Lagrangian perturbations and the matter bispectrum II: the resummed
  one-loop correction to the matter bispectrum
  This is part two in a series of papers in which we investigate an approach
based on Lagrangian perturbation theory (LPT) to study the non-linear evolution
of the large-scale structure distribution in the universe. Firstly, we compute
the matter bispectrum in real space using LPT up one-loop order, for both
Gaussian and non-Gaussian initial conditions. In the initial position limit, we
find that the one-loop bispectrum computed in this manner is identical to its
counterpart obtained from standard Eulerian perturbation theory (SPT).
Furthermore, the LPT formalism allows for a simple reorganisation of the
perturbative series corresponding to the resummation of an infinite series of
perturbations in SPT. Applying this method, we find a resummed one-loop
bispectrum that compares favourably with results from N-body simulations. We
generalise the resummation method also to the computation of the redshift-space
bispectrum up to one loop.
