The electromagnetic form factors of the neutron in the time-like region have been measured for the first time, from the threshold up to q 2 ⋟ 6 GeV 2 . The neutron magnetic form factor turns out to be larger than the proton one; the angular distribution suggests that for the neutron, at variance with the proton case, electric and magnetic form factors could be different. Further measurements are also reported, concerning the proton form factors and the Σ Σ production, together with the multihadronic cross section and the J / Γ branching ratio into n n .
The uncertainty on the evaluated cross section is given by the quadratic combination of the following terms: the statistical uncertainty on the number of events, the statistical and systematic uncertainty on the luminosity (about 6PCT), the systematic uncertainty on the efficiency evaluation, dominated by the scanning efficiency contribution (about 15PCT). The SQRT(S) values with (C=NOMIN) and (C=SHIFT) correspond to the nominal energy and shifted energy analysis (see text of paper for details).
The uncertainty on the evaluated cross section is given by the quadratic combination of the following terms: the statistical uncertainty on the number of events, the statistical and systematic uncertainty on the luminosity (about 6PCT), the systematic uncertainty on the efficiency evaluation, dominated by the scanning efficiency contribution (about 15PCT). The NEUTRON formfactor value are calculated in two hypotheses: GE = GM and GE = 0.
The uncertainty on the evaluated cross section is given by the quadratic combination of the statistical and systematic uncertainties.
The kinetic energy spectrum and the polarization of the PSI neutron beam produced in the reaction 12C(p,n)X at 0° with 590 MeV polarized protons were investigated. A strong energy dependence of the ne
No description provided.
A polarized proton beam extracted from SATURNE II and the Saclay polarized proton target were used to determine the spin correlation parameter Aoosk and the rescattering observablesKos″ so; Dos″ok, Nos″sn, andNonsk at 1.80 and 2.10 GeV. The beam polarization was oriented perpendicular to the beam direction in the horizontal scattering plane and the target polarization was directed either along the vertical axis or longitudinally. Left-right and up-down asymmetries in the second scattering were measured. A check for the beam optimization with the beam and target polarizations oriented vertically provided other observables, of which results forDonon andKonno at 1.80, 1.85, 2.04, and 2.10 GeV are listed here. The new data at 2.10 GeV suggest a smooth energy dependence of spin triplet scattering amplitudes at fixed angles in the vicinity of this energy.
Spin correlation parameter CSL measured with the beam polarisation measuredalong the +-S direction and the target polarisation along the +-L axis. Additional 4.3 PCT systematic normalisation uncertainty.
Measurement of the rescattering parameter KSS with the beam polarisation inthe +- S direction. Additional 6.7 PCT systematic error.
Measurement of the rescattering parameter KSS with the beam polarisation inthe +- S direction. Additional 6.7 PCT systematic error.
J/ ψ and ψ ′ production cross-sections are measured in pp and pd collisions at 450 GeV/ c at the CERN-SPS. The Drell-Yan cross section for muon pairs in the mass range [4.3–8.0] GeV/ c 2 is also determined in the same experiment.
The measured cross section for J/PSI production for P P and P DEUTERIUM interactions times their branching ratio to MU+ MU- pairs.. The fraction of the systematic error (DSYS) which must be taken into account in comparison of the two targets is 0.06 (0.13) for the P (DEUT) target.
The measured cross section for PSI(3685) production in P P and P DEUTERIUM interactions times their branching ratio to MU+ MU- pairs.. The fraction of the systematic error (DSYS) which must be taken into account in comparison of the two targets is 0.003 (0.006) for the P (DEUT) target.
The measured cross section for Drell Yan production in P P and P DEUTERIUM interactions.. The fraction of the systematic error (DSYS) which must be taken into account in comparison of the two targets is 0.5 (1.2) for the P (DEUT) target.
Inclusive production of the f_0(980), f_2(1270) and \phi(1020) resonances has been studied in a sample of 4.3 million hadronic Z^0 decays from the OPAL experiment at LEP. A coupled channel analysis has been used for the f_0 in simultaneous fits to the resonances in inclusive \pi+\pi- and K+K- mass spectra. Fragmentation functions are reported for the three states. Total inclusive rates are measured to be 0.141 +/- 0.007 +/- 0.011 f_0, 0.155 +/- 0.011 +/- 0.018 f_2, and 0.091 +/- 0.002 +/- 0.003 \phi mesons per hadronic Z^0 decay. The production properties of the f_0, including those in three-jet events, are compared with those of the f_2 and \phi, and with the Lund string model of hadron production. All measurements are consistent with the hypothesis that the f_0 is a conventional qq(bar) scalar meson.
Total inclusive production rates.
Fragmentation functions. Additional systematic errors of 7.6 PCT for F0, 11.6 PCT for F2 and 3.5 PCT for PHI. The uncorrelated systematic errors for F0 and F2 are negligible in comparison to the other errors.
A study has been performed of the reaction pbar p -> 4K using in-flight antiprotons from 1.1 to 2.0 GeV/c incident momentum interacting with a hydrogen jet target. The reaction is dominated by the production of a pair of phi mesons. The pbar p -> phi phi cross section rises sharply above threshold and then falls continuously as a function of increasing antiproton momentum. The overall magnitude of the cross section exceeds expectations from a simple application of the OZI rule by two orders of magnitude. In a fine scan around the xi/f_J(2230) resonance, no structure is observed. A limit is set for the double branching ratio B(xi -> pbar p) * B(xi -> phi phi) < 6e-5 for a spin 2 resonance of M = 2.235 GeV and Width = 15 MeV.
No description provided.
No description provided.
Fine scan of the PHI PHI cross section.
This paper reports on the charged K / π production ratios and on the shape of the p T distributions of π fluxes measured by the SPY/NA56 experiment for 450 GeV/c proton interactions on beryllium targets. The present data cover a secondary momentum range from 7 GeV/c to 135 GeV/c in the forward direction and with p T values up to 600 MeV/c. An experimental accuracy of about 3% has been achieved. These results will reduce the uncertainty on the estimation of the ν e component of neutrino beams.
No description provided.
No description provided.
Additional systematic error of 1.3 PCT.
The ratio of the exclusive production cross sections for φ and ω mesons has been measured in pp reactions at Tbeam=2.85GeV. The observed φ/ω ratio is (3.7±0.7−0.9+1.2)×10−3. After phase space corrections, this ratio is about a factor of 10 enhanced relative to naive predictions based upon the Okubo-Zweig-Iizuka rule, in comparison to an enhancement by a factor of ∼3 previously observed at higher energies. The modest increase of this enhancement near the production threshold is compared to the much larger increase of the φ/ω ratio observed in specific channels of p¯p annihilation experiments.
No description provided.
The double differential cross section for pn→pp(1S0)π− at three beam energies has been extracted from the quasifree process pd→pppπ−. A comparison is carried out with single differential cross section measurements for 3He(π−,pn)n, where the pion is thought to be absorbed onto a pp(1S0) “diproton” state. A significant difference is observed in the shape of the angular distribution between the production and absorption data. This difference is ascribed to the effects of the 3He nuclear environment characterizing the absorption process; however, an adequate theoretical explanation is not available.
Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.
Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.
Only statistical errors are given in the table. Final P P system is in 1S0 ((2S+1) L J) state.
The 1H(e,e′K+)Λ reaction was studied as a function of the squared four-momentum transfer, Q2, and the virtual photon polarization, ɛ. For each of four Q2 settings, 0.52, 0.75, 1.00, and 2.00 (GeV/c)2, the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The Q2 dependence of the σL/σT ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations.
The systematic and statistical errors are added in quadrature. OMEGA is the solid angle of K+ in CMS.
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