Production of $c \bar c c \bar c$ in double-parton scattering within $k_{t}$-factorization approach -- meson-meson correlations

TL;DR

This paper investigates the production of double charm quark pairs in proton-proton collisions at the LHC, emphasizing the role of double-parton scattering within a $k_t$-factorization framework and its impact on meson-meson correlations.

Contribution

It introduces a detailed $k_t$-factorization approach to calculate DPS contributions to double charm production, including meson correlations and differential distributions, with comparisons to experimental data.

Findings

DPS cross section aligns with LHCb measurements within uncertainties.

KMR gluon distribution best reproduces higher-order effects.

SPS contribution is relatively small compared to DPS.

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, i.e. effectively including next-to-leading order corrections. The conditions how to identify the DPS contribution are presented. The discussed mechanism unavoidably leads to the production of pairs of mesons: $D_i D_j$ (each containing $c$ quarks) or $\bar D_i \bar D_j$ (each containing $\bar c$ antiquarks). We calculate corresponding production rates for different combinations of charmed mesons as well as some differential distribution 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, which very well simulates higher-order corrections. 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.