25 research outputs found
Intermittency and Correlations at LEP and at HERA
A review on recent investigations of local fluctuations and genuine
correlations in electron-positron annihilations at LEP and in positron-proton
collisions at HERA is given.Comment: Invited talk given at the XXXth Int. Symposium on Multiparticle
Dynamics (ISMD 2000), 9-15 October 2000, Tihany, Lake Balaton, Hungar
Multiplicities and particle production at LEP
Recent results on hadron multiplicities in heavy and light quark
fragmentation above the Z peak (OPAL), and multiplicity distribution analysis
(L3) and inclusive f_1 production (DELPHI) in hadronic Z decays are presented.Comment: 3 pages, 4 figs. Talk given at the International Europhysics
Conference on High Energy Physics, EPS-HEP2003, 17-23 July 2003, Aachen,
German
Multiplicities and Correlations at LEP
A brief review on recent charge multiplicity and correlation measurements at
LEP is given. The measurements of unbiased gluon jet multiplicity are
discussed. Recent results on charged particle Bose-Einstein and Fermi-Dirac
correlations at LEP1 are reported. New results on two-particle correlations of
neutral pions are given. Correlations of more than two particles (high-order
correlations) obtained using different methods are performed. Recent
Bose-Einstein correlation measurements at LEP2 are discussed.Comment: 5 pages. Invited talk presented at the Xth International Workshop on
Deep Inelastic Scattering (DIS2002), Cracow, 30 April - 4 May 200
Relating multihadron production in hadronic and nuclear collisions
The energy-dependence of charged particle mean multiplicity and
pseudorapidity density at midrapidity measured in nucleus-nucleus and
(anti)proton-proton collisions are studied in the entire available energy
range. The study is performed using a model, which considers the multiparticle
production process according to the dissipating energy of the participants and
their types, namely a combination of the constituent quark picture together
with Landau relativistic hydrodynamics. The model reveals interrelations
between the variables under study measured in nucleus-nucleus and
nucleon-nucleon collisions. Measurements in nuclear reactions are shown to be
well reproduced by the measurements in (anti)proton-proton interactions common
and the corresponding fits are presented. Different observations in other types
of collisions are discussed in the framework of the proposed model. Predictions
are made for measurements at the forthcoming LHC energies.Comment: Europ. Phys. J. C (to appear). Recently CMS reported
(arXiv:1005.3299) on the midrapidity density value of 5.78 +/- 0.01(stat) +/-
0.23(syst) in pp collisons at 7 TeV, which agrees well with the value of 5.8
of our prediction
Effective-energy budget in multiparticle production in nuclear collisions
The dependencies of charged particle pseudorapidity density and transverse
energy pseudorapidity density at midrapidity on the collision energy and on the
number of nucleon participants, or centrality, measured in nucleus-nucleus
collisions are studied in the energy range spanning a few GeV to a few TeV per
nucleon. The model in which the multiparticle production is driven by the
dissipating effective energy of participants is introduced. The model is based
on the earlier proposed approach, combining the constituent quark picture
together with Landau relativistic hydrodynamics shown to interrelate the
measurements from different types of collisions. Within this model, the
dependence on the number of participants in heavy-ion collisions are found to
be well described in terms of the effective energy defined as a
centrality-dependent fraction of the collision energy. For both variables under
study, the effective energy approach reveals a similarity in the energy
dependence obtained for the most central collisions and centrality data in the
entire available energy range. Predictions are made for the investigated
dependencies for the forthcoming higher energy measurements in heavy-ion
collisions at the LHC.Comment: Regular article, Replaced with published versio
Probing Lorentz Violation in Neutrino Propagation from a Core-Collapse Supernova
Supernova explosions provide the most sensitive probes of neutrino
propagation, such as the possibility that neutrino velocities might be affected
by the foamy structure of space-time thought to be generated by
quantum-gravitational (QG) effects. Recent two-dimensional simulations of the
neutrino emissions from core-collapse supernovae suggest that they might
exhibit variations in time on the scale of a few milliseconds. We analyze
simulations of such neutrino emissions using a wavelet technique, and consider
the limits that might be set on a linear or quadratic violation of Lorentz
invariance in the group velocities of neutrinos of different energies, v/c = [1
\pm (E/M_{nuLV1})] or [1 \pm (E/M_{\nuLV2})^2], if variations on such short
time scales were to be observed, where the mass scales M_{nuLVi} might appear
in models of quantum gravity. We find prospective sensitivities to M_{nuLV1} ~
2 X 10^{13} GeV and M_{nuLV2} ~ 10^6 GeV at the 95% confidence level, up to two
orders of magnitude beyond estimates made using previous one-dimensional
simulations of core-collapse supernovae. We also analyze the prospective
sensitivities to scenarios in which the propagation times of neutrinos of fixed
energies are subject to stochastic fluctuations.Comment: 29 pages, 9 figures. A subsection added. The version to appear in
Phys. Rev.