  Surfaces corresponding to the constant values of the light front variable
forms paraboloids in the phase space of the inclusively produced hadrons in
heavy-ion collisions. In this paper, it is demonstrated with the simulated
Au-Au collisions at $\sqrt{s} = 200$ GeV using the UrQMD event generator that
the paraboloidal surface defined by a certain constant value of the light front
variable divides the particles in the phase space into two groups such that the
distributions of the square of the transverse momentum, the polar angle and the
light front variable of particles belonging to one among them can be described
with the Boltzmann distribution parameterised by the mass-dependent
temperature.
