Pseudoscalar glueball and $\eta-\eta^\prime$ mixing

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.