  It is shown that the $\mu^{\pm}$ originating from the decay of heavy-flavour
mesons in the simulated proton-proton collisions at $\sqrt{s} = 13$ TeV using
the PYTHIA 8 event generator can be made into two groups based on the value of
their light front variable such that one among these two groups of $\mu^{\pm}$
follow the Boltzmann statistics with a nearly isotropic angular distribution. A
similar effect is not observed for $e^{\pm}$ from the decay of heavy-flavour
mesons in these collisions.
