Speaker
Prof.
Antoni Szczurek
(Cracow, INP & Rzeszow Univ.)
Description
We discuss charm production at LHC. The production of single $c \bar c$ pairs
is calculated in the $k_t$-factorization approach. We use several
unintegrated gluon distributions from the literature. Some of them
include effect of small-$x$ saturation and fulfill Balitsky-Kovchegov
evolution equation. The hadronization is included with the help of
fragmentation functions found for the production of $c$ ($\bar
c$) in $e^+ e^-$ collisions. Differential distributions for several
charmed mesons will be presented and compared to recent results of the ALICE
and LHCb collaborations. Some missing strength is identified.
Different schemes of fragmentation are discussed.
Furthermore we discuss production of two pairs of $c \bar c$ within a simple
formalism of double-parton scattering (DPS). Surprisingly large
cross sections, comparable to single-parton scattering (SPS)
contribution, are predicted for LHC energies.
Both total inclusive cross section as a function of energy and
differential distributions are shown.
We include recently discussed evolution of double partons in the case
of two scales.
We discuss perspectives how to identify the double scattering
contribution. We find much larger cross section for large rapidity distance
between charm quarks from different hard parton scatterings
compared to single scattering.
First predictions for two $c \bar c$ pair production in single-parton
scattering will be presented.
Predictions for the production of different pairs of charm mesons
($D0 $D0$, D0 {\bar D}0$, etc.) are presented for the kinematics of
LHCb experiment.
I will show also predictions for so-called nonphotonic electrons and muons
coming from the semileptonic decays of charmed mesons.
The double-parton scattering gives large contribution with large
(pseudo)rapidity gap between electrons ($e^+ e^+, $e^- e^-, $e^+ e^-$)
or muons. This can be measured experimentally.
Author
Prof.
Antoni Szczurek
(Cracow, INP & Rzeszow Univ.)
