Evidence for x-dependent proton color fluctuations in pA collisions at the LHC

We argue that the pattern of violation of the Glauber picture for centrality dependence of the rate of forward jet production observed in pA collisions at the LHC provides evidence that configurations in the proton containing a parton with large x_p interact with a significantly smaller than average cross section and have smaller than average size. Implementing effects of the fluctuations of the interaction strength and using the ATLAS analysis of the dependence of the hadron production at backward rapidities on the number of wounded nucleons, we make quantitative predictions for the centrality dependence of the jet production rate as a function of the interaction strength \sigma(x_p). For x_p=0.6 we find \sigma(x_p)\sim \sigma_{tot}(pp)/2 which sheds a light on the origin of the EMC effect.