The joint analysis of clustering and stacked gravitational lensing of galaxy clusters in large surveys can constrain the formation and evolution of structures and the cosmological parameters .
On scales outside a few virial radii , the halo bias , b , is linear and the lensing signal is dominated by the correlated distribution of matter around galaxy clusters .
We discuss a method to measure the power spectrum amplitude \sigma _ { 8 } and b based on a minimal modelling .
We considered a sample of \sim 120000 clusters photometrically selected from the Sloan Digital Sky Survey in the redshift range 0.1 < z < 0.6 .
The auto-correlation was studied through the two-point function of a subsample of \sim 70000 clusters ; the matter-halo correlation was derived from the weak lensing signal of the subsample of \sim 1200 clusters with Canada-France-Hawaii Lensing Survey data .
We obtained a direct measurement of b , which increases with mass in agreement with predictions of the \Lambda CDM paradigm .
Assuming \Omega _ { \mathrm { M } } = 0.3 , we found \sigma _ { 8 } = 0.78 \pm 0.16 .
We used the same clusters for measuring both lensing and clustering and the estimate of \sigma _ { 8 } did require neither the mass-richness relation , nor the knowledge of the selection function , nor the modelling of b .
With an additional theoretical prior on the bias , we obtained \sigma _ { 8 } = 0.75 \pm 0.08 .