A study of inclusive Ξ − production from a high statistics K − p experiment at 4.2 GeV/ c has been made. The total Ξ − production cross section is 157 ± 8 μ b. Approximately 15% of the Ξ − arise from decay of the Ξ ∗0 (1530) resonance. The polarization of the Ξ − is found to be negative and is nearly equal in value to that of the Λ 0 from the inclusive reaction K − + p → Λ 0 + anything. An analysis of the inclusive production of Ξ − has been made in the framework of the triple-Reege formalism.
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A study of the inclusive production of π − , η , ϱ 0 , ω ad f mesons in p p annihilation at 0.7 GeV/ c is presented. Topological and channel cross sections are determined. Longitudinal and transversal momentum distributions of non-strange mesons are studied. It is deduced that nearly 48% of all negative pions arise from the decay of η , ϱ 0 , ω and f mesons.
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We discuss the structure of the momentum transfer distributions for the diffractive dissociation processes p → n π + , p → Δ ++ π − and K − → K 890 ∗0 π − . In the near-threshold mass region a clear break of slope is found around t ′KK ∼ 0.25 GeV 2 for the two baryonic channels, whereas no comparable structure is seen for the mesonic system. The K → K ∗ π differential cross section exhibits a nearly exponential behaviour up to t ′ pp ∼ 0.6 GeV 2 , falling over three orders of magnitude. The slope variations and breaks are strongly correlated both to the mass region considered and to the decay angle of the fragmentation system.
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A study of 205-GeV/c π−p interactions has been made with a 48 800-picture exposure in the bare Fermilab 30-inch hydrogen bubble chamber. The average number of charged particles produced per inelastic interaction is 7.99±0.06. The elastic cross section is 3.18±0.13 mb and the total cross section is 24.19±0.44 mb. The inclusive cross sections for neutral-particle production are: σ(γ)=171.3±15.3 mb, σ(KS0)=3.64±0.61 mb (x<0.3), σ(Λ)=1.71±0.34 mb (x<0.3), and σ(Λ¯)=0.59±0.23 mb (x<0.1). The average number of π0's produced per inelastic collision is consistent with a linear rise with the number of charged particles, and about equal to the number of produced π− or π+. The average number of K0's, Λ's, and Λ¯'s is consistent with very little dependence on the number of charged particles. General characteristics of neutral-particle production are presented and compared with other experiments. For each topology the produced neutral energy is ∼13 of the incident energy.
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We report the results of a precise measurement of the K−p→K¯∘n cross section between 515 and 1065 MeV/c in steps of 10 MeV/c. The statistical errors are less than 1%, a major improvement in accuracy over previous work. No evidence is found for the new I=1 K¯N resonances at 546 and 602 MeV/c reported recently by Carroll et al.
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We have measured the neutron-proton charge-exchange differential cross section in the momentum interval 60 to 300 GeV/c, with squared four-momentum transfers 0.002 to 0.8 (GeV/c)2. Independent of incident momentum, the data are characterized by a sharp forward peak of width 0.02 (GeV/c)2, followed by a shoulder and gentler falloff at higher momentum transfers.
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Differential cross sections for elastic K + p scattering have been measured at nineteen momenta between 0.7 and 1.9 GeV/ c . The data represent between 10 thousand and 20 thousand elastic events at each momentum and cover a wide range of scattering angles ( −0.98 ≲ cos θ ∗ ≲ 0.95 ). A computer controlled system of scintillation counters and acoustic spark chambers was used to detect the elastic events. Various internal consistency checks indicate that the absolute normalization of the data is accurate to within 2–3%. The cross sections show a smooth transition from an isotropic angular distribution to a dominant forward peak over the range covered by the experiment. Phase-shift analyses including these results show little evidence for a direct-channel resonance, and fitting the results by t - and u -channel exchange processes alone gives a good fit.
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We present results for the total cross section of e + e − annihilation into two hadrons at 1.6 GeV: σ ππ = σ KK = (1.8 ± 1.1) × 10 -33 cm 2 .From these values we obtain the time-like electromagnetic form factors these mesons: | F π | 2 = 0.24 ± 0.14 and | F K | 2 = 0.46 ± 0.26.
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We compare production of the low mass K π -resonances by K + and K − beams in the non-charge-exchange reactions K ± p → K 0 s π ± p at 10 GeV/ c . High statistics data, obtained with the same apparatus, allow extraction of the K ∗ (890) and K ∗ (1420) production amplitudes corresponding to unnatural and natural parity exchange in the t -channel. The NPE-part dominates in both charge states. Its t -dependence shows a strong crossover at t ≈ −0.3 (GeV/ c ) 2 for the K ∗ (1420). For the K ∗ (890) the crossover is weaker but it occurs at the same value of t . This behaviour can be explained by pomeron, f and ω Regge exchange contributions to the NPE amplitude. The UPE amplitudes agree, both in normalisation and t -dependence, with the expectations of π and B exchange as isolated from data for the charge exchange reaction K − p → (K − π + )n.
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The polarization parameter has been measured in K − p elastic scattering at eight incident beam momenta between 650 MeV/ c and 1071 MeV/ c throughout a center of mass angular range of −0.75 < cos θ ∗ < 0.85 . Experimental results and coefficients of Legendre polynomial fits to the data are presented and compared with other measurements and partial wave analysis.
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