3 research outputs found
Reexamining radiative decays of quarkonium into and
Recently CLEO has studied the radiative decay of into and
an upper limit for the decay has been determined. Confronting with this upper
limit,most of theoretical predictions for the decay fails. After briefly
reviewing these predictions we re-examine the decay by separating
nonperturbative effect related to the quarkonium and that related to or
, in which the later is parameterized by distribution amplitudes of
gluons in . With this factorization approach we obtain theoretical
predictions which are in agreement with experiment. Uncertainties in our
predictions are discussed. The possibly largest uncertainties are from
relativistic corrections for and the value of the charm quark mass. We
argue that the effect of these uncertainties can be reduced by using quarkonium
masses instead of using quark masses. An example of the reduction is shown with
an attempt to explain the violation of the famous 14% rule in radiative decays
of charmonia.Comment: 9 Pages, Latex fil
Further Experimental Studies of Two-Body Radiative \Upsilon Decays
Continuing our studies of radiative Upsilon(1S) decays, we report on a search
for Upsilon to gamma eta and Upsilon to gamma f_{J}(2220) in 61.3 pb^{-1} of
e^{+}e^{-} data taken with the CLEO II detector at the Cornell Electron Storage
Ring. For the gamma eta search the three decays of the eta meson to
pi^{+}pi^{-}pi^{0}, pi^{0}pi^{0}pi^{0}, and gamma gamma were investigated. We
found no candidate events in the two (3\pi)^{0} modes and no significant excess
over expected backgrounds in the gamma gamma mode to set a limit on the
branching fraction of B(Upsilon to gamma eta) < 2.1 x 10^{-5} at 90% C.L. The
three charged two-body final states h h-bar (h = pi^{+}, K^{+}, p) were
investigated for f_{J}(2220) production, with one, one, and two events found,
respectively. Limits at 90% C.L. of B(\Upsilon to gamma f_{J}) x B(f_{J} to h
h-bar) ~ 1.5 x 10^{-5} have been set for each of these modes. We compare our
results to measurements of other radiative Upsilon decays, to measurements of
radiative J/psi decays, and to theoretical predictions.Comment: 19 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to Physical Review