The differential cross sections for K − p and p p elastic scattering have been measured over the range of four-momentum transfer squared 0.18<− t <3.3 (GeV/ c ) 2 . The K − p data decrease smoothly as a function of − t , whereas, the p p data shows a break at − t = 0.6 (GeV/ c ) 2 followed by a fast drop to − t ≅ 1.6 (GeV/ c ) 2 where the differential cross section levels off and stays constant out to − t = 3 (GeV/ c ) 2 .
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We have searched for resonance production in the reaction γγ→Ks0Kπ. No signal was found for theηc and an upper limit for the radiative with\(\Gamma _{\gamma \gamma }^{\eta _c } \) keV (95% c.l.) is obtained. For the glueball candidate η(1440) (previouslyi) the upper limit\(\Gamma _{\gamma \gamma }^{\eta (1440)} B(\eta (1440) \to K\bar K\pi )< 1.2keV(95\% c.l.)\) is derived. In the tagged data sample resonance formation of a spin 1 state at 1420 MeV is observed, which is absent in the untagged data. The mass and width of this state are consistent with those of thef1(1420); an analysis of decay angular distributions favours positive parity.
Data read from graph.. Additional overall systematic error decreasing from 25% in the lowest mass bins to 15% for M > 2.0 GeV.
An experiment has been completed at the Daresbury synchrotron to measure the asymmetry in the photoproduction cross section of neutral pions on hydrogen, for photons polarised normal to and in the production plane. The source of polarised photons was coherent bremsstrahlung of electrons traversing the lattice structure of diamond and the polarisation P of the γ beam was calculated from the measured intensity of the coherent spike. The asymmetry parameter Σ, defined as Σ = ( σ ⊥ − σ |)/( σ ⊥ + σ |) where σ ⊥( σ |) are the cross sections for photons polarised perpendicular (parallel) to the production plane, has been measured over a range of photon energies from 1.2 to 2.8 GeV and over a range of − t (the square of the four-momentum transfer) from 0.13 (GeV/ c ) 2 to 1.4 (GeV/ c ) 2 . A marked energy variation in the value of Σ is found over the energy region 1.6–1.8 GeV.
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
A partial-wave analysis of the K 0 π + π − system from the reaction K − p → K 0 π + π − n has been carried out using data obtained at 8.25 GeV/ c in a high-statistics experiment. A strong signal appears in the 1 + SO + (K ∗ π) wave at the Q 2 mass (≈ 1.4 GeV). The 1 + S0 + (ϱK) wave behaves rather like a background and does not exhibit the characteristics of a resonance. A prominent signal also appears in the 2 + D wave (via K ∗ π and ϱK); it is interpreted as the K ∗ (1430). In the L region (1.6–2.1) GeV, there is evidence for the 3 − K ∗ (1780) while the 2 − wave also gives some contribution.
FULLY CORRECTED CROSS SECTION.
RESONANCE FITS CROSS SECTIONS USING BREIT WIGNER FUNCTION. NOTE THAT FOR THE K*(1780) THE CROSS SECTION DETERMINATION IS STRONGLY DEPENDENT ON THE BACKGROUND ASSUMED WHICH HAS BEEN ONLY SUBTRACTED AT 8.25 GEV.
The production ofK* resonances has been studied in the reaction\(K^ -p \to \bar K^0 \pi ^ -p\) at 8.25 GeV/c. The data comes from a high statistics bubble chamber experiment (180 events/μb). Masses, widths and production cross-sections have been determined for the first threeK*'s. The contributions from natural and unnatural parity exchange have been obtained for theK*(890) and theK*(1420). A partial wave analysis of theK π system from threshold to 1.9 GeV provides evidence for a 0+ enhancement near 1.4 GeV which could be interpreted as the κ(1350).
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FULLY CORRECTED.
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The dissociation of a K− into the K−ϕ system is studied at 8.25 GeV/c. The cross-section for K−ϕp production is (27±2) μb. All the expected properties of diffraction are found (mass spectrum, mass-slope correlation, 1+S wave dominance). There is also an indication of the Kϕ decay mode of a 2− resonance in theL region.
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Inclusive Λ production has been studied in K − p interactions at 8.25 GeV/ c using about 69 000 events; the total cross section is found to be 3.35 ± 0.20 mb. A comparison has been made with Σ 0 and Σ(1385) inclusive production. Their influence on the inclusive Λ production is discussed. The inclusive Λ cross section and polarization is interpreted in terms of the triple-Regge model. In the target fragmentation region an effective Regge trajectory is determined which lies closer to the K than to the K ∗ . In the beam fragmentation region the cross-section data indicate an effective Regge trajectory which corresponds to the nucleon, while the polarization data require additional Regge exchanges to be present.
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Inclusive Ξ − production is studied in K − p interactions at 8.25 GeV/ c using about 8000 events. An analysis based on the triple-Regge model shows that the Λ α − Λ γ and Σ β − Σ δ exchanges explain the forward Ξ − production. Ξ(1530) properties are also studied and are found to be similar to those of Ξ − 's. Finally, a study of the production of Ω − based on 67 events shows that Ω's are also produced by hyperon exchange.
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We present results on the differential cross-sections for the reactions π + p → K + Σ + (1385) and K − p → π − Σ + (1385) at 10 GeV/ c . For the first time, the same equipment has been used in measuring both reactions, in order to obtain good relative normalization. In the region of low t ( t min to −0.3 (GeV/ c ) 2 ) the two differential cross-sections have similar shape, and show a sharp forward dip indicating a dominant helicity flip contribution. However, the magnitudes of the cross-sections are significantly different, indicating substantial exchange degeneracy breaking. We find the ratio of the integrated cross-sections for the reactions K − p → π − Σ + (1385) and π + p → K + Σ + (1385) over the range −0.3 < t ′ < 0.0 (GeV/ c ) 2 to be 2.0 ± 0.2.
TMIN = -0.013 GEV**2.
TMIN = +0.012 GEV**2.
The reaction p p → π − π + has been studied at 10.1 GeV/ c in the − t interval from 0.15 to 1.5 (GeV/ c ) 2 . A line-reversal comparison with backward elastic scattering π + p → p π + shows good agreement for − t > 0.3 (GeV/ c ) 2 .
No description provided.
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