DOI 10.1007/s100529800716
Higher Fock states and power counting in exclusive P-wave quarkonium decays
Jan Bolz1 - Peter Kroll1 - Gerhard A. Schuler2
1 Fachbereich Physik, Universität Wuppertal,
D-42097 Wuppertal, Germany (e-mail:
kroll@theorie.physik.uni-wuppertal.de)
2 Theory Division, CERN,
CH-1211 Geneva 23, Switzerland
(e-mail: Gerhard.Schuler@cern.ch)
Received: 25 April 1997 / Published online: 20 February 1998
Abstract
Exclusive processes at large momentum transfer Q factor into
perturbatively calculable short-distance parts and long-distance
hadronic wave functions. Usually, only contributions from the leading
Fock states have to be included to leading order in 1/Q. We show that
for exclusive decays of P-wave quarkonia the contribution from
the next-higher Fock state contributes at the same
order in 1/Q. We investigate how the constituent gluon attaches to the hard
process in order to form colour-singlet final-state hadrons and argue that
a single additional long-distance factor is sufficient to parametrize the
size of its contribution. Incorporating transverse degrees of freedom and
Sudakov factors, our results are perturbatively stable in the sense that
soft phase-space contributions are largely suppressed.
Explicit calculations yield good agreement with data on
decays into pairs of pions, kaons, and etas. We also comment on
decays into two pions.
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