Bold, Tomasz
(2021)
Correlation of flow harmonics and mean transverse momentum in 5.02 TeV p plus Pb and Pb plus Pb collisions and event-plane dependence of HBT radii in high-multiplicity p plus Pb collisions
NUCLEAR PHYSICS A, 1005.
121826-.
ISSN 0375-9474, 1873-1554
Abstract
To assess the properties of the quark-gluon plasma formed in heavy ion collisions, correlations between the mean transverse momentum, [p T], and the magnitude of the flow harmonics, ν n , are measured by the ATLAS experiment at the LHC. The analysis uses data samples of Pb+Pb and p+Pb collisions at s NN = 5.02 TeV , corresponding to integrated luminosities of 22 μb−1 and 28 nb−1, respectively. The correlations are measured using a modified Pearson coefficient that is independent of multiplicity fluctuations. To suppress any short-range correlations, the [p T] is measured at mid-rapidity and the flow harmonics are measured at forward rapidity. In Pb+Pb collisions, significant (non-zero) values of the correlation coefficients are observed for all studied harmonics, which show a strong centrality dependence but vary only weakly with the charged particle p T range used in the measurement. On the other hand, in p+Pb collisions, the correlation coefficient measured for the 2 nd harmonic is found to show only a weak centrality dependence. The predictions of a 3+1D viscous-hydrodynamic model are found to be qualitatively consistent with the data, indicating hydrodynamic origin of these correlations in p+Pb collisions. As an independent test for the hydrodynamic description of collectivity observed in p+Pb collisions, measurements of two-pion HBT correlations as a function of the angle of the pion pair with respect to the second-order event plane angle are presented. The HBT correlation functions, corrected for event plane resolution, are measured as a function of q out, q side and q long in intervals of pair transverse momentum and second-order flow-vector magnitude. The correlation functions are fit using the Bowler-Sinyukov form with the exponential HBT correlation function. The extracted HBT radii, R out, R side and R long and a significant out-side cross-term are found to exhibit significant modulation with respect to the second-order event plane, similar to that observed in heavy-ion collisions. Results of the measurements and physics implications of the result, will be discussed.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | flow, correlations, HBT, interferometry |
| Divisions: | Faculty of Science & Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 30 May 2022 13:31 |
| Last Modified: | 16 Jun 2026 07:36 |
| DOI: | 10.1016/j.nuclphysa.2020.121826 |
| Open Access URL: | https://cds.cern.ch/record/2707851 |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3155711 |
| Disclaimer: | The University of Liverpool is not responsible for content contained on other websites from links within repository metadata. Please contact us if you notice anything that appears incorrect or inappropriate. |
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