Study of hadronic decays of the
Z boson at LEP
By Alessandro de Angelis
In *Osaka 2000, High energy physics
Hadronization
Properties of b Quarks compared to Light Quarks in $q\bar{q}$ Events at
\sqrt{s} from 183 to 200 GeV
by P. Abreu, A. De Angelis and L.
Vitale (DELPHI Collaboration)
CERN-EP/2000-010, January 2000 (Published in Phys. Lett. B479 (2000) 118)
Abstract - During 1997, 1998 and 1999 the DELPHI detector at
LEP has collected data at centre-of-mass energies between 183 GeV and 200
GeV. We have used these data to measure the average charged particle multiplicity
in e+e- -> b-bbar events, n_bb, and the difference deltabl between n_bb
and the multiplicity, n_ll, in generic light quark (u,d,s) events. The
result is remarkably in agreement with QCD predictions, while it is inconsistent
with calculations assuming that the multiplicity accompanying the decay
of a heavy quark is independent of the mass of the quark itself.
Charged and
Identified Particles from the Hadronic Decay of W Bosons and in e+e- ->
qqbar from 183 to 200 GeV
by P. Abreu, G. Barbiellini, A.
De Angelis, N. Dos Anjos, D. Liko, N. Neufeld and L. Vitale (DELPHI Collaboration)
CERN-EP/Final, January 2000
(Published in Eur. Phys. J. C18 (2000) 203)
Abstract - Inclusive distributions of charged particles in W
decays are experimentally investigated using the statistics collected by
the DELPHI experiment at LEP during 1997, 1998 and 1999, at center-of-mass
energies from 183 to 200 GeV. The possible effects of interconnections
between the hadronic decays of two W are discussed.
Estimating
the Parameters of Bose-Einstein Correlations from the Two-Particle Correlation
Function in Multihadronic Final States
by A. De Angelis and L. Vitale
Nucl. Instr. Methods A423 (1999)
446.
Abstract - To estimate the strength of the Bose-Einstein correlations
and the radius of the hadronization region in multiparticle production,
the two-particle correlation functions R for identical pairs is adjusted
to a parametric function describing the enhancement at small momentum differences.
This is usually done by means of a binned uncorrelated least squares fit.
This article demonstrates that this procedure underestimates the statistical
errors. A recipe is given to construct from the data the covariance matrix
between the bins of the histogram of the two-particle correlation function.
The
Estimation of the Effective Centre of Mass Energy in q-qbar-gamma Events
from DELPHI
by P. Abreu, A. De Angelis,
G. Della Ricca, D. Fassouliotis, A. Grefrath, N. Kjaer, R. Henriques, M.
Mulders, M. Pimenta and L. Vitale
Nucl. Instr. Methods A427 (1999)
487.
Abstract - The photon radiation in the initial state lowers
the energy available for the e$^+$e$^-$ collisions; this effect is particularly
important at LEP2 energies (above the mass of the Z boson). Being aligned
to the beam direction, such initial state radiation is mostly undetected.
This article describes the procedure used by the DELPHI experiment at LEP
to estimate the effective centre-of-mass energy in hadronic events collected
at energies above the Z peak. Typical resolutions ranging from 2 to 3 GeV
on the effective center-of-mass energy are achieved, depending on the event
topology.
Interconnection
Effects in Multiparticle Production from WW Events at LEP
by A. De Angelis
Nucl. Phys. B (Proc. Suppl.) 71
(1999) 170.
Abstract - Interactions between the products of the hadronic
decays of different Ws in WW pair events can occur at several stages: from
the colour rearrangement between the quarks coming from the primary branching,
to the gluon exchange during the parton cascade, to the mixing of identical
pions due to Bose-Einstein correlations. Besides the intrinsic interest
of their study related to the understanding of the multiparticle production
mechanisms, these phenomena can affect the ultimate accuracy in the W mass
measurement by LEP 2. The status of the experimental analysis on interconnection
effects between W pairs hadronically decaying is reviewed in this paper.
Jet
and hadron production in ee annihilations
by A. De Angelis
Presented at Deep Inelastic Scattering
99, Berlin, April 1999; Nucl. Phys. B79 (1999) 475.
Abstract - The DELPHI detector at LEP is particularly suited
for hadron identification and for the identification of b-initiated jets.
This note presents recent results based on such characteristics.
Correlations Between
Particles from Different Ws in e+e- -> W^+W^- Events
by P. Abreu, A. De Angelis, Z. Metreveli,
R. Moller, N. Pukhaeva, N. van Remortel, K. Seth, S. Tabidze, A. Tomaradze,
F. Verbeure and L. Vitale (DELPHI Collaboration)
CERN DELPHI 99-159 CONF 330,
October 1999.
Abstract - The correlation functions R for like-sign and unlike-sign
particle pairs were measured for fully hadronic and for mixed decay WW
channels using the data collected by the DELPHI detector at LEP at center-of-mass
energy between 183 and 200 GeV. The correlation functions for particle
pairs in $q\bar{q}$ events at high energy were also measured.
Detecting
the Radiation Associated with the Creation of Charged Particles
by A. De Angelis
CERN DELPHI 98-34 PHYS 770,
April 1998.
Abstract - In high energy reactions, the creation of rapidly
moving charges is accompanied by a soft final state radiation. Experimental
measurements performed up to now give contradictory results. The study
of the radiation associated with the creation of charged particles in the
decay of Z bosons could clarify the situation. Such radiation could be
detectable in DELPHI.
Mail to alessandro.de.angelis@cern.ch