Speakers
Antoni Szczurek
(Institute of Nuclear Physics)
Rafal Maciula
(Institute of Nuclear Physics PAN)
Description
We present first results for the $2 \to 4$ single-parton scattering
$g g \to c \bar c c \bar c$ subprocess for the first time fully within
the $k_t$-factorization approach. In this calculation we have used
the Kimber-Martin-Ryskin unintegrated gluon distribution which effectively
includes some class of higher-order gluon emissions, and an off-shell
matrix element squared calculated using recently developed techniques.
The results are compared with our earlier result obtained within the
collinear approach.
Only slightly larger cross sections are obtained than in the case
of the collinear approach.
Inclusion of transverse momenta of gluons entering the hard process
leads to a much stronger azimuthal decorrelation between $c c$ and
$\bar c \bar c$ than in the collinear-factorization approach.
A comparison to predictions of double parton scattering (DPS) results
and the LHCb data strongly suggests that the assumption of two
fully independent DPS ($g g \to c \bar c \otimes g g \to c \bar c$)
may be too approximate.
1) A. van Hameren, R. Maciula and A. Szczurek,
"Single-parton scattering versus double-parton scattering
in the production of two $c \bar c$ pairs and charmed meson correlations
at the LHC",
Phys. Rev. D89 (2014) 094019.
2) A. van Hameren, R. Maciula and a. Szczurek,
Production of two charm quark-antiquark pairs
in single-parton scattering
within the $k_t$-factorization approach,
arXiv:1504.06491, submitted to Phys.Lett.B.
Author
Rafal Maciula
(Institute of Nuclear Physics PAN)
Co-authors
Andreas van Hameren
(IFJ PAN)
Antoni Szczurek
(Institute of Nuclear Physics)
