The VII-th International Conference on the Initial Stages of High-Energy Nuclear Collisions : Initial Stages 2023

Two-particle transverse momentum correlations as a tool to assess viscous effects in pp, p–Pb, and Pb–Pb systems with the ALICE detector

Not scheduled

2h

Københavns Universitetsbibliotek Nord

Poster Collective dynamics from small to large systems Reception and poster session

Speaker

Victor Gonzalez (Wayne State University (US))

Description

Two-particle transverse momentum correlations enable measurements of the collision dynamics sensitive to momentum currents. Their evolution with collision multiplicity, as proxy of the system lifetime, gives information about the specific shear viscosity, $\eta/s$, and the system relaxation time, $\tau_{\pi}$.
In this talk, measurements of two-particle transverse momentum correlators in pp, p--Pb, and Pb--Pb collisions are presented. The strength and shape of the correlators are studied as functions of the particle multiplicity to find evidence for longitudinal broadening that might reveal the presence of viscous effects expected in fluid-like systems produced in these collisions. The measured correlators, their strengths and shapes, are additionally compared to model predictions. Their evolution, along the pp, p--Pb, and Pb--Pb systems, is discussed. Strong longitudinal broadening is observed in Pb--Pb collisions pointing to finite viscous effects. However, no significant broadening is observed in pp and p--Pb collisions, suggesting either no viscous effects in these systems or that they are too short-lived and small for frictional forces to affect the longitudinal width of the transverse momentum correlators.