A Lagrangian effective field theory
  We have continued the development of Lagrangian, cosmological perturbation
theory for the low-order correlators of the matter density field. We provide a
new route to understanding how the effective field theory (EFT) of large-scale
structure can be formulated in the Lagrandian framework and a new resummation
scheme, comparing our results to earlier work and to a series of
high-resolution N-body simulations in both Fourier and configuration space. The
`new' terms arising from EFT serve to tame the dependence of perturbation
theory on small-scale physics and improve agreement with simulations (though
with an additional free parameter). We find that all of our models fare well on
scales larger than about two to three times the non-linear scale, but fail as
the non-linear scale is approached. This is slightly less reach than has been
seen previously. At low redshift the Lagrangian model fares as well as EFT in
its Eulerian formulation, but at higher $z$ the Eulerian EFT fits the data to
smaller scales than resummed, Lagrangian EFT. All the perturbative models fare
better than linear theory.
