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.
The complete charge distribution of products from Au nuclei fragmenting in nuclear emulsion at 10.7A GeV has been measured. Multiplicities of produced particles and particles associated with the targe
No description provided.
No description provided.
The reaction p ̄ p→K + K − π 0 was analysed for antiproton annihilations at rest at three hydrogen target densities. A strong dependence of the p ̄ p→φπ 0 yield on the quantum numbers of the initial state is observed. The branching ratio of the φπ 0 channel from the 3 S 1 initial state is more than 15 times larger than the one from the 1 P 1 state. A large apparent violation of the OZI rule for tensor meson production from p ̄ p -annihilations from the P -waves (1 ++ +2 ++ ) is observed: R exp ( f ′ 2 π 0 / f 2 π 0 )=(149±20)·10 −3 , significantly exceeding the OZI-rule prediction R =16·10 −3 .
Three densities (LH2, NTP, and LP) of the hydrogen target.
S- and P-wave in the initial PBAR P system.
S- and P-wave in the initial PBAR P system.
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.
Using linearly polarized tagged photons from coherent bremsstrahlung, differential cross sections and beam asymmetries for Compton scattering by 4 He have been measured at MAMI in the energy interval between 150 MeV and 500 MeV for scattering angles of θ γ lab =37°, 93° and 137°, thus largely increasing the available data base. Improved calculations in terms of the Δ -hole model completely fail to describe the data at large scattering angles. The same proved to be true for a schematic model, even after taking into account properties of nuclear photo-absorption in very detail.
Axis error includes +- 0.0/0.0 contribution.
The reaction pp → K + Λp was measured exclusively at the cooler synchrotron COSY at beam momenta of p Beam = 2.50 GeV/c and p Beam = 2.75 GeV/c using the TOF detector. Angular and momentum distributions were obtained for the full phase space of the reaction products. Total cross sections were extracted to be (2.7 ± 0.3) μ b and (12.0 ± 0.4) μ b, respectively. The polarization of the Λ -hyperon was determined as a function of its transversal momentum and was found to be negative for transverse momentum transfers of p T ≥ 0.3 GeV/c. The results together with existing data are compared with phenomenological parametrizations and model calculations on the basis of meson exchange.
Axis error includes +- 10/10 contribution (Overall normalization error).
The analyzing power,$A_{oono}$, and the polarization transfer observables$K_{onno}$,$K_{os''so}$
Position 'A' (see text for explanation).
Position 'A' (see text for explanation).
Position 'A' (see text for explanation).
The total cross section for the π−p→π−π+n reaction has been measured at incident pion kinetic energies of 200, 190, 184, and 180 MeV. In addition, the π+p→π+π+n reaction was measured at 200 and 184 MeV. A fit of the cross sections by heavy baryon chiral perturbation theory yields values of 8.5±0.6(mπ−3) and 2.5±0.1(mπ−3) for the reaction matrix elements A10 and A32, which correspond to values for the s-wave isospin-0 and isospin-2 π−π scattering lengths of a0=0.23±0.08(mπ−1) and a2=−0.031±0.008(mπ−1), respectively.
No description provided.
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.
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.
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