Search

Significant differences are observed between forward-produced Δ ++ (1232) and Λ 0 's in pp interactions and their corresponding anti-particles in p p interactions, as expected from quark counting and single q q annihilation. A possible relationship between these results and the p p -pp total cross section difference is discussed.

pp and pp elastic scattering differential cross sections are presented for momentum transfer 0.6

We report Λ 0 -hyperon polarization measurements at the CERN intersecting storage rings from √ s of 31 to 62 GeV. P Λ 0 changes insignificantly, +(0.8±1.7)%, over this range of √ s . However, P Λ 0 is observed to grow with Feynman- x F and with transverse momentum. At an average p t of 1.1 GeV/ c , P Λ 0 depends linearly on x F and approaches −40% at x F =0.8.

We report results of an inclusive measurement of the charmed baryon, Λc, in the forward direction of proton-proton interactions with s =63 GeV . The signal, seen in the final state Λsπ+π+π−, has 6.0 σ significance with about 620 events on a large background and corresponds to a cross section times branching ratio of 2.84±0.50±0.72 μb for Feynman-xF > 0.5 in both hemispheres. Asymmetries are observed in the decay angular distributions which are characteristic of weak decays and have a combined 3.0 σ significance.

D(1285) and E/iota(1422) are observed in the diffractive dissociation process, pp→(pK 0 K +- π ± )p, with √ s =63Gev. The D(1285) is produced with dominant ±1 helicity. Several unusual features of the data suggest that the mesonic states result from gluonic interactions in the collision.

In an experiment at the CERN intersecting storage rings with √s = 31 GeV, we have measured αP, the product of asymmetry parameter and polarization, for Λ 0's and Λ0's produced in p p and pp interactions, respectively. The ratio, (αP) Λ /(αP Λ = −1.04±0.29 , is consistent with the value −1, and constitutes the first test of CP invariance in Λ decay.

We study the production of π+'s and protons at 90° with pt>1.15 GeV and their correlations with forward protons. Fewer forward protons are observed for a 90° proton trigger than for a π+ trigger. This is in qualitative agreement with the idea of an effective diquark scattering mechanism. Additionally, we observe that a K+ produced at 90° is correlated with an enhanced forward production of λO.