Glueball as a bound state in the self-dual homogeneous gluon field
  Using a simple relativistic QFT model of scalar fields we demonstrate that the analytic confinement (propagator is an entire function in the complex $p^2$--plane) and the weak coupling constant lead to the Regge behaviour of the two-particle bound states. In QCD we assume that the gluon vacuum is realized by the self-dual homogeneous classical field which is the solution of the Yang-Mills equations. This assumption leads to analytical confinement of quarks and gluons. We extract the colorless $0^{++}$ two-gluon state from the QCD generating functional in the one-gluon exchange approximation. The mass of this bound state is defined by the Bethe-Salpeter equation. The glueball mass is $1765~{\rm MeV}$ for $\alpha_s=0.33$ if the gluon condensate is $<(\alpha_s/\pi) G G >=0.012~{\rm GeV}^4$. 
Ja.V. Burdanov, G.V. Efimov