## Abstract

We derive expressions for the differential distributions and the total cross section of the double-parton interaction in direct photon interaction with proton and nuclei. We demonstrate that in this case the cross section is more directly related to the nucleon generalized parton distribution than in the case of double-parton interactions in the proton–proton collisions. We focus on the production of two dijets each containing charm (anticharm) quarks and carrying (Formula Presented.) (Formula Presented.) fractions of the photon momentum. Numerical results are presented for the (Formula Presented.) (Formula Presented.) collisions at LHeC, HERA, and for the ultraperipheral (Formula Presented.) (Formula Presented.) collisions at the LHC. We find that the events of this kind would be abundantly produced at the LHeC. For (Formula Presented.) (Formula Presented.) TeV the expected rate is (Formula Presented.) (Formula Presented.) events for 1 year ((Formula Presented.) (Formula Presented.) s) of running and the luminosity (Formula Presented.) (Formula Presented.) cm (Formula Presented.) (Formula Presented.), for the transverse cutoff of (Formula Presented.) (Formula Presented.) GeV. This would make it feasible to use these processes for the model independent determination of two parton GPDs in nucleon and in nuclei. We also find that a significant number of such double-parton interactions should be produced in (Formula Presented.) (Formula Presented.) (Formula Presented.) and (Formula Presented.) (Formula Presented.) (Formula Presented.) collisions at the LHC: (Formula Presented.) (Formula Presented.) for (Formula Presented.) (Formula Presented.)–(Formula Presented.) (Formula Presented.), and (Formula Presented.) (Formula Presented.) for (Formula Presented.) (Formula Presented.)–(Formula Presented.) (Formula Presented.) collisions for the same transverse momentum cutoff and running time (Formula Presented.) (Formula Presented.), and in HERA where (Formula Presented.) (Formula Presented.) events were produced for the integrated HERA luminosity of 1.2 fb (Formula Presented.) (Formula Presented.). Further studies are necessary to identify the kinematics where these MPIs could be separated from conventional 2-to-4 multijet events.

Original language | English (US) |
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Article number | 3214 |

Journal | European Physical Journal C |

Volume | 74 |

Issue number | 12 |

DOIs | |

State | Published - Dec 4 2014 |

## All Science Journal Classification (ASJC) codes

- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)