Speaker
Hee Sok Chung
(Argonne National Laboratory)
Description
We compute fragmentation corrections to hadroproduction of the
quarkonium states $J/\psi$, $\chi_{cJ}$, and $\psi(2S)$ at leading power
in $m_c^2/p_T^2$, where $m_c$ is the charm-quark mass and $p_T$ is the
quarkonium transverse momentum. The computation is carried out in the
framework of nonrelativistic QCD. We include corrections to the
parton-production cross sections through next-to-leading order in the
strong coupling $\alpha_s$ and corrections to the fragmentation
functions through second order in $\alpha_s$. We also sum leading
logarithms of $p_T^2/m_c^2$ to all orders in perturbation theory. We
find that, when we combined these leading-power fragmentation
corrections with fixed-order calculations through next-to-leading order
in $\alpha_s$, we are able to obtain good fits for $p_T\geq 10$ GeV to
hadroproduction cross sections that were measured at the Tevatron and
the LHC. Using values for the nonperturbative long-distance matrix
elements that we extract from the cross-section fits, we make
predictions for the polarizations of the quarkonium states. We obtain
good agreement with measurements of the polarizations, with the
exception of the CDF Run II measurement of the prompt $J/\psi$
polarization, for which the agreement is only fair. In the predictions
for the prompt-$J/\psi$ cross sections and polarizations, we take
into account feeddown from the $\chi_{cJ}$ and $\psi(2S)$ states.
Authors
Geoffrey Bodwin
(Argonne National Laboratory)
Hee Sok Chung
(Argonne National Laboratory)
Jungil Lee
(Korea University)
Kuang-Ta Chao
(Peking University)
U-Rae Kim
(Korea University)
Yan-Qing Ma
(Peking University)
