The $\eta NN$ coupling constant

Abstract

We derive the light cone QCD sum rule for the $\eta NN$ coupling constant $g_{\eta NN} $. The contribution from the excited states and the continuum is subtracted cleanly through the double Borel transform with respect to the two external momenta, $p_1^2$, $p_2^2=(p-q)^2$. Our result is $\alpha_{\eta NN}=(0.3\pm 0.15)$, which favors small values used in literatures.