  We study the mass/energy structure of the bound state of hadrons in
two-dimensional quantum chromodynamics in the large number of color limit (t'
Hooft model). We analyze separately the contributions from the traceless and
trace part of the energy-momentum tensor, and show that the masses are related
to the matrix elements of the scalar charge and Coulomb energy. We derive the
light-front sum rules for the scalar charge and Coulomb energy, expressed in
terms of the light-front wave functions, and find that they are regular at
$x=0$ without the delta function contribution. We also consider the result for
the massless Goldstone boson, as well as the structure of the gravitational
form factors of the bound meson states.
