Production of two $c \bar c$ pairs in double-parton scattering within $k_t$-factorization

TL;DR

This paper investigates the production of two charm-anticharm pairs in proton-proton collisions at the LHC, highlighting the significance of double-parton scattering within the $k_t$-factorization framework and comparing it with single-parton scattering.

Contribution

It introduces a detailed $k_t$-factorization approach to calculate DPS contributions for double charm production and compares theoretical predictions with experimental data.

Findings

DPS contribution is comparable to experimental measurements.

$k_t$-factorization with KMR gluon distribution best fits data.

SPS contribution is relatively small in the analyzed processes.

Abstract

We discuss production of two pairs of $c \bar c$ in proton-proton collisions at the LHC. Both double-parton scattering (DPS) and single-parton scattering (SPS) contributions are included in the analysis. Each step of DPS is calculated within $k_t$-factorization approach. The conditions how to identify the DPS contribution are presented. The discussed mechanism leads to the production of pairs of mesons: each containing $c$ quarks or each containing $\bar c$ antiquarks. We discuss corresponding production rates and some differential distributions for $(D^0 D^0$ + $\bar D^0 \bar D^0)$ production. Within large theoretical uncertainties the predicted DPS cross section is fairly similar to the cross section measured recently by the LHCb collaboration. The best description is obtained with the Kimber-Martin-Ryskin (KMR) unintegrated gluon distribution. The contribution of SPS, calculated in the high-energy approximation, turned out to be rather small. Finally, we emphasize significant contribution of DPS mechanism to inclusive charmed meson spectra measured recently by ALICE, ATLAS and LHCb.