Systematic study of flow vector decorrelation in {s_{ ₍₍}=5. 02} TeV Pb-Pb collisions

Measurements of the p ₓ-dependent flow vector fluctuations in Pb-Pb collisions at s_ ₍₍ = 5. 02~TeV using azimuthal correlations with the ALICE experiment at the LHC are presented. A four-particle correlation approach 1 is used to quantify the effects of flow angle and magnitude fluctuations separately. This paper extends previous studies to additional centrality intervals and provides measurements of the p ₓ-dependent flow vector fluctuations at s_ ₍₍ = 5. 02~TeV with two-particle correlations. Significant p ₓ-dependent fluctuations of the V₂ flow vector in Pb-Pb collisions are found across different centrality ranges, with the largest fluctuations of up to 15% being present in the 5% most central collisions. In parallel, no evidence of significant p ₓ-dependent fluctuations of V₃ or V₄ is found. Additionally, evidence of flow angle and magnitude fluctuations is observed with more than 5 significance in central collisions. These observations in Pb-Pb collisions indicate where the classical picture of hydrodynamic modeling with a common symmetry plane breaks down. This has implications for hard probes at high p ₓ, which might be biased by p ₓ-dependent flow angle fluctuations of at least 23% in central collisions. Given the presented results, existing theoretical models should be re-examined to improve our understanding of initial conditions, quark--gluon plasma (QGP) properties, and the dynamic evolution of the created system.