NBI Heavy-ion Physics Junior Seminar: Correlation between spatial and momentum anisotropies suggesting hydrodynamic evolution in high-energy collisions at the LHC
NBB 2.4.G.092
NBI
Title: Correlation between spatial and momentum anisotropies suggesting hydrodynamic evolution in high-energy collisions at the LHC
Speaker: Wenya Wu (Technische Universität München)
Abstract:
Evidence for partonic collectivity has been observed in both large (Pb-Pb) and small (pp and p-Pb) collision systems at the LHC through measurements of the transverse-momentum-differential elliptic flow of identified particles. In particular, the characteristic baryon-meson grouping pattern, compared with theoretical models, suggests that quark-coalescence hadronization exists across different collision systems. The hot and dense matter created in these high-energy collisions is widely regarded as a nearly perfect fluid and can be described successfully by hydrodynamic models. As a key observable characterizing azimuthal anisotropy in the transverse plane, the flow coefficient reflects the initial-state geometry and the subsequent transport evolution of the system.
At the same time, spatial information about the particle-emitting source at the final stage can be accessed through femtoscopic momentum correlations. By combining three-dimensional femtoscopic source measurements relative to the event plane with elliptic-flow studies using the event-shape-engineering technique, one can investigate the interplay between the spatial geometry of the source at freeze-out and the momentum-space anisotropy of final-state particles, thereby studying the hydrodynamic collectivity of the system. Recent analyses show that the radii Rside and Rout, measured as functions of the azimuthal angle with respect to the event plane in different v2 classes, exhibit larger oscillation amplitudes in events with stronger elliptic flow. These results demonstrate how collective flow influences the spatial geometry at freeze-out, providing new constraints on the dynamical coupling between geometry and collective expansion.