arXiv subjects
Publications and source records attributed to K. Zalewski.
A group of transformations changing the phases of the elements of the single-particle density matrix, but leaving unchanged the predictions for identical particles concerning the momentum distributions, momentum correlations etc., is identified. Its implications for the determinations of the interaction regions from studies of Bose-Einstein correlations are discussed.
It is pointed out that the moments of phase-space particle density at freeze-out can be determined from the coincidence probabilities of the events observed in multiparticle production. A method to measure the coincidence probabilities is described and its validity examined.
A group of transformations changing the phases of the single particle density matrix, but leaving unchanged the predictions for identical particles concerning the momentum distributions, momentum correlations etc., is identified. Its implications for the determinations of the interaction region from studies of Bose-Einstein correlations are discussed.
Effects of quantum statistics are clearly seen in the final states of high-energy multiparticle production processes. These effects are being widely used to obtain information about the regions where the final state hadrons are produced. Here we briefly present and discuss the assumptions underlying most of these analyses.
Multiparticle effects in Bose-Einstein correlations are reviewed. It is shown that for a broad class of models they can be ignored in the low density limit, but often are significant (typically at the 10% level) for realistic denisties.
It is shown that, in the presence of correlations in particle emission, the measured HBT radii are related to the correlation range rather than to the size of the interaction volume. Only in the case of weak correlations the standard interpretation may be applicable, The earlier discussion [1] of short-range correlations in configuration space is generalized to include also the correlations of particle momenta.
The core/halo model describes the Bose-Einstein correlations in multihadron production taking into account the effects of long-lived resonances. The model contains the combinatorial coefficients alpha_j which were originally calculated from a recurrence relation. We show that alpha_j is the integer nearest to j!/e.
Data on Bose-Einstein correlations yield information about the interaction regions in multiple particle production processes. The conclusions are model dependent. Several popular models are briefly presented, compared and discussed.
Relations between Wigner functions and the source functions used in models of Bose-Einstein correlations in multiple particle production are derived and discussed. These relations are model dependent. In particular it is important whether the particles are emitted simultaneously and if not, whether the production amplitudes corresponding to different moments of time can interfere with each other.
A generating function for products of Hermite polynomials is used to significantly simplify the evaluation of the integrals G_m(p,p') occurring in the Gaussian model of multiple particle production. These integrals are crucial for studies of multiparticle effects in Bose-Einstein correlations.
Most models of Bose-Einstein correlations in multiple particle production processes can be ascribed to one of the following three broad classes: models based on the original idea of the Goldhabers, Lee nad Pais, hydrodynamic models and string models. We present for discussion some basic questions concerning each of these classes of models.
Mass dependence of the effective source radii, observed in hadronic $Z^0$ decays by several LEP I experiments, is analyzed in a model which assumes proportionality between four-momentum of a produced particle and the four-vector describing its space-time position at the freeze-out. It is shown that this relation (commonly accepted in description of high-energy collisions) can explain the data, provided all particles are emitted from a "tube" of $\sim 1$ fm in diameter at a constant proper time $\sim 1.5$ fm.
It is shown that the recently established strong mass- dependence of the radii of the hadron sources, as observed in HBT analyses of the $e^+e^-$ annihilation, can be explained by assuming a generalized inside-outside cascade, i.e. that (i) the four-momenta and the space-time position four-vectors of the produced particles are approximately proportional to each other and (ii) the "freeze-out"times are distributed along the hyperbola $t^2 - z^2 = τ_0^2$.
Local fluctuations of pion density in momentum space may lead to Bose-Einstein condensation. Conditions for this phenomenon to occur in in high-energy collisions and possibilities of its experimental investigation are discussed.
Bose-Einstein correlations are studied in the framework of a class of independent particle production models. This generalizes the studies for a variety of models proposed previously. It is shown that the Bose-Einstein correlations lead for this class of models to Einstein's condensation at sufficiently high density. They also enhance unusual charge distributions and may explain the centauro and anticentauro events reported by cosmic ray physicists. For typical models the correlations cause a shrinking of the momentum distribution of the produced identical particles and an apparent shrinking of the production region.
Recent results on effects of Bose-Einstein symmetrization in a system of independently produced particles are interpreted in terms of statistical physics. For a large class of distributions, the effective sizes of the system in momentum and in configuration space are shown to shrink when quantum interference is taken into account.
The influence of the HBT effect on the momentum spectra of independently produced pions is studied using the method developed earlier for discussion of multiplicity distributions. It is shown that in this case all the spectra and multiparticle correlation functions are expressible in terms of one function of two momenta. It is also shown that at the critical point all pions are attracted into one quantum state and thus form a Bose-Einstein condensate.
The influence of the HBT effect on the multiplicity distribution and charge ratios of independently produced pions is studied. It is shown that, for a wide class of models, there is a critical point, where the average number of pions becomes very large and the multiplicity distibution becomes very broad. In this regime unusual charge ratios ("centauros", "anticentauros") are strongly enhanced. The prospects for reaching this regime are discussed.