  Hybrid mesons are exotic mesons in which the color field is not in the ground
state. Their understanding deserves interest from a theoretical point of view,
because it is intimately related to nonperturbative aspects of QCD. Moreover,
it seems that some recently detected particles, such as the $\pi_1(1600)$ and
the Y(4260), are serious hybrid candidates. In this work, we investigate the
description of such exotic hadrons by applying the auxiliary fields technique
to the widely used spinless Salpeter Hamiltonian with appropriate linear
confinement. Instead of the usual numerical resolution, this technique allows
to find simplified analytical mass spectra and wave functions of the
Hamiltonian, which still lead to reliable qualitative predictions. We analyse
and compare two different descriptions of hybrid mesons, namely a two-body
$q\bar q$ system with an excited flux tube, or a three-body $q\bar q g$ system.
We also compute the masses of the $1^{-+}$ hybrids. Our results are shown to be
in satisfactory agreement with lattice QCD and other effective models.
