arXiv subjects
Publications and source records attributed to A. Bialas.
An explicit analytic formula for the transverse and longitudinal impact factors S_{T,L}(N,γ) of the photon using k_T factorization with exact gluon kinematics is given. Applications to the QCD dipole model and the extraction of the unintegrated gluon structure function from data are proposed.
It is shown that the colour dipole approach to hard scattering at high energy is fully compatible with k_T factorization at the leading logarithm approximation (in -log x_Bj). The relations between the dipole amplitudes and unintegrated diagonal and non-diagonal gluon distributions are given. It is also shown that including the exact gluon kinematics in the k_T factorization formula destroys the conservation of transverse position vectors and thus is incompatible with the dipole model for both elastic and diffractive amplitudes.
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.
An algorithm for measurement of entropy in multiparticle systems, based on recently published proposal of the present authors, is given. Dependence on discretization of the system and effects of multiparticle correlations are discussed in some detail.
It is shown that that Gaussian fluctuations of the string tension can account for the "thermal" distribution of transverse mass of particles created in decay of a colour string.
The coincidence method of measuring the entropy of a system, proposed some time ago by Ma, is generalized to include systems out of equilibrium. It is suggested that the method can be adapted to analyze multiparticle states produced in high-energy collisions.
Multivariate density moments (correlators) of arbitrary order are obtained for the multiplicative self-similar cascade. This result is based on the calculation by Greiner, Eggers and Lipa (reference [1]) where the correlators of the logarithms of the particle densities have been obtained. The density correlators, more suitable for comparison with multiparticle data, appear to have even simpler form than those obtained in [1].
Event-by-event observables are compared with conventional inclusive measurements. We find that moments of event-by-event fluctuations are closely related to inclusive correlation functions. Implications for upcomming heavy ion experiments are discussed.
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 $t^2 - z^2 = τ_0^2$.
Introductory talk at the Session on Correlations and Fluctuations of the XXVII International Symposium on Multiparticle Dynamics held in Delphi, Greece, from 6th till 11th of September 1998.
Using the QCD dipole picture of BFKL dynamics, the quasi elastic component of the diffractive gamma*-dipole cross-section, dominating at small M^2/Q^2, is calculated.
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.
We propose to use the coincidence method of Ma to measure an entropy of the system created in heavy ion collisions. Moreover we estimate, in a simple model, the values of parameters for which the thermodynamical behaviour sets in.
Forward differential cross-section for diffraction dissociation of virtual photons on nucleon target is calculated in the QCD dipole picture. The numerical estimates are presented and discussed.
It is pointed out that the recent data on strange baryon and antibaryon production in Pb-Pb collisions at 159 GeV/c agree well with the hypothesis of an intermediate state of quasi-free and randomly distributed constituent quarks and antiquarks. Also the S-S data are consistent with this hypothesis. The p-Pb data follow a different pattern.
Summary talk at the VIIIth International Workshop on Multiparticle Production "Correlations and Fluctuations '98" held at Matrahaza, Hungary, from 14th till 21st of June 1998.
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.
We discuss the possibility to measure entropy of the system created in heavy ion collisions using the Ma coincidence method.