Multiboson effects in multiparticle production

Abstract

The influence of multiboson effects on pion multiplicities, single-pion spectra and two-pion correlation functions is discussed in terms of an analytically solvable model. The applicability of its basic factorization assumption is clarified. An approximate scaling of the basic observables with the phase space density is demonstrated in the low density (gas) limit. This scaling and also its violation at high densities due to the condensate formation is described by approximate analytical formulae which allow, in principle, for the identification of the multiboson effects among others. For moderate densities indicated by the experimental data, a fast saturation of multiboson effects with the number of contributing cumulants is obtained, allowing for the account of these effects in realistic transport code simulations. At high densities, the spectra are mainly determined by the universal condensate term and the initially narrow Poisson multiplicity distribution approaches a wide Bose-Einstein one. As a result, the intercepts of the inclusive and fixed-$n$ correlation functions (properly normalized to 1 at large relative momenta) approach 2 and 1, respectively and their widths logarithmically increase with the increasing phase space density. It is shown that the neglect of energy-momentum constraints in the model is justified except near a multipion threshold, where these constraints practically exclude the possibility of a very cold condensate production. It is argued that spectacular multiboson effects are likely to be observed only in the rare events containing sufficiently high density (speckle) fluctuations.Comment: 30 pages including 10 figures, LaTex, a revised version of SUBATECH 99-04 (aps1999_mar21_001) resubmitted to Phys. Rev. C; Chapter II made shorter, figure description made more clear, a comparison with most recent works added in Chapter V

Correlation femtoscopy

“…As for f , it increases with energy and for central lead-lead or gold-gold collisions seems to saturate at the highest SPS energy [33,45] (see, however, [46]). The saturated f is substantially smaller than unity for pions with p t > 0.2 Gev/c so pointing to negligible multiboson effects (see, e.g., [47,48]) in this p t -region.…”

Multipion Bose-Einstein correlations inpp,p-Pb, and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

“…(6) Multipion distortions. At high freeze-out phase-space density, all higher-order symmetrizations, which are usually neglected, can contribute significantly to all orders of correlation functions [49][50][51][52][53]. The distortions have been calculated for two-pion correlations and recently for three-and four-pion correlations [19].…”

“…The collision centrality in Pb-Pb is determined by using the charged-particle multiplicity in the V0 detectors [26]. Approximately 13,52, and 34 million events are used for pp, p-Pb, and Pb-Pb collisions, respectively.…”

Finite-size effect on two-particle production in continuous and discrete spectrum

“…Consider as an example the particle emission by independent one-particle emitters of various types A according to the one-particle production amplitudes (see also [31])…”

“…Particularly, for a Gaussian distribution of the mean emission three-momentum p A of a width ∆ 0 , (62) is modified by the substitution [31] …”