Authors 
: 

Document type 
: 
Preprint 
Abstract 
: 
[eng] Inclusive $J/\psi$ productions in $e^+ e^$ annihilation is studied in the
framework of NRQCD. We first review the leadingorder 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 endpoint
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 
Access type 
: 
Accès libre

Publication date 
: 
2004 
Affiliation 
: 
UCL 
Keywords 
: 
High Energy Physics  Phenomenology 
Links 
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