A Lorentz-covariant regularization scheme for effective field theories with an arbitrary number of propagating heavy and light particles is given. This regularization scheme leaves the low-energy analytic structure of Greens functions intact and preserves all the symmetries of the underlying Lagrangian. The power divergences of regularized loop integrals are controlled by the low-energy kinemat...

We examine the role of the ∆∆ intermediate state in NN scattering in the S0 channel. The computation is performed at lowest order in an effective field theory involving local four-fermion operators and one pion exchange using dimensional regularization with MS. As first discussed by Weinberg, in the theory with only nucleons the large scattering length in this channel requires a small scale for...

The basic idea behind effective field theory (EFT) methods is to describe nature in terms of a fully consistent quantum field theory, but one which is valid in a limited energy range. Now strictly speaking this means that almost any theory is an EFT except string theories that try to be a theory of everything (TOE). Indeed even the quintessential quantum field theory—quantum electrodynamics—is ...