H. C. Eggers

Analysis of multiplicity moments for hadronic multiparticle data

Abstract We show that rapidity-bin factorial moments contain a large combinatoric contribution from two-particle correlations. In addition, the higher-order correlations are nonnegligible and increase with energy. The analysis is completely general and also applies for the case where the moments scale. We find that the linked-pair approximation (LPA) for higher correlations is valid for UA1 and UA5 data, with coefficients that are approximately independent of energy and somewhat smaller than for the negative binomial distribution.

The Correlation integral as probe of multiparticle correlations

Abstract We report on a considerable improvement of the usual factorial moment method used in the study of correlations and in particular of intermittency: by means of integrals of the correlation functions over a strip domain, we obtain greater stability and smaller statistical errors. The benefit of using correlation integrals rises with increasing order of the moment and with increasing dimension of the variables. An algorithm for the actual computation of the so-called strip integrals directly from experimental data is explained in detail. Illustrations of the power of the correlation integral method are given in terms of the NA22 spike event, a two-dimensional JETSET calculation and the p -model.

Stochastic energy-cascade model for (1 + 1)-dimensional fully developed turbulence

Geometrical random multiplicative cascade processes are often used to model positive-valued multifractal fields such as the energy dissipation in fully developed turbulence. We propose a dynamical generalization describing the energy dissipation in terms of a continuous and homogeneous stochastic field in one space and one time dimension. In the model, correlations originate in the overlap of the respective spacetime histories of field amplitudes. The theoretical two- and three-point correlation functions are found to be in excellent agreement with their equal-time counterparts extracted from wind tunnel turbulent shear flow data.

STRANGENESS AND QUARK GLUON PLASMA: ASPECTS OF THEORY AND EXPERIMENT

A survey of our current understanding of the strange particle signature of quark gluon plasma is presented. Emphasis is placed on the theory of strangeness production in the plasma and recent pertinent experimental results. Useful results on spectra of thermal particles are given.

CORRELATIONS AND INTERMITTENCY IN HIGH ENERGY MULTIHADRON DISTRIBUTIONS

The linked-pair approximation to the hierarchy of cumulant correlation functions is tested in the central rapidity domain, where approximate translation invariance is appropriate. The bin-averaged factorial moments up to the fifth order are well described in terms of the second-order experimental moment for final states created in hadronic collisions. Given the two-particle correlation function, the only constants appearing in the higher moments are very close to those-appropriate to the negative binomial distribution, as pointed out recently by De Wolf. The close correspondence of the linked-pair decomposition to the same structure occurring in galaxy correlations (with slightly different coefficients) is noted, as is the apparently negative binomial character of the number distribution of galaxies in clusters. Preliminary results are discussed for the rapidity distributions arising in proton-nucleus and nucleus-nucleus collisions. We present a variety of fits to correlation functions and also discuss bin-bin correlations deriving from our model.

Higher order pion interferometry: Moments and cumulants

Abstract Pion interferometry can be viewed as intermittency analysis in terms of momentum transfer of like-sign particles. By putting the common practice of event mixing on a sound footing and extending its use, we provide the tools to eliminate the combinatoric background contained in the usual correlation functions. Information on true higher order correlations can now be extracted and the question whether these play any role in interferometry addressed experimentally.

Multiplicity dependence of correlation functions in p̄p reactions at √s=630 GeV

Abstract Discussions about Bose–Einstein correlations between decay products of coproduced W-bosons again raise the question about the behaviour of correlations if several strings are produced. This is studied by the multiplicity dependence of correlation functions of particle pairs with like-sign and opposite-sign charge in p p reactions at s =630 GeV.

HBT shape analysis with q-cumulants

Taking up and extending earlier suggestions, we show how two- and three-dimensional shapes of second-order HBT correlations can be described in a multivariate Edgeworth expansion around Gaussian ellipsoids, with expansion coefficients, identified as the cumulants of pair momentum difference q , acting as shape parameters. Off-diagonal terms dominate both the character and magnitude of shapes. Cumulants can be measured directly and so the shape analysis has no need for fitting.

Generalized moments and cumulants for samples of fixed multiplicity

Factorial moments and cumulants are usually defined with respect to the unconditioned Poisson process. Conditioning a sample by selecting events of a given overall multiplicity {ital N} necessarily introduces correlations. By means of Edgeworth expansions, we derive generalized cumulants which define correlations with respect to an arbitrary process rather than just the Poisson case. The results are applied to correlation measurements at fixed {ital N}, to redefining short-range versus long-range correlations and to normalization issues. {copyright} {ital 1996 The American Physical Society.}

QUANTITATIVE CHARACTERISATION OF CORRELATION FUNCTION SHAPES WITH A MULTIVARIATE EDGEWORTH EXPANSION

Second-order HBT correlation functions can be expanded in terms of correlated gaussian ellipsoids and their derivatives. The resulting multidimensional Edgeworth expansion in terms of cumulants and hermite tensors contains 15 fourth-order and 28 sixth-order cumulants which act as shape parameters. Off-diagonal terms dominate both the character and magnitude of shape changes. We show how cumulants can be measured directly and so the procedure has no need for fitting.