Rafal Maciula

Open charm production at the LHC -

We discuss inclusive production of open charm in proton-proton scattering at LHC. The calculation is performed within the kt-factorization approach. Different models of unintegrated gluon distributions (UGDF) from the literature are used. The theoretical transverse momentum as well as (pseudo)rapidity distributions of charmed mesons are compared with recent experimental data of ATLAS, ALICE and LHCb collaborations. Only the calculation with Kimber-Martin-Ryskin (KMR) UGDF gives results comparable to experimental ones. All other popular models of UGDF significantly underpredict experimental data. Several sources of uncertainties of the theoretical predictions are also studied in details. In addition we discuss correlations between D and � D mesons. Good description of experimental distribution in invariant mass and in relative azimuthal angle between D and � D mesons is achieved for the KMR UGDF. The considered correlation observables measured by the LHCb experiment were not discussed in other approaches in the literature.

k_{t}

The double parton distributions (dPDF), both conventional and those corresponding to parton splitting, are calculated and compared for different two-parton combinations. The conventional and splitting dPDFs have very similar shape in

-factorization approach

x_1

Conventional versus single-ladder-splitting contributions to double parton scattering production of two quarkonia, two Higgs bosons and c anti cc anti c

and

Production of twocc¯pairs in double-parton scattering

x_2

Production of

. We make a first quantitative evaluation of the single-ladder-splitting contribution to double parton scattering (DPS) production of two S- or P-wave quarkonia, two Higgs bosons and

c \bar c c \bar c

c \bar c c \bar c

in double-parton scattering within

. The ratio of the single-ladder-splitting to conventional contributions is discussed as a function of centre-of-mass energy, mass of the produced system and other kinematical variables. Using a simple model for the dependence of the conventional two-parton distribution on transverse parton separation (Gaussian and independent of

k_{t}

x_i

-factorization approach -- meson-meson correlations

and scales), we find that the 2v1 contribution is as big as the 2v2 contribution discussed in recent years in the literature. This means that the phenomenological analyses of