T. Haupt

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.

Maximum particle densities in rapidity space of π+ p, K+ p and pp collisions at 250 GeV/c

Abstract In a study of π + p, K + p and pp collisions at √ s =22GeV in the european hybrid spectrometer (EHS), the maximum charged particle density per given rapidity interval is found to rise linearly with charged particle multiplicity, independent of beam particle type and practically independent of energy between 22 and 900 GeV. An anomalous π + p event is found with ten particles within the very narrow rapidity interval Δy =0.098.

Charged particle production inK + p, π p andpp interactions at 250 GeV/c

New results are reported on inclusive charged particle production inK+p,π+p andpp collisions at 250 GeV/c. Inclusive longitudinal and transverse momentum spectra of positively and negatively charged particles are presented. Scaling in the fragmentation regions and scaling violation in the central c.m. region is investigated in detail. The topological pseudo-rapidity densities are shown to scale in the c.m. energy range from 22 to 900 GeV.

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.

Single diffraction dissociation inπ+ andK+p interactions at 250 GeV/c

AbstractResults on inclusive single diffraction dissociation inπ+ andK+p interactions at 250 GeV/c are presented for excited masses up to ≃9 GeV. Total and topological cross sections for meson and proton diffraction are determined and their energy dependence is studied. For meson diffraction, hadronization of the diffractive system is well described by a MC model with

Inclusive production of vector mesons in π+p interactions at 250 GeV/c

q\bar q

Low pT intermittency in π+ p and K+ p collisions at 250 GeV/c

-Lund fragmentation and is found to be similar to hadronization ine+e−, annihilation in terms of thrust and mean charged multiplicity. Fireball-like decay models can be excluded from an elongation of the meson system along the beam-pomeron axis.

Inclusive meson resonance production inK+p interactions at 250 GeV/c

Inclusive production of direct soft photons is studied inK+p andK+π interactions at 250 GeV/c. Total cross sections, Feynman-x and transverse momentum distributions of direct γs are presented. The measured cross sections are several times larger than expected from QED inner bremsstrahlung, indicating the presence of an anomalous soft photon source. The model of Lichard and Van Hove, based on the “cold quark-gluon plasma” picture, agrees with the data.