System size and event shape dependence of the mean transverse momentum fluctuations with ALICE at the LHC

Measurement of the event-by-event fluctuations of the mean transverse momentum, ⟨ p T ⟩, helps to characterize the properties of the bulk of the system created in ultrarelativistic heavy-ion collisions, called the quark-gluon plasma (QGP). The fluctuations are closely related to the dynamics of the phase transition from the QGP to a hadron gas. Here, the ⟨ p T ⟩ fluctuations of charged particles produced in pp, Xe–Xe and Pb–Pb collisions at the LHC are discussed. The fluctuations are measured via the integral correlator, ⟨⟨Δ p T Δ p T ⟩⟩. The strength of the correlator is found to decrease monotonically with increasing charged-particle multiplicity measured at mid-rapidity in all three systems. The correlation strength is also studied in pp collisions by classifying the events based on their event shape, transverse spherocity.