Spin alignment in heavy and light flavour systems at OPAL

Authors
Citation
S. Robins, Spin alignment in heavy and light flavour systems at OPAL, NUCL PH B-P, 75B, 1999, pp. 231-235
Citations number
19
Categorie Soggetti
Physics
Journal title
NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS
ISSN journal
09205632 → ACNP
Volume
75B
Year of publication
1999
Pages
231 - 235
Database
ISI
SICI code
0920-5632(199904)75B:<231:SAIHAL>2.0.ZU;2-P
Abstract
Spin alignment of inclusive vector mesons and longitudinal polarization of Lambda hyperons have been measured in a sample of 4.3 million hadronic Z(0) decays from the OPAL detector at LEP. Leading, light vector mesons have be en found to populate preferentially the helicity-zero state, a result which has no firm theoretical explanation. The values of off-diagonal elements o f the helicity density matrix are in agreement with a theory based on the S tandard Model with coherent fragmentation. The longitudinal polarization of the Lambda is well described by a model in which the constituent strange q uark carries all of the hyperon spin.