Speaker
Dr
Seyed Mohammad Moosavi Nejad
(Yazd University)
Description
Fragmentation is the dominant production mechanism for heavy-quark-antiquark bound
states with large transverse momentum. We analytically calculate the initial scale
fragmentation functions (FFs) for a gluon and a heavy quark to split into $S$-wave heavy quarkonium states using the perturbative QCD.
Our analytical expression of FFs depends on the transverse momentum $k_T$ of the partons, and
contains most of the kinematical and dynamical properties of the process.
The analyses of this paper differ in that we present, for the first time, an analytical form of the
transverse momentum dependent FFs, using a different model (Suzuki's model) in comparison with the numerical results presented in other references
where the Braaten's model have been used.
These $k_T$ dependent FFs are necessary to calculate the differential cross sections $d\sigma/dk_T$, for which there are experimental data.
We also incorporate, for the first time, hadron mass effects in our calculations to improve the FFs at the small $z$ regions, where
$z$ is the fragmentation parameter.
These effects modify the relations between
partonic and hadronic variables and reduce the available phase space and are responsible for the low-z threshold.
Author
Dr
Seyed Mohammad Moosavi Nejad
(Yazd University)
