The coherent elastic reaction K + d → K + d and the break-up reaction K + d → K + pn are studied in a K + d experiment at 4.6 GeV/ c which the CERN 2 m bubble chamber. Partial and differential cross sections are given and the slopes of the differential cross sections are determined. The results for the reaction K + d → K + p(n s ), where n s denotes the spectator neutron, are compared with those of the reaction K + p → K + p on free protons. Combining our data with existing data on the reactions K + d → K 0 pp and K + p → K + p, parameters of the elastic K + -nucleon scattering at 4.6 GeV/ c are determined in the framework of the Glauber model. The D-wave of the deuteron and spin-flip effects are taken into account.
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Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s = 5-11 and -t = 2-7 GeV2 with statistical accuracy of a few percent. The scaling power for the s-dependence of the cross section at fixed center of mass angle was found to be 8.0 +/ 0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.
Cross section of proton Compton Scattering at centre of mass energy squared of 4.82 GeV.
Cross section of proton Compton Scattering at centre of mass energy squared of 6.79 GeV.
Cross section of proton Compton Scattering at centre of mass energy squared of 8.90 GeV.
Differential cross sections of proton Compton scattering have been measured at the Bonn 2.5 GeV synchrotron. The experiment covers photon laboratory energies between 1.2 GeV and 1.7 GeV and the square of the four-momentum transfer ranges fromt=−0.17 GeV2 to −0.98GeV2 corresponding to c.m. scattering angles between 35° and 80°. The cross sections exhibit a forward peak followed by a monotone fall-off up to the largest measured |t|-values. Fits of the formdσ/dt=A·exp(Bt) to the data points with |t|≦0.5 GeV2 yield forward cross sectionsA, which are consistent with the 0° cross sections calculated from the measured total photon-proton cross section. The average slope isB=5.6±0.14 GeV2.
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Neutron-proton differential cross sections have been measured with good statistics for four-momentum transfers 0.14<−t≲19.0 (GeV/c)2 at laboratory momenta ranging from 4.5 to 12.5 GeV/c. The experiment was carried out in a neutron beam at the Argonne National Laboratory zero-gradient synchrotron. These results in conjunction with previous n−p charge-exchange data provide almost complete elastic-scattering angular distributions in this momentum range.
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We have measured elastic scattering of 5 and 6 GeV photons on hydrogen and deuterium in the angular range 10–50 mrad. On hydrogen we observe a forward diffraction peak with a slope of 8.5 (GeV/ c ) −2 . The extrapolated forward cross sections in units μ b/(GeV/ c ) 2 are 0.82 ± 0.04 at 5 GeV and 0.79 ± 0.04 at 6 GeV. They are consistent with the calculated amplitudes obtained from total cross section measurements via the optical theorem and dispersion relations assuming negligible contributions of spin-dependent amplitudes. Deuterium cross sections show a transition from coherent scattering at low | t | to incoherent scattering at higher | t |. They indicate that the isovector exchange amplitude a 1 is very small compared to the isoscalar a 0 . We obtain |a 1 | 2 /|a 0 +a 1 | 2 =0.13±0.09 , Re (a 0 a ∗ 1 )/|a 0 +a 1 | 2 =0.0±0.03, at 5 GeV , |a 1 | 2 /|a 0 +a 1 | 2 =−0.12±0.15 , Re (a 0 a ∗ 1 )/|a 0 +a 1 | 2 =0.10±0.04, at 6 GeV .
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Photons of 3 GeV and 5 GeV were scattered on 7 different elements, ranging from Be to Au, and detected with a pair spectrometer. The angular distributions show diffractive patterns consistent with known nuclear sizes. Forward cross sections are 20–30% lower than expected from an A 2 dependence. This shadowing effect is qualitatively explained by photon interactions via intermediate hadronic states.
SYS ERR = 3.01 PCT, NORM ERR = 1.63 PCT.
SYS ERR = 2.94 PCT, NORM ERR = 1.60 PCT.
SYS ERR = 5.58 PCT, NORM ERR = 1.61 PCT.
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