H. Böttcher

Intermittency patterns in π+p and K+p collisions at 250 GeV/c

Abstract Intermittent behaviour is observed in π + p and K + p collisions at 250 GeV/ c . It is stronger there than in O 16 emulsion, but weaker than in e + e − collisions. A jet cascading mechanism is, therefore, the most likely interpretation. Presently used fragmentation models do not (fully) reproduce the effect, suggesting that an improvement of the hadronization picture is needed.

Intermittency effects in π+p and K+p collisions at 250 GeV/c

Abstract Density fluctuations are studied in rapidity, pseudo-rapidity and azimuthal angle, as well as in two-dimensional distributions in rapidity and azimuthal angle. Evidence for intermittency, i.e. rise of factorial moments with increasing resolution, is found in all four distributions. Intermittency is stronger in two dimensions than in one, but the difference is smaller than would be expected from the production of “pencil jets”. Contrary to what would be expected from Bose-Einstein interference, no increase by a factor 2 is found in slope when the analysis is restricted to particles of identical charge.

Factorial moments, cumulants and correlation integrals in Pi+P and K+P interactions at 250 Gev/C

AbstractA selected sample of 59200 π+p andK+p nonsingle-diffrative interactions at

Influence of multiplicity and kinematical cuts on Bose-Einstein correlation in Pi+ P-interactions at 250 Gev/C

\sqrt s

Neutral kaon production inK+p and π+p interactions at 250 GeV/c

=22 GeV is used to investigate one, two- and three-dimensional factorial moments, factorial cumulant moments, as well as correlation integrals. The rise of factorial moments and cumulants with decreasing phase-space volume is stronger when evaluated in three than in lower dimensions. Ratios of slopes are easier to obtain than the slopes themselves. Contrary to earlier findings, they turn out to depend on the dimension. The order dependence of the averaged ratios is better described by a Lévy stable law solution with μ=1.6 than by Gaussian approximation of the α-model (μ=2) or a second order phase transition (μ=0), but values μ>2 inconsistent with Lévy-type fluctuations are reached in a three-dimensional analysis. The multiparticle contributions to the factorial moments are calculated by means of factorial cumulant moments. A particular improvement of the method is that of correlation (or density) integrals. It leads to the conclusion that Bose-Einstein interference plays an important role in the intermittency effect, but indication is found for an interpretation alternative to the conventional view of Bose-Einstein correlations.

Multiplicity distributions in separated phase space intervals of π+p collisions at 250 GeV/c

Abstract Density fluctuations are studied in rapidity, separately for low and intermediate transverse momentum particles. In our data, the effect of intermittency is increased when the analysis is restricted to low p T particles.

Multiplicity dependence of the average transverse momentum in π+ p, K+ p and pp collisions at 250 GeV/c

The correlation of negative particles at small momentum difference and its dependence on multiplicity and on kinematical cuts is studied in π+p-interactions at 250 GeV/c. In terms of the Kopylov-Podgoretskiį parametrization, an average radius of the pion emitting region ofrK=1.59±0.14 fm and a life-time (or emission depth) τ=0.83±0.25 fm are found. The Lorentz invariant parametrization of Goldhaber givesrG=0.85±0.04 fm. Assuming two different sources of pions, their radii are estimated asr1=1.75±0.25 fm andr2=0.60±0.08 fm. An angular and multiplicity dependence of the space-time size of the source is observed. The source is elongated along the collision axis and has larger sizerK at higher multiplicities. The radiusrK decreases with increasing pion pair momentum. The size of the emitting region appears to be larger for low rapidity pions than for pions from the fragmentation region. No evidence is found for a unique reference frame, where the pion source is motionless for each π+p collision, i. e. where the space-time size of the source is definitely smaller than in any other frame.

Collective characteristics of hadron systems produced in beam fragmentation of π+p collisions at 250 GeV/c

Two- and three-particle rapidity correlations are analyzed inK+p and π+p-interactions at 250 GeV/c. The main contribution to the two- and three-particle correlation functions comes from mixing of events of different multiplicity. The (short range) two-particle correlation remaining after exclusion of mixing is significantly larger for (+−) than for the equal charge combinations, and is positive for a wider range in rapidity difference. FRITIOF and a 2-string DPM are excluded by our data. A quark-gluon (multi-)string model can describe our inclusive correlation function, but needs to be tuned on the short range part. The multiplicity mixing part increases much faster with increasing energy than the short range part. In the central region, our correlation is similar to that observed ine+e− and μp collisions at similar energy.