arXiv subjects
Publications and source records attributed to Wolfgang Ochs.
The angular correlation function of partons in a jet, as derived from perturbative QCD, is nonanalytic at a critical angle which separates a multiparticle regime with scaling properties from a regime with few particles near the hadronisation scale. Some phenomenological consequences are discussed.
Angular correlations of partons have been derived for high energy jets in QCD. Interesting new scaling properties with two redundant variables (jet energy $P$ and jet opening angle $Θ$) emerge which can be tested within a parton-hadron duality picture. Recent results from LEP support the scaling in $Θ$; the scaling in both $P$ and $Θ$ could be tested with jets from deep inelastic scattering or with high $p_T$ jets.
The spectra of charged particles in the energy variable $ξ= \log 1/x$ (``the hump backed plateau'') are analyzed in terms of moments in order to investigate the sensitivity to the running of $α_s$ in particular towards small scales, and to further test thereby the local parton hadron duality picture. The modified leading log approximation (MLLA) of QCD provides a very satisfying description of the $e^+e^-$ data in the full range of c.m. energies from about 1 up to 91 GeV. The same calculation but with fixed coupling $α_s$ yields moments which are inconsistent with the data already close to threshold. In particular the soft particles ($E\le 1$~GeV) reflect directly the running of $α_s$.
Predictions for angular correlations between an arbitrary number of partons are derived in the high energy limit. The quantities considered depend on angles and primary energy through a single variable $ε$ which implies certain scaling properties and relations between quite different observables. These asymptotic predictions derived in the double log approximation of QCD are checked against Monte Carlo calculations at the parton and hadron level.
We derive the angular correlation functions between an arbitary number of partons inside a quark or gluon jet emerging from a high energy hard collision. As an application results for the correlation in the relative angle between two partons as well as the multiplicity moments of any order for partons in a sidewise angular region are calculated. At asymptotic energies the distributions of rescaled angular variables approach a scaling limit of a new type with two redundant quantities. All observables reveal the power behaviour characteristic to the fully developed selfsimilar cascade in appropriate regions of phase space. We present analytical results from the double logarithmic approximation as well as Monte Carlo results.