A&A 421, 23-40 (2004)
DOI: 10.1051/0004-6361:20040125
A new approach to gravitational clustering: A path-integral formalism and large-N expansions
P. ValageasService de Physique Théorique, CEN Saclay, 91191 Gif-sur-Yvette Cedex, France
(Received 20 June 2003 / Accepted 4 March 2004)
Abstract
We show that the formation of large-scale structures through gravitational instability in the expanding universe can be fully
described through a path-integral formalism. We derive the action
S[f] which gives the statistical weight associated with any phase-space distribution function
. This action
S describes both the average over the Gaussian initial conditions and the Vlasov-Poisson dynamics. Next, applying a standard
method borrowed from field theory we generalize our problem to an
N-field system and we look for an expansion over powers of
1/N. We describe three such methods and we derive the corresponding equations of motion at the lowest non-trivial order for the
case of gravitational clustering. This yields a set of non-linear equations for the mean
and the two-point correlation
G of the phase-space distribution
f, as well as for the response function
R. These systematic schemes match the usual perturbative expansion on quasi-linear scales but should also be able to treat
the non-linear regime. Our approach can also be extended to non-Gaussian initial conditions and may serve as a basis for other
tools borrowed from field theory.
Key words: cosmology: theory -- cosmology: large-scale structure of Universe
© ESO 2004
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