Higgs- and Goldstone-boson-mediated long range forces

In certain mild extensions of the standard model, spin-independent long range forces can arise by exchange of two very light pseudoscalar spin-0 bosons. In particular, we have in mind models in which these bosons do not have direct tree level couplings to ordinary fermions. Using the dispersion theoretical method, we find a ${1/r}^3$ behavior of the potential for the exchange of very light pseudoscalars and a ${1/r}^7$ dependence if the pseudoscalars are true massless Goldstone bosons.