For the first time, correlations among mixed-order moments of two or three flow harmonics —(vkn,vlm) and (vkn, vlm, vqp), with k, l, and q denoting the respective orders—are measured in xenon–xenon (XeXe) collisions
and compared with lead–lead (PbPb) results, providing a novel probe of collective behavior in heavy ion colli
sions. These measurements compare a nearly spherical, doubly-magic 208Pb nucleus to a triaxially deformed 129Xe
nucleus, emphasizing the sensitivity to initial-state geometry fluctuations arising from nuclear deformation. The
dependence of these results (vn, n = 2,3,4) on the shape and size of the nuclear overlap region is studied. Comparisons between v2, v3, and v4
demonstrate the importance of v3 and v4 in exploring the nonlinear hydrodynamic
response of the quark-gluon plasma (QGP) to the initial spatial anisotropy. The results constrain initial-state
model parameters that influence the evolution of the QGP. The CMS detector was used to collect XeXe and PbPb
data at nucleon-nucleon center-of-mass energies of √SNN =5.44 and 5.36 TeV, respectively. Correlations are
extracted using multiparticle mixed-harmonic cumulants (up to eight-particle cumulants) wi
