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ID: 544299.0, MPI für Physik / MPI für Physik
QCD coherence and correlations of particles with restricted momenta in hadronic Z decays
Authors:The OPAL collaboration; Abbiendi, G.; et al.
Date of Publication (YYYY-MM-DD):2006
Title of Journal:Physics Letters B
Journal Abbrev.:Phys.Lett.B
Issue / Number:638
Start Page:30
End Page:38
Audience:Not Specified
Intended Educational Use:No
Abstract / Description:QCD coherence effects are studied based on measurements of correlations of particles with either restricted transverse momenta, pT<pTcut, where pT is defined with respect to the thrust axis, or restricted absolute momenta, p equiv |p| < pcut, using about four million hadronic Z decays recorded at LEP with the OPAL detector. The correlations are analyzed in terms of normalized factorial and cumulant moments. The analysis is inspired by analytical QCD calculations which, in conjunction with Local Parton-Hadron Duality (LPHD), predict that, due to colour coherence, the multiplicity distribution of particles with restricted transverse momenta should become Poissonian as pTcut decreases. The expected correlation pattern is indeed observed down to pTcut approx 1GeV but not at lower transverse momenta. Furthermore, for pcut to 0 GeV a strong rise is observed in the data, in disagreement with theoretical expectation. The Monte Carlo models reproduce well the measurements at large pTcut and pcut but underestimate their magnitudes at the lowest momenta. The e+e- data are also compared to the measurements in deep-inelastic e+p collisions. Our study indicates difficulties with the LPHD hypothesis when applied to many-particle inclusive observables of soft hadrons.
Classification / Thesaurus:OPAL
Comment of the Author/Creator:17 pages, 4 figures, Submitted to Phys. Letts. B
External Publication Status:published
Document Type:Article
Communicated by:N.N.
Affiliations:MPI für Physik
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