Energy dependence of dissociative $\mathrm{J/}\psi$ 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 $\mathrm{J/}\psi$ photoproduction data from H1 and ALICE. Our model predicts that for $W_{\gamma\mathrm{p}} \approx 500$ GeV, the dissociative $\mathrm{J/}\psi$ cross section reaches a maximum and then decreases steeply with energy, which is in qualitatively good agreement to a recent observation that the dissociative $\mathrm{J/}\psi$ background in the exclusive $\mathrm{J/}\psi$ sample measured in photoproduction by ALICE decreases as energy increases. Our prediction provides a clear signature for gluon saturation at LHC energies. 
J. Cepila (1), J. G. Contreras (1) and J. D. Tapia Takaki (2) ((1)   Faculty of Nuclear Sciences and Physical Engineering, C...
hep-ph