Speakers
Antoni Szczurek
(Institute of Nuclear Physics)
Rafal Maciula
(Institute of Nuclear Physics PAN)
Description
We compare results of exact calculations of single-parton scattering (SPS)
and double-parton scattering (DPS) for production of
$c \bar c c \bar c$ and for $D-D$ meson correlations [1]. Each step of DPS is
calculated within $k_t$-factorization approach, i.e. effectively including next-to-leading order corrections.
The SPS calculations are performed in collinear approximation
with exact matrix element for $g g \to c \bar c c \bar c$ subprocess.
The new results are compared with results of previous calculation
with approximate matrix elements in high-energy approximation.
The cross section for the exact calculation is bigger only at small
invariant masses and small rapidity difference between
two $c$ quarks (or two $\bar c$ antiquarks).
We compare correlations in rapidities of two $c$ (or two $\bar c$) for
DPS and SPS contributions.
Finally we compare our predictions for $DD$ meson pairs with recent results of
the LHCb collaboration for invariant mass, rapidity distance between
mesons and dimeson invariant mass. The predicted shapes are similar
to the measured ones, however, some strength seems to be lacking.
Possible missing contribution within the framework of DPS mechanism is suggested.
Our new calulations clearly confirm the dominance of DPS in the
production of events with double charm.
[1] A. van Hameren, R. Maciula and A. Szczurek, arXiv:1402.6972 [hep-ph].
Primary authors
Antoni Szczurek
(Institute of Nuclear Physics)
Rafal Maciula
(Institute of Nuclear Physics PAN)
