  We study all-charm tetraquarks in the front form of Hamiltonian dynamics
using the many-body basis function approach known as basis light-front
quantization. The model Hamiltonian contains transverse and longitudinal
confining potentials and a one-gluon-exchange effective potential. We calculate
masses of two-charm-two-anticharm states focusing on the lowest state. We also
calculate two-quark and four-quark estimates of meson-meson breakup threshold.
The results suggest that the lowest two-charm-two-anticharm state is not a
tightly bound tetraquark. We discuss implications of the cluster decomposition
principle for theories formulated on the light front and present our treatment
of identical particles together with color-singlet restrictions on the space of
quantum states.
