  The mass components of charmonium(-like) states are investigated through the
decomposition of QCD energy-momentum tensor (EMT) on lattice. The quark mass
contribution $\langle H_m\rangle$ and the momentum fraction $\langle x\rangle$
of valence charm quark and antiquark are calculated for conventional $1S,1P,1D$
charmonia and the exotic $1^{-+}$ charmonium-like state, based on the $N_f=2+1$
gauge configurations generated by the RBC/UKQCD collaboration. It is found that
$\langle H_m\rangle$ is around 2.0 to 2.2 GeV for these states, which implies
that the mass splittings among these states come almost all from the
contribution of QCD anomaly and ultimately the gluon contribution. The $\langle
x\rangle$ of the $1^{-+}$ state is only around 0.55, while that in conventional
charmonia is around 0.7 to 0.8. This difference manifests that the proportion
of light quarks and gluons in the $1^{-+}$ charmonium-like state is
significantly larger than conventional states.
