The asymptotic behaviour of the ${\pi }^0$ ${\gamma }^{\ast }$ ${\gamma }^{\ast }$ vertex

J. -M. Gérard, T. Lahna

The Bjorken-Johnson-Low theorem applied to the ${\gamma }^{\ast }\to {\gamma }^{\ast }{\pi }^0$ process provides us with a rather remarkable asymptotic behaviour for the ${\pi }^0{\gamma }^{\ast }{\gamma }^{\ast }$ vertex. We comp…