Coherent production ofρ − mesons in charged current antineutrino-neon interactions in BEBC

Coherent production ofρ ^? mesons in charged current antineutrino interactions on neon nuclei is studied in the BEBC bubble chamber exposed to the CERN SPS wide band beam. The cross section is measured to be (95±25)·10^?40 cm² per neon nucleus, averaged over the beam energy spectrum. The distributions of kinematical variables and the absolute value of the cross section are in agreement with theoretical predictions based on the CVC hypothesis and the vector meson dominance model.     

Evidence for higher twist effects in fast π− production by antineutrinos in neon

Evidence for a significant higher twist contribution to highz π^? production in antineutrino scattering is presented. In events withW>3 GeV andQ ²>1 GeV² in our data, it accounts for (51 ±8)% of all π^? withz above 0.5. It is consistent with thez?Q ² correlations of Berger's higher twist prediction. The data are inconclusive concerning the predictedy?z correlation andp _T dependence. Thez ?Q ² correlation is not adequately described by the Lund Monte-Carlo.     

A measurement of ∧ and Ξ<Superscript>−</Superscript> polarization in inclusive production by Σ<Superscript>−</Superscript> of 340 GeV/c in C and Cu targetsof 340 GeV/c in C and Cu targets

We have measured the polarization of ∧ and Ξ^? hyperons produced inclusively by a Σ^? beam of 340 GeV/c momentum in nuclear targets, using samples of 9.5 million ∧ decays and 880000 Ξ^? decays. The large statistics allowed a two-dimensional analysis as functions ofx _F andp _t . The polarization w.r.t. the production normal is mainly positive for ∧ and negative for Ξ^?. The positive sign of the ∧ polarization is opposite to predictions. Atp _t >1 Gev/c, the ∧ polarization decreases to zero or even negative values, in sharp contrast to the plateau abovep _t <1 GeV/c observed in inclusive ∧ production by protons. No such effect is observed for the Ξ^? polarization, and its sign is as expected.     

Transverse energy production in the target fragmentation region in16O-nucleus reactions at 60 and 200A GeV

Charged pion yields and transverse energies of baryons are measured for the reaction¹⁶O+Cu, Ag, Au at 60 and 200A GeV bombarding energy in the target fragmentation region employing the Plastic Ball detector. Only little dependence of the measured quantities on the bombarding energy is found. The data are compared with the multi-chain fragmentation model of Ranft. As a result it turns out that a leading order formation zone cascade is not sufficient to explain the baryon yield and the transverse energies of baryons in the target fragmentation region.     

High transverse momentum prompt photon production by π− and π+ on protons at 280 GeV/c

The inclusive cross sections for prompt photon production by π^? and π⁺ on protons have been measured with a beam momentum of 280 GeV/c using a fine grained electromagnetic calorimeter and the CERN Omega spectrometer. The transverse momentum and Feynmanx _F ranges covered are 4.0<p _T <7.0GeV/c and ?0.45<x _F <0.55 respectively. A quantitative comparison of the prompt photon cross section with next-to-leading order QCD predictions using Duke and Owens structure functions is performed.     

Oxygen-induced reactions at 60A GeV and 200A GeV studied by calorimetry

Results based on calorimetric measurements are presented from reactions of 60A GeV and 200A GeV¹⁶O projectiles with C, Cu, Ag, and Au nuclei. Minimum-bias cross sections are discussed. Energy spectra measured at zero degrees and transverse-energy distributions for the pseudorapidity range 2.4≦η≤5.5 are shown. An analysis of the average transverse energy in terms of the number of participating nucleons and the number of binary nucleon-nucleon collisions is presented. Estimates of nuclear stopping and of attained energy densities are made.     

Study of the centrally producedK 1 0 K ± π∓ system at 85 GeV/c

We have analyzed theK ₁ ⁰ K ^± π^? system in the reactions π⁺/pp→π⁺/p(K ₁ ⁰ K ^± π^?)p. A spin-parity analysis of theK ₁ ⁰ K ^± π^? system in the “4C” channel confirms the existence of the 1⁺⁺ E meson which decays mainly throughK ^* \(\bar K\) . The data allow the presence of a 0^?+ wave at a level of 14% of theE/ι signal. The production ofD andE mesons in the channels where theK ₁ ⁰ K ^± π^? system is produced along with a π⁰ or π⁺π^? system is suppressed.