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.