Hagiwara, Kaoru
**
Kou, E.
[UCL]
**
Lin, Z.H.
Qiao, C.F.
Zhu, G.H.
**(eng)**
Inclusive $J/\psi$ productions in $e^+ e^-$ annihilation is studied in the
framework of NRQCD. We first review the leading-order calculations of the cross
sections for $e^+ e^- \to J/\psi c \bar{c}$ and $e^+ e^- \to J/\psi g g$ and
find that their ratio is about 1:1.5 at $\sqrt{s}\simeq 10$\gev. This result is
in conflict with the current measurements by the Belle Collaboration, which
finds that the process $e^+e^- \to J/\psi c\bar{c}$ accounts for about 2/3 of
all the prompt $J/\psi$'s. We show that the discrepancy in the total rate as
well as in the $J/\psi$ momentum distributions can be resolved by considering a
large renormalization $K$ factor ($K\simeq 4$) for the $J/\psi c \bar {c}$
cross section and by taking into account collinear suppression in the end-point
energy region of $J/\psi g g$ production. Detailed studies of the model
predictions in terms of the density matrix are performed and various momentum
and angular distributions are presented as functions of the $K$ factors. These
distributions can be used to determine the normalizations of each subprocess
provided that the production and decay angular distributions do not alter much
by higher order corrections.
Comment: 25 pages with 8 figures

Bibliographic reference |
Hagiwara, Kaoru ; Kou, E. ; Lin, Z.H. ; Qiao, C.F. ; Zhu, G.H.. *Inclusive J / psi productions at e+ e- colliders.* In: *arXiv*, |

Permanent URL |
http://hdl.handle.net/2078/30909 |