The polarization of the proton from the inclusive breakup reaction 1 H( d , p )X at 2.1 GeV was measured at 0°. The results are expressed as the ratio of the proton polarization, P p , to the deuteron beam polarization, P d , κ 0 = P p / P d . The measured values of κ 0 range from +0.983 to -0.305 and are in general agreement with the expected behavior arising from the D state in the deuteron wave function.
POL(C=DEUT) is the DEUT polarization, the P(P=3,RF=ANTILAB) is the proton momentum in DEUT rest frame.
Average numbers of ϱ 0 , K ∗0 (890) and K ∗0 (890) produced in peripheral collisions (with the number of “grey” protons n g ⩽2) of K + with Al and of π + with Al and Au nuclei at 250 GeV/ c are measured in the EHS(NA22) experiment at the CERN SPS. No evidence is found for suppression of vector meson production relative to K + p and π + collisions at the same energy.
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We have measured the cross section for γγ production with the TOPAZ detector in the energy region √ s =50.0–61.4 GeV. The observed cross section for γγ production integrated over |cos θ | ⩽ 0.77 is 50.2±0.8±2.2 pb at 〈√ s 〉=57.6 GeV and the ratio of this value to the QED prediction is 1.01±0.02±0.04. The angular distribution is in good agreement with the QED predictions, thereby setting limits on the compositeness scales, Λ L+R + =168 GeV, Λ L+R − =97 GeV, Λ L,R =141 GeV, Λ L,R − =81 GeV, and Λ L−R ± =68 GeV, at the 95% confidence level. The reaction e + e − → γγγ was also studied and was found consistent with the QED prediction.
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We have measured the K + K - /π + π - ratio R from p annihilations in gaseous D 2 and H 2 at atmospheric pressure. The measurement was performed with the OBELIX spectrometer. From the measured value in gaseous D 2 (0.27±0.02) we infer a P wave contribution to p −p annihilation in D 2 of (18±7)%.
Two different triggers were used.
Data collected in the experiment R704 at the CERN ISR are used to study the annihilation process p p → π 0 π 0 at several centre-of-mass energies between 2.97 and 3.56 GeV. A total sample of 7359 events has been identified, from which cross sections and angular distributions in the interval 0 < | cos θ ∗ | < 0.5 have been measured.
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Analysing powers and differential cross sections for p p → π − π + and p p → K − K + have been measured over the full angular range using a polarised target at LEAR at 20 beam momenta from 360 to 1550 MeV/ c . Discrepancies in the normalisation of earlier d σ/ d Ω data at low momenta are clarified. Above 1000 MeV/ c , A 0N results confirm values close to +1 over most of the angular range for both reactions, in excellent agreement with earlier data of lower statistics. Below 1000 MeV/ c , where the analysing power is measured for the first time, large variations of A 0N with energy and angle are present.
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Backward emitted protons with momentump>0.3 GeV/c in interactions of neutrino in the energy range 10–200 GeV with photoemulsion nuclei were investigated. Energy spectrum slope parameter of backward protons was measured to beT0=48.9±7.9 MeV. TheA-dependence power index of relative mean yield of backward protons was found to bea=0.68±0.12. A drop in the mean yield of backward protons at the four momentum squared over ∼15 (GeV/c)2 (the neutrino energy over ∼50 GeV) was observed.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
NUCLEUS IS AVERAGE NUCLEI OF NUCLEAR EMULSION, <A> ABOUT 80.
Meson production in proton, oxygen and sulphur interactions with uranium targets at 200 GeV/nucleon is studied. We measure the inclusive meson cross-section d σ/dPT2 and its evolution fromp+U to S+U. The cross-section fitted with an exponential gives an inverse slopePT0 of the order of 210 MeV/c. As a function of the neutral transverse energy,PT0 values show a slight rise followed by a plateau. The normalized difference (σ+−σ−)/σ− between positive and negative meson cross-sections is found to increase withET.
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The electroproduction of π0 on the proton was measured from 0 to 2.5 MeV above threshold for virtual-photon 4-momenta of -0.05 and -0.1 (GeV/c)2. The sum of the lowest-order contributing multipoles, a0=‖E0+‖2-εL‖L0+‖2, was determined with a precision an order of magnitude better than previously possible. Our results for a0 are consistent with present calculations. Our extracted value for ‖L0+‖2 at the ‘‘photon point’’ is in agreement with recent predictions.
Joined statistics for two incident electron energy of 300 and 500 MeV.
The B0 B¯ 0 average mixing parameter χ has been extracted from eμ and ee events produced in pp¯ collisions at √s =1.8 TeV. In a sample of 900 eμ events, the like-sign to opposite-sign charge ratio R is measured to be 0.556±0.048(stat)−0.042+0.035(syst). In the absence of mixing, the expected value of R would be 0.23±0.06. The corresponding number for 212 ee events is 0.573±0.116(stat)±0.047(syst) with an expected nonmixing value of 0.24±0.07. The observed excess in R leads to a combined determination of χ=0.176±0.031(stat+syst) ±0.032 (model), where the last uncertainty is due to Monte Carlo modeling.
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