5 research outputs found
Search for promptly produced heavy quarkonium states in hadronic Z decays
A search has been made for direct production of heavy quarkonium states
in more than 3 million hadronic Z(0) decays in the 1991-1994 DELPHI
data, Prompt J/psi, psi(2S) and Upsilon candidates have been searched
for through their leptonic decay modes using criteria based on the
kinematics and decay vertex positions. New upper limits are set at the
90% confidence level for Br(Z(0) –> (Q (Q) over bar) X)/Br(Z(0) –>
hadrons) for various strong production mechanisms of J/psi and Upsilon;
these range down to 0.9 x 10(-4). The limits are set in the presence of
a small excess (similar to 1% statistical probability of a background
fluctuation) in the sum of candidates from prompt J/psi, psi(2S),
Upsilon(1S), Upsilon(2S) and Upsilon(3S) relative to the estimated
background