PN423 3 March 2000 Z Boson Pair Production in e

A study of Z boson pair production in e e - annihilation at center-of-mass energies above 190 GeV using the OPAL detector at LEP is reported. Final states containing only leptons, (# # - and # - ##), quark and lepton pairs, (qq# # - , qq##) and only quarks (qqqq) have been studied. In all states with at least one Z boson decaying hadronically, qq and bb final states are considered separately using lifetime and event-shape tags, thereby improving the cross-section measurement. The Z-pair cross-section measurements are which are consistent with the Standard Model prediction. Limits on anomalous ZZ# and ZZZ couplings are derived

INTERMITTENCY in

: Density fluctuations are studied in rapidity, separately for low and intermediate transverse momentum particles. In our data, the effect of intermittency is increased when the analysis is restricted to low p T particles. 1 EC Guest Scientist 2 Now at MPI, Munich, Germany 3 Bevoegdverklaard Navorser NFWO, Belgium 4 Partially supported by grants from CPBP 01.06 and 01.09. 5 Now at Syracuse Univ., Syracuse, NY, USA Density fluctuations in multiparticle production have recently gained considerable attention. To study these fluctuations in detail, Bia/las and Peschanski [1] have suggested to analyze scaled factorial moments of the multiplicity distribution in smaller and smaller phase-space bins, down to the experimental resolution. Including the case of a non-constant overall rapidity distribution, these moments can be defined as a double average starting "vertically" (over events): hF i i v = 1 M X m 1 Nevt P evt F i;m hn m i i : (1) Here, M is the number of phase-..

Higher order Bose-Einstein correlations in

: Bose-Einstein correlations up to fourth order are presented at p s = 22 GeV. Genuine third-order correlations are observed. The experimental data are compared with predictions from a quantum statistical approach of radiation from a partially coherent source and with the FRITIOF model. 1 EC guest scientist, now at DESY, Hamburg 2 KUN Fellow from the Jagellonian University, Krakow 3 Onderzoeksleider NFWO, Belgium 4 Supported by the Polish State Committee for Scientific Research 5 Now at UIA, Wilrijk, Belgium 1 Introduction and formalism The dynamical properties of complex systems can be described by two-, three- and moreparticle correlation functions. In statistical physics, e.g. in the theory of gases, multiparticle correlations are the result of interactions between pairs, triplets, etc. of molecules [1]. In high energy strong interaction physics, the correlation characteristics of multihadron production reflect the complex (and not yet established) dynamical properties..

Tests of enhanced leading order QCD in W boson plus jets events from 1.8 TeV barp p collisions

We present a study of events with W bosons and hadronic jets produced in (p) over barp collisions at a center of mass energy of 1.8 TeV. The data consist of 51400 W-->e nu decay candidates from 108 pb(-1) of integrated luminosity collected using the CDF detector at the Fermilab Tevatron collider. Cross sections and jet production properties have been measured for W+greater than or equal to1 to greater than or equal to4 jet events. The data compare well to predictions of leading-order QCD matrix element calculations with added gluon radiation and simulated parton fragmentation