We discuss the associated $cbar{c}$ and $l^+l^-$ pairs production in ultraperipheral heavy-ion collisions at high energies. Such a channel provides a novel probe for double-parton scattering (DPS) at small $x$ enabling one to probe the photon density
inside the nucleus. We have derived an analog of the standard central $pp$ pocket formula and studied the kinematical dependence of the effective cross section. Taking into account both elastic and non-elastic contributions, we have shown predictions for the DPS $cbar c l^+l^-$ production cross section differential in charm quark rapidity and dilepton invariant mass and rapidity for LHC and a future collider.
In this paper, we study fully differential quarkonia photoproduction observables in ultraperipheral collisions (UPCs) as functions of momentum transfer squared. We employ the dipole picture of the QCD part of the scattering with proton and nucleus ta
rgets, with the projectile being a quasi-real photon flux emitted by an incoming hadron. We analyse such observables for ground $J/psi$, $Upsilon(1S)$ and excited $psi$, $Upsilon(2S)$ states whose light-front wave functions are obtained in the framework of interquark potential model incorporating the Melosh spin transformation. Two different low-$x$ saturation models, one obtained by solving the Balitsky--Kovchegov equation with the collinearly improved kernel and the other with a Gaussian impact-parameter dependent profile, are used to estimate the underlined theoretical uncertainties of our calculations. The results for the proton target and with charmonium in the final state are in agreement with the available HERA data, while in the case of nucleus target we make predictions for $gamma A$ and $AA$ differential cross sections at different $W$ and at $sqrt{s}=5.02$ TeV, respectively.
