F. Verbeure

Estimation of hydrodynamical model parameters from the invariant spectrum and the Bose-Einstein correlations of π− mesons produced in (π+/K+)p interactions at 250 GeV/c

Abstract The invariant spectra of π − mesons produced in ( π + /K + )p interactions at 250 GeV/ c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity 〈 u t 〉=0.20±0.07, and is characterized by a large temperature inhomogeneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140±3 MeV and 82±7 MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be Δη =1.36±0.02. Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of 〈 τ f 〉=1.4±0.1 fm/ c and its transverse geometrical rms radius, R G (rms)=1.2±0.2 fm.The invariant spectra of pi- mesons produced in (pi+/K+)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity= 0.20(7), and is characterized by a large temperature inhomogeneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140(3) MeV and 82(7) MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be Delta eta = 1.36(2). Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of= 1.4(1) fm/c and its transverse geometrical rms radius, R_G (rms)=1.2(2) fm.

Genuine higher-order correlations in π+p and K+p collisions at 250 GeV/c

Abstract Genuine higher-order correlations could be established up to fifth order in multiparticle production in π + p and K + p collisions at 250 GeV/ c . At decreasing interparticle distance in variant phase-space, these correlations follow approximate power-law scaling. The scaling behavior is different for non-exotic and like-charge particle combinations. It cannot be reproduced by FRITIOF without Bose-Einstein correlations. Including Bose-Einstein correlations according to JETSET7 reproduces the slope of like-charge two-particle correlations, but overestimates those of the higher orders.

Erraticity analysis of multiparticle production in π+p and K+p collisions at 250 GeV/c

Abstract The erraticity behavior of multiparticle production is analyzed in π + p and K + p collisions at 250 GeV/ c . It is demonstrated that, for these low-multiplicity final states, the erraticity measure based on event-to-event fluctuation of factorial moments is dominated by statistical fluctuations.

Collective sea-gull effect in π+p interactions at 250 GeV/c

Abstract A collective “sea-gull” effect is observed for a system of fast hadrons produced in the fragmentation regions of nondiffractive π + p -interactions at 250 GeV/ c . The effect is not reproduced by the FRITIOF fragmentation model in its details. It is demonstrated that hard-like processes, both in the collision phase and in the fragmentation phase, are not properly treated in the model.

Invariant Mass Dependence of Particle Correlations in Pi(+)P and K(+)P Interactions at 250 Gev/C

We study two- and three-particle correlations as a function of invariant mass. Using data on π+p andK+p collisions at 250 GeV/c, we compare correlation functions and normalised factorial cumulants for various charge combinations. Strong positive correlations are observed only at small invariant masses. The normalised cumulants for “exotic” [(−−), (++)] and “nonexotic” pairs (+−) and triplets decrease in power-like fashion with increasing invariant mass. The mass dependence is not incompatible with the power-law behaviour as expected in a Dual Mueller-Regge framework. Comparison with FRITIOF reveals strong disagreements, which are due to too large production rates of resonances, such as ρ0 and η, and the absence of a Bose-Einstein low-mass enhancement in JETSET.