K. Ackerstaff et al., SPIN ALIGNMENT OF LEADING K-ASTERISK(892)DEGREES MESONS IN HADRONIC Z-DEGREES DECAYS, Physics letters. Section B, 412(1-2), 1997, pp. 210-224
Helicity density matrix elements for inclusive K(892)(0) mesons from
hadronic Z(0) decays have been measured over the full range of K(0) m
omentum using data taken with the OPAL experiment at LEP. A preference
for occupation of the helicity zero state is observed at all scaled m
omentum x(p) values above 0.3, with the matrix element rho(00) rising
to 0.66+/-0.11 for x(p)>0.7. The values of the real part of the off-di
agonal element rho(1-1) are negative at large x(p), with a weighted av
erage value of -0.09+/-0.03 for x(p)>0.3, in agreement with new theore
tical predictions based on Standard Model parameters and coherent frag
mentation of the q (q) over bar system from the Z(0) decay. All other
helicity density matrix elements measured are consistent with zero ove
r the entire x(p) range. The K(0) fragmentation function has also bee
n measured and the total rate determined to be 0.74+/-0.02+/-0.02 K(8
92)(0) mesons per hadronic Z(0) decay. (C) 1997 Published by Elsevier
Science B.V.