Elastic and charge-exchange K + n differential cross sections have been measured from K + d interactions from 430 to 940 MeV/ c using spark chambers and scintillation counters. The data have been compared with existing results and in an accompanying paper have been included with other measurements in a phase-shift analysis.
DEUTERIUM TARGET.
NOTE COHERENT ELASTIC SCATTERING ON DEUTERIUM AT FORWARD ANGLES (-T < 0.13 GEV**2) REDUCES THE CROSS SECTION COMPARED WITH FREE NUCLEON ELASTIC SCATTERING.
NOTE COHERENT ELASTIC SCATTERING ON DEUTERIUM AT FORWARD ANGLES (-T < 0.13 GEV**2) REDUCES THE CROSS SECTION COMPARED WITH FREE NUCLEON ELASTIC SCATTERING.
We present results of a K − d experiment performed with the 81 cm Saclay deuterium bubble chamber which was exposed to a K − beam at 4 momenta between 680 and 840 MeV/ c at the CERN PS. Cross sections were measured for inelastic two- and three-body K − n reactions on the basis of 5200 events/mb. Resonance production in the three-body reactions is discussed. In addition, differential cross sections and polarisations are presented for inelastic two-body reactions.
CROSS SECTIONS FOR TWO-BODY REACTIONS.
CROSS SECTIONS FOR THREE-BODY REACTIONS.
CROSS SECTIONS FOR K- P REACTIONS.
Differential cross sections for K − n → Σ o π o have been measured at K − momenta between 680 and 840 MeV/ c in a bubble chamber experiment. For K − n → Σ o π − the Σ o polarization was also determined. The measurements were combined with the available data on K − p → Σπ in an energy-dependent partial wave analysis in the center of mass energy range from 1520 to 1745 MeV. An acceptable fit was obtained with the well established resonances.
FULL DETAILS OF THIS EXPERIMENT ARE IN V. HEPP ET AL., NP B115, 82 (1976), THE RECORD OF WHICH CONTAINS THE TABULATED TOTAL AND DIFFERENTIAL CROSS SECTIONS, POLARIZATIONS AND LEGENDRE POLYNOMIAL COEFFICIENTS.
Measurements are presented of the cross sections for ω meson photoproduction from deuterium at an average photon energy of 3.9 GeV. The cross section for the coherent process γ d → d ω is found to be 1.4 ± 0.5 μ b and that for the incoherent process γ d → np ω is 3.3 ± 0.7 μ b. The forward differential cross section for γ d → d ω is estimated to be (d σ /d t ) t =0 = 54 ± 20 μ b/GeV 2 . This result indicates that the value of the A 2 exchange amplitude in ω photoproduction from hydrogen is less than that predicted from the measurements of the difference between the total hadron photoproduction cross sections from neutrons and protons. We note that the world data tend to show that the A 2 exchange amplitude is more consistent with zero than with the value needed to explain these differences. Measurements are also presented of the ratio of the coupling constants of the photon to the ϱ and ω mesons which tend to favour the vector dominance model proposed by Das, Mathur and Okubo with exact SU(3) symmetry at infinite energies.
AVERAGE OF TWO INDEPENDENT DATA SAMPLES AND ANALYSIS PROCEDURES.
We have measured the backward differential cross section in π−p elastic scattering at 31 momenta from 1.28 to 3.0 GeV/c. These measurements covered the center-of-mass angular range of 125°-178° corresponding to −0.570≲cosθc.m.≲−0.999. Considerable structure in the angular distribution is found. We compare these data with data from other experimets and to predictions made by the latest phase-shift solution. We find, in general, good agreement with other data in the few regions of overlap. The fits from the phase-shift solution do not accurately reproduce these data at low momenta below 1.9 GeV/c but give excellent agreement above this momentum.
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In a single-arm spectrometer experiment, high-precision measurements of dσdt for π−p, K−p, and p¯p elastic scattering have been made at 8 and 16 GeV/c. The π−p data show rich structure at 8 GeV/c, indicative of strong non-Pomeron contributions, while the 16-GeV/c data are much smoother. For −t≳1 (GeV/c)2 there is a strong s dependence while there is very little for −t<1 (GeV/c)2. For p¯p scattering the forward region is smoothly diffractive for −t<0.4 (GeV/c)2 and shows antishrinkage. The exponential slope parameter b is measured to be 12.36 ± 0.04 (GeV/c)−2 at 8 GeV/c and 11.40 ± 0.04 (GeV/c)−2 at 16 GeV/c. The structure near −t=0.6 (GeV/c)2 seen at lower energies is still obvious at 16 GeV/c. The K−p data show some structure at 8 GeV/c, but can be represented adequately by a quadratic exponential form. At 16 GeV/c the K−p angular distribution shows antishrinkage and lies above the 8-GeV/c cross section for 0.11<−t<0.8 (GeV/c)2.
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As part of a program of measurements of the πp system we have measured the backward differential cross section for π+p elastic scattering at 16 momenta from 1.25 to 2.0 GeV/c inclusive. The angular region covered is -0.46 to -0.97 in cosθc.m.. The high resolution in u of 0.03 to 0.04 (GeV/c)2, together with good statistics, enables a detailed examination of the momentum and angular dependence of structure in this channel. The data are compared with distributions from other experiments and with the most recent phaseshift fit.
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Elastik K − n ( I = 1) differential cross sections have been measured at 14 momenta between 610 and 940 MeV/ c , over the c.m. angular range −0.7 < cos θ ∗ < 0.8 . The results, which cover the c.m. energy range 1610–1765 MeV, have been fitted with Legendre polynomials and compared with some existing predictions from a partial-wave analysis.
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SEMI-INCLUSIVE CROSS SECTION.
The reactions K − d→ Σ − p, K − d→ Σ − (1385)p, K − d→ Λ (1405)n and K − d→ Λ (1520)n have been studied at K − momenta between 686 and 844 MeV/ c in an experiment with the 81 cm Saclay bubble chamber at CERN. About 630 000 pictures have been analyzed. Partial and differential cross sections are presented. A one-nucleon-exchange model is used to extract the kaon-nucleon-hyperon coupling constants from these results. For g( K N Σ(1197)), g( K N Σ(1385)) and g( K N Λ(1405)) we find values which are compatible with the SU(3) predictions. The coupling constant g( K N Λ(1520)) obtained by our method agrees with that determined from the partial decay width for Λ(1520)→ K N .
CROSS SECTIONS FROM FITTING WITH BREIT-WIGNER DISTRIBUTIONS AND SMOOTH BACKGROUND.
CROSS SECTION WITH A T-CUT.
CROSS SECTION WITH A T-CUT.
Measurements are presented of the cross sections for omega meson photoproduction at a mean energy of 3.9 GeV from nuclear targets of D, Be, C, Al, Cu, Ag, Au. An optical and Glauber model analysis of the coherent cross sections has been performed to obtain the ω-nucleon cross section, σ ωN , and the photon-omega coupling constant γ ω 2 /4 π . Our results are summarised in table 4. We find good agreement with the quark model prediction that σ ω N = σ ϱ N , and with the value of γ ω 2 /4 π determined from the storage ring experiments and from an earlier complex nuclei measurement. However, we disagree with more recent complex nuclei measurements which found a high value of γ ω 2 /4 π .
COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.
COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.
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