  We have detected non-Gaussian signatures in the VIRMOS-DESCART weak lensing
survey from a measurement of the three-point shear correlation function,
following the method developed by Bernardeau et al. (2002). We obtain a
2.4-sigma signal over four independent angular bins, or equivalently, a
4.9-sigma confidence level detection with respect to measurements errors on
scale of about 2 to 4 arcmin. The amplitude and the shape of the signal are
consistent with theoretical expectations obtained from ray-tracing simulations.
This result supports the idea that the measure corresponds to a cosmological
signal due to the gravitational instability dynamics. Its properties could be
used to put constraints on the cosmological parameters, in particular on the
density parameter of the Universe, but the error level as well as the cosmic
variance are still too large to permit secure conclusions.
