Energy dependence of dissociative J/ψ photoproduction as a signature of gluon saturation at the LHC

We have developed a model in which the quantum fluctuations of the proton structure are characterised by hot spots, whose number grows with decreasing Bjorken-x. Our model reproduces the F 2 (x, Q 2 ) data from HERA at the relevant scale, as well as the exclusive and dissociative J/ photoproduction data from H1 and ALICE. Our model predicts that for W p 500 GeV, the dissociative J/ cross section reaches a maximum and then decreases steeply with energy, which is in qualitatively good agreement to a recent observation that the dissociative J/ background in the exclusive J/ sample measured in photoproduction by ALICE decreases as energy increases. Our prediction provides a clear signature for gluon saturation at LHC energies.