  To assess the properties of the quark-gluon plasma formed in heavy-ion
collisions, the ATLAS experiment at the LHC measures a correlation between the
mean transverse momentum and the magnitudes of the flow harmonics. The analysis
uses data samples of lead-lead and proton-lead collisions obtained at the
centre-of-mass energy per nucleon pair of 5.02 TeV, corresponding to total
integrated luminosities of $22 ~\mu b^{-1}$ and $28~nb^{-1}$, respectively. The
measurement is performed using a modified Pearson correlation coefficient with
the charged-particle tracks on an event-by-event basis. The modified Pearson
correlation coefficients for the $2^{nd}$-, 3$^{rd}$-, and 4$^{th}$-order
harmonics are measured as a function of event centrality quantified as the
number of charged particles or the number of nucleons participating in the
collision. The measurements are performed for several intervals of the
charged-particle transverse momentum. The correlation coefficients for all
studied harmonics exhibit a strong centrality evolution in the lead-lead
collisions, which only weakly depends on the charged-particle momentum range.
In the proton-lead collisions, the modified Pearson correlation coefficient
measured for the second harmonics shows only weak centrality dependence. The
data is qualitatively described by the predictions based on the hydrodynamical
model.
