https://doi.org/10.1140/epjc/s10052-016-4551-5
Regular Article - Theoretical Physics
Open charm production in double parton scattering processes in the forward kinematics
1
Department of Physics, Technion – Israel Institute of Technology, Haifa, Israel
2
Physics Department, Pennsylvania State University, University Park, PA, USA
* e-mail: blok@physics.technion.ac.il
Received:
2
August
2016
Accepted:
28
November
2016
Published online:
18
December
2016
We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment. We find that the mean field approximation for the double parton GPD (generalized parton distributions), which neglects parton–parton correlations, underestimates the rate by a factor of 2. The enhancement due to the perturbative QCD correlation 
mechanism which explains the rate of double parton interactions at the central rapidities is found to explain 60 
80% of the discrepancy. We argue that the nonperturbative fluctuations leading to non-factorized (correlated) contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, the two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the 
(i.e. the ratio of double and square of single inclusive rates) in the discussed kinematics as a function of 
. The account for two correlation mechanisms strongly reduces the sensitivity of the results to the starting point of the QCD evolution.
© The Author(s), 2016
