  Exotic mesons are striking predictions of quantum chromodynamics that go
beyond the quark model. They can provide great insight into understanding
phenomena such as asymptotic freedom, confinement, and dynamical symmetry
breaking. This work analyzes hadronic decays of exotic mesons, with a focus on
the lightest one, the $J^{PC}=1^{-+}$ $\pi_{1}$, in a fully relativistic
formalism. The relativistic spin wave functions of normal and exotic mesons are
constructed based on unitary representations of the Poincare group. The radial
wave functions are obtained from phenomenological considerations of the mass
operator. We find that fully relativistic results using Wigner rotations differ
significantly from nonrelativistic ones. Moreover, the S+P selection rule is
also satisfied in relativistic formalism. Final state interactions do not
change these results much.
