The European Physical Journal C > 2017 > 77 > 6 > 1-40
Measurement of multi-particle azimuthal correlations in pp, p + Pb and low-multiplicity Pb + Pb collisions with the ATLAS detector
Source
Abstract
Multi-particle cumulants and corresponding Fourier harmonics are measured for azimuthal angle distributions of charged particles in $$pp$$ p p collisions at $$\sqrt{s}$$ s = 5.02 and 13 TeV and in $$p$$ p + Pb collisions at $$\sqrt{s_{_\text {NN}}}$$ s NN = 5.02 TeV, and compared to the results obtained for low-multiplicity $$\mathrm{Pb}~+~\mathrm{Pb}$$ Pb + Pb collisions at $$\sqrt{s_{_\text {NN}}}$$ s NN = 2.76 TeV. These measurements aim to assess the collective nature of particle production. The measurements of multi-particle cumulants confirm the evidence for collective phenomena in $$p$$ p + Pb and low-multiplicity $$\mathrm{Pb}~+~\mathrm{Pb}$$ Pb + Pb collisions. On the other hand, the $$pp$$ p p results for four-particle cumulants do not demonstrate collective behaviour, indicating that they may be biased by contributions from non-flow correlations. A comparison of multi-particle cumulants and derived Fourier harmonics across different collision systems is presented as a function of the charged-particle multiplicity. For a given multiplicity, the measured Fourier harmonics are largest in $$\mathrm{Pb}~+~\mathrm{Pb}$$ Pb + Pb , smaller in $$p$$ p + Pb and smallest in $$pp$$ p p collisions. The $$pp$$ p p results show no dependence on the collision energy, nor on the multiplicity.
Identifiers
journal ISSN : | 1434-6044 |
journal e-ISSN : | 1434-6052 |
DOI | 10.1140/epjc/s10052-017-4988-1 |