  We study the propagator of a colored scalar particle in the background of a
non-abelian gauge field using the worldline formalism. It is obtained by
considering the open worldline of a scalar particle with extra degrees of
freedom needed to take into account the color charge of the particle, which we
choose to be in the fundamental representation of the gauge group. Specializing
the external gauge field to be given by a sum of plane waves, i.e. a sum of
external gluons, we produce a master formula for the scalar propagator with an
arbitrary number of gluons directly attached to the scalar line, akin to
similar formulas derived in the literature for the case of the scalar particle
performing a loop. Our worldline description produces at the same time the
situation in which the particle has a color charge given by an arbitrarily
chosen symmetric or antisymmetric tensor product of the fundamental.
