Production of one and two $c \bar c$ pairs at LHC
  We report on charm production at LHC. The production of single $c \bar c$ pairs is calculated in the $k_t$-factorization approach with different unintegrated gluon distributions. Examples of transverse momentum distributions for charmed mesons are presented and compared to recent experimental results from LHC. Some missing strength is observed for most of UGDFs. Furthermore we discuss production of two $c \bar c$ pairs within double-parton scattering (DPS) and single-parton scattering (SPS) mechanisms. Surprisingly large cross sections, comparable to single $c \bar c$ pair production are predicted. We discuss first experimental results from LHCb collaboration on production of pairs of $D$ mesons of the same flavour. 
Antoni Szczurek and Rafal Maciula
hep-ph nucl-th