A very narrow resonance with a mass of 3.1 GeV/c2 is observed in the reaction n+Be→μ++μ−+X. The total cross section for this process, as well as its P⊥2 and x distribution, are given.
The cross section per nucleon times the branching ratio.
A very narrow resonance with a mass of 3.105 GeV/c2 is observed in the reaction γ+Be→μ++μ−+X. The total cross section for this process, as well as its t distribution, is given.
THIS IS CROSS SECTION PER BERYLLIUM NUCLEUS ASSUMING ONLY COHERENT OR QUASI-ELASTIC SCATTERING FROM A SINGLE NUCLEON. FORWARD DIFFERENTIAL CROSS SECTIONS QUOTED IN TABLE 1 OF T. NASH ET AL., PRL 36, 1233 (1976).
An experiment was done in the external proton beam of the Berkeley 184-in. cyclotron to measure the production cross sections for pions from various target nuclei, from hydrogen to lead. The cross-section data are presented and the reaction mechanisms discussed. The hydrogen production appears to fit the one-pion-exchange model.
No description provided.
We have observed diffraction dissociation of KL0 mesons with a carbon target into the exclusive final states KS0π+π−, KS0ω, and KS0φ. The diffraction production cross section for these states is not strongly dependent on the incident energy, varying at most by 30% between 75 and 150 GeV. The mass distributions do not change appreciably as a function of laboratory energy. The ratio of the diffractive mass-threshold production of K*±π∓, KS0ρ, KS0ω, and KS0φ is compared with previously obtained lower-energy data.
TP (=T-TMIN) distribution for K0S PI+ PI- events satisfying the diffractive cuts.
TP distributions for K0S OMEGA and K0S PHI events which satisfy the diffractive cuts.
CROSS SECTIONS PER NUCLEUS.
We have measured the xF and PT dependence of the polarization of Λ0 hyperons produced in exclusive final states pp→pΛ0K+π+π−, pp→pΛ0K+π+π−π+π−, pp→pΛ0K+π+π−π+π−π+π−, and pp→pΛ0K+π+π−π+π−π+π−π+π− at 27.5 GeV/ c. We present an empirical parametrization for Λ0 polarization as a function of xF and PT: P=(−0.443±0.037)xFPT for −1≤xF≤1 and 0≤PT≤1.8GeV/c. This parametrization is independent of the final state and provides a good description of the data. We note that the mechanism responsible for Λ0 polarization appears to be independent of the production mechanism.
Result of a linear fit to all the data in the XL and PT region.
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No description provided.
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No description provided.
No description provided.
A structure has been observed at 2220 MeV in the mass spectrum of ηη ′ systems produced by 38GeV/ c and 100 GeV/ c ′ negative pions on protons. The angular distribution of the decay products shows that this structure is presumably a spin J ⩾ 2 meson.
No description provided.
No description provided.
We report results from a study of Λ0 polarization in the exclusive reaction pp→pf(Λ0K+) at 800−GeV/c. We observe a dependence of the polarization on the Λ0K+ invariant mass with large (+71%) positive polarization at small mass (1.63−GeV/c2) and large (−43%) negative polarization at large mass (2.75−GeV/c2). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Λ0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Λ0K+ system.
The measured LAMBDA polarisation as a function of the (LAMBDA K+) invariantmass.
The measured LAMBDA polarisation as functions of the LAMBDA transverse momentum and Feynman X.
We report the first observation of diffractively produced open charm in 800−GeV/c pp collisions of the type pp→pD*X. We measure cross sections of σdiff(D*+)=(0.185±0.044±0.054)μb and σdiff(D*−)=(0.174±0.034±0.029)μb. Our measurements are based on 4.3×109 events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.
No description provided.