.