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.
Copyright Springer-Verlag
