The strong $\rho NN$ coupling derived from QCD

Abstract

We study the two point correlation function of two nucleon currents sandwiched between the vacuum and the rho meson state. The light cone QCD sum rules are derived both for $\rho NN$ vector and tensor couplings simultaneously. 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 results are $g_\rho =(2.5\pm 0.2)$, $\kappa_\rho =(8.0\pm 2.0), in good agreement with the values used in the nuclear forces.