Anisotropies in the initial energy density distribution of the
quark-gluon plasma created in high energy heavy ion collisions lead to
anisotropies in the azimuthal distributions of the final-state particles
known as collective anisotropic flow. Fourier harmonic decomposition is
used to quantify these anisotropies. The higher-order harmonics can be
induced by the same order anisotropies (linear response) or by the
combined influence of several lower order anisotropies (nonlinear
response) in the initial state. The mixed highe-rorder anisotropic flow
and nonlinear response coefficients of charged particles are measured as
functions of transverse momentum and centrality in PbPb collisions at
nucleon-nucleon center-of-mass energies root s(NN) = 2.76 and 5.02 TeV
with the CMS detector. The results are compared with viscous
hydrodynamic calculations using several different initial conditions,
aswell asmicroscopic transport model calculations. None of the models
provides a simultaneous description of the mixed higher-order flow
harmonics and nonlinear response coefficients