Double open charm meson production at the LHC: new single- and double-parton scattering mechanisms

Rafał Maciuła,Antoni Szczurek

doi:10.1051/epjconf/201613005013

Abstract

We discuss D 0 D 0 meson-meson pair production related to the recent LHCb experimental results obtained at √s = 7 TeV. We consider double-parton scattering (DPS) mechanisms of double cc production and subsequent standard cc → D 0 D 0 scale-independent hadronization as well as double g and mixed gcc production with gg → D 0 D 0 and gc → D 0 D 0 scale-dependent hadronization. The latter scenario with g → D 0 fragmentation components results in a new single-parton scattering (SPS) mechanism of digluon production which is also taken here into account. Results of the numerical calculations are compared with the LHCb data for correlation observables in azimuthal angle φ D 0 D 0 between D 0 mesons, in dimeson invariant mass M D 0 D 0 and in transverse momentum of the meson from the D 0 D 0 pair. The inclusion of the new mechanisms with g → D 0 fragmentation leads to a larger cross sections and to slightly different shapes of the calculated correlation observables.

Highlights

Some time ago we have predicted that at large energies, relevant for the Large Hadron Collider, production of double charm should be dominated by the double-parton scattering (DPS) mechanism [1]
In the step those predictions based on leading-order (LO) collinear approach were improved by application of the kt-factorization approach which effectively includes higher-order QCD effects [2, 3]
The single-parton scattering (SPS) contribution to the double cccross section was found to be rather small, much smaller than the DPS one, and cannot explain the total and differential cross sections measured by the LHCb

Summary

Introduction

Some time ago we have predicted that at large energies, relevant for the Large Hadron Collider, production of double charm should be dominated by the double-parton scattering (DPS) mechanism [1]. The extended studies provide a relatively good description of the LHCb experimental data [4] for both the total cross section and the dimeson correlation observables. Within these analyses the single-parton scattering (SPS) gg → cccccontribution was carefully discussed in both collinear [3] and kt-factorization [5] approaches. There, one can find a revisited comparison of the theoretical predictions based on the two hadronization scenarios for single D meson production, calculated with the same set of αS , scales, unPDFs and other details which are relevant for the discussion of double D meson production

Comparison to the LHCb data

Conclusions