A joint 2- and 3-point clustering analysis of the VIPERS PDR2 catalogue
  at z~1: breaking the degeneracy of cosmological parameters
  We measure the galaxy 2- and 3-point correlation functions at $z=[0.5,0.7]$
and $z=[0.7, 0.9]$, from the final data release of the VIPERS survey (PDR2). We
model the two statistics including a nonlinear 1-loop model for the 2-point
function and a tree-level model for the 3-point function, and perform a joint
likelihood analysis. The entire process and nonlinear corrections are tested
and validated through the use of the 153 highly realistic VIPERS mock
catalogues, showing that they are robust down to scales as small as 10 $h^{-1}
\, \mathrm{Mpc}$. The mocks are also adopted to compute the covariance matrix
that we use for the joint 2- and 3-point analysis. Despite the limited
statistics of the two (volume-limited) sub-samples analysed, we demonstrate
that such a combination successfully breaks the degeneracy existing at 2-point
level between clustering amplitude $\sigma_8$, linear bias $b_1$ and the linear
growth rate of fluctuations $f$. For the latter, in particular, we measure
$f(z=0.61)=0.64^{+0.55}_{-0.37}$ and $f(z=0.8)=1.0\pm1.0$, while the amplitude
of clustering is found to be $\sigma_8(z=0.61)=0.50\pm 0.12$ and
$\sigma_8(z=0.8)=0.39^{+0.11}_{-0.13}$. These values are in excellent agreement
with the extrapolation of a Planck cosmology.
