Charged particle production in the Pb+Pb system at 158 GeV/c per nucleon

Charged particle multiplicities from high multiplicity central interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured in the central and far forward projectile spectator regions using emulsion chambers. Multiplicities are significantly lower than predicted by Monte Carlo simulations. We examine the shape of the pseudorapidity distribution and its dependence on centrality in detail.Comment: 17 pages text plus 12 figures in postscript 12/23/99 -- Add TeX version of sourc

Observation of Scaling Violations in Scaled Momentum Distributions at HERA

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of $x$ and $Q^2$ using the ZEUS detector. The evolution of the scaled momentum, $x_p$, with $Q^2,$ in the range 10 to 1280 $GeV^2$, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of $Q^2$.Comment: 21 pages including 4 figures, to be published in Physics Letters B. Two references adde

Proton distributions in the target fragmentation region in proton - nucleus and nucleus-nucleus collisions at high-energies

We present measurements of the rapidity and transverse-momentum distributions of the protons emitted in S + W, O + W, and p + W reactions at 200 GeV/A around the target rapidity (y = 1). The rapidity density rises linearly with the transverse energy for all three systems, but the slope for p + W is much steeper than for O + W and S + W. The rapidity density for p + W is much higher than predicted by summing single nucleon-nucleon collisions without any nuclear effects, indicating substantial rescattering of the produced particles. The predictions of the VENUS 3 model, including rescattering, show reasonable agreement with the data for all three systems. We do not have evidence for a strong collective flow of the outgoing particles

Measurement of deeply virtual Compton scattering at HERA

The cross-section for deeply virtual Compton scattering in the reaction ep → eγp has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb −1 of e + p and 16.7 pb −1 of e − p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q 2 , and the centre-of-mass energy, W , of the γ ∗ p system in the region 5< Q 2 <100 GeV 2 and 40< W <140 GeV. The measured cross-sections rise steeply with increasing  W . The measurements are compared to QCD-based calculations