Collective behavior in small systems

Abstract:

The presence of correlations between particles significantly separated in pseudorapidity in proton-proton and proton-nucleus collisions has raised questions about whether collective effects are observed in small collision systems as well as in heavy-ion collisions. The quantification of these long-range correlations by v_n coefficients is of particular interest. A selection of the latest v_n measurements is presented, including results from the recent d+Au beam energy scan at RHIC where a significant non-zero v₂ is measured down to low center-of-mass energies (√s_NN = 39 TeV). Results from a collision system scan – comprising p+Au, d+Au, and ³He+Au collisions – are also shown to address the role of the initial nuclear geometry in the final state anisotropy. Finally, the challenge of measuring multi-particle cumulants, particularly c₂{4}, in p+p collisions is discussed, and new methods for reducing the effects of non-flow are shown to produce a more robust measurement of v₂{4} in p+p collisions.

A. Ohlson: Collective behavior in small systems, Nucl. Phys. A 967 (2017) 97

https://doi.org/10.1016/j.nuclphysa.2017.06.023

Related to Project A01, A02, A03, A04, C06