ar X iv : h ep - l at / 9 40 10 01 v 2 4 J an 1 99 4 1 Hadronic coupling constants in lattice QCD

We report on calculations of the hadronic coupling constants gρππ and gNNπ based on lattice QCD with four flavors of dynamical staggered fermions. By computing 2–point and 3–point Green's functions we have been able to determine these coupling constants ab initio from QCD; the results gρππ = 4.2 ± 1.8 and gNNπ = 14.8 ± 6 are compatible with the experimental values. Recent lattice QCD calculations of the had-ronic mass spectrum have given encouraging results , reproducing many of the experimental values even at a quantitative level. This motivates the launching of more complicated analyses such as the calculation of properties of the phenomeno-logical hadronic interactions. The aim of our work is a calculation of coupling constants which parameterize the strength of the interaction between hadrons at low energies. We have based the analysis on the staggered fermion action with four degenerate flavors of dy-namical fermions. The lattice size is 16 3 × 24 and we have generated so far 85 configurations at β = 5.35, m = 0.01 using the hybrid Monte Carlo algorithm. Details with respect to the production of configurations can be recalled from Ref.[1]. Hadronic Couplings in the Continuum Interactions between hadrons at low energies can be described by effective Lagrangians in which the hadrons enter as the " elementary particles " of the theory. The strength of the interaction is parameterized by effective coupling constants whose values have been determined by experiment. In our case the effective interaction Lagrangians are