Jul 4 – 11, 2018
Asia/Seoul timezone

Recent results on correlations and fluctuations in pp, p+Pb, and Pb+Pb collisions from the ATLAS Experiment at the LHC

Jul 6, 2018, 5:42 PM
105 (COEX, Seoul)


COEX, Seoul

Parallel Heavy Ions Heavy Ions


Mariusz Przybycien (AGH University of Science and Technology (PL))


The azimuthal anisotropies of particle yields observed in relativistic
heavy-ion collisions have been traditionally considered as a strong
evidence of the formation on a deconfined quark-gluon plasma produced in
these collisions. However multiple recent measurements from the ATLAS
Collaboration in pp and p+Pb systems show similar features as those
observed in Pb+Pb collisions, indicating the possibility of the
production of such a deconfined medium in smaller collision systems.
This talk presents a comprehensive summary of ATLAS measurements in pp
collisions at 2.76, 5.02 and 13~TeV and in p+Pb collisions at 5.02 and
8.16 TeV. It includes measurements of two-particle hadron-hadron and
muon-hadron correlations in Δϕ and Δη, with a template fitting procedure
used to subtract the dijet contributions. Measurements of multi-particle
cumulants c_n{2−8} are also presented. The standard cumulant
measurements confirm presence of collective phenomena in p+Pb
collisions, but are biased by non-flow correlations and are not able to
provide evidence for collectivity in pp collisions. To address this,
measurements from a new sub-event cumulant method that suppresses the
contribution of non-flow effects are presented. More detailed studies
of longitudinal flow decorrelations, and higher-order cumulants in
ultra-central Pb+Pb collisions are also presented to provide deeper
insight into the details of the geometry of the initial state.

Primary authors

The ATLAS Collaboration Mariusz Przybycien (AGH University of Science and Technology (PL))

Presentation materials