New mechanisms for double charmed meson production at the LHCb

We discuss production of D-0 D-0 (and D D) pairs related to the LHCb Collaboration results for root s = 7 TeV in proton -proton scattering. We consider double-parton scattering (DPS) mechanisms of double c (c) over bar production and subsequent cc-* D-0 D-0 hadronization as well as double g and mixed gcc production with gg -> D-0 D-0 and gc -> D D hadronization calculated with the help of the scale-dependent hadronization functions of Kniehl et al. Single-parton scattering (SPS) mechanism of digluon production is also taken into account. We compare our results with several correlation observables in azimuthal angle phi D-0 D-0 between D mesons or in dimeson invariant mass MDODO. The inclusion of new mechanisms with g -> D fragmentation leads to larger cross sections, than when including only DPS mechanism cc > D-0 D-0 with standard scale -independent fragmentation functions. Some consequences of the presence of the new mechanisms are discussed. In particular a larger (ref/ is needed to describe the LHCb data. There is a signature that sigma(eff) may depend on transverse momentum of c quarks and/or c antiquarks. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:creative.rog/licenses/by/4.0). Funded by SCOAP(3).