  We study the interaction of scalar glueball with quark-antiquark and
four-quark spinless meson fields within the framework of a generalized linear
sigma model in which the trace anomaly of QCD is exactly realized. To determine
the pure scalar glueball mass ($m_h$), we consider the decoupling limit in
which the scalar glueball decouples from the meson fields. We find the exact
relationship $m_h = 2\, h_0$ where $h_0$ is the vacuum expectation value of the
scalar glueball field independent of the properties of the framework used.
