  We have performed a dynamical analysis of the mixing in the pseudoscalar
channel with the goal of understanding the existence and behavior of the
pseudoscalar glueball. Our philosophy has not been to predict precise values of
the glueball mass but to exploit an adequate effective theory to the point of
breaking and to analyze which kind of mechanisms restore compatibility with
data. Our study has lead to analytical solutions which allow a clear
understanding of the phenomena. The outcome of our calculation leads to a large
mass glueball $M_\Theta>2000$ MeV, to a large glue content of the $\eta^\prime$
and to mixing angles in agreement with previous numerical studies.
