π ° photoproduction cross sections on proton have been measured at π° c.m. angles between 115° and 180° and between 700 MeV and 1150 MeV photon energies by detecting only the recoil proton. Our results show clearly a peak at 135° around 1000 MeV energies as predicted by Walker's partial wave analysis.
No description provided.
No description provided.
No description provided.
The reaction e + e − → ω o has been measured by detecting the charged pions of the π + π − π o decay mode of the ω o. A partial decay width of ω o in e + e − : Γ e + e − =0.94±0.18 keV is deduced from this result.
FITTED, BACKGROUND SUBTRACTED, PEAK OMEGA CROSS SECTION, CORRECTED FOR UNOBSERVED DECAYS, IS 1.82 +- 0.34 MUB. TABULATED ASSUMING CENTRAL ENERGY IS 782.6 MEV. VACUUM POLARIZATION AND RADIATIVE CORRECTIONS APPLIED.
The electromagnetic form factor of the pion has been determined in the ϱ o resonance region by measuring the absolute cross section of the reaction e + e − → π + π − with the Orsay storage ring. More than 800 pion pairs have been detected. The excitation curve has been fitted with a Breit-Wigner formula which leads to the following values: σ peak = (1.69 ± 0.21) 10 −30 cm 2 ; m ϱ = (770 ± 4) MeV ; Γ ϱ = (111 ± 6) MeV . The partial width of the ϱ o going into e + e − thus obtained is: Γ ϱ → e + e − =(7.36±0.7) keV .
No description provided.
The angular distributions of K + p and π + p backward elastic scattering have been measured at 5.2 and 6.9 GeV/ c . Backward π - p and K - p elastic scattering were studied at 6.9 GeV/ c . Backward peaks are observed in K + p scattering with an energy dependence of the form s −4 .
No description provided.
Inelastic electron proton scattering has been measured by detecting the scattered electron, thus obtaining the total absorption cross section for virtual photons. Two complete spectra from threshold to a pion nucleon mass of W = 2 GeV were taken at θ e = 48.3° and fixed primary energies of 3.963 GeV and 5.159 GeV, respectively, corresponding to a momentum transfer at the first resonance of q 2 = 3.98 (GeV/ c ) 2 and q 2 = 5.84 (GeV/ c ) 2 . In addition, a measurement at θ e = 47.9° and at a primary energy of 3.306 GeV in the region of the first resonance is reported.
No description provided.
We have studied nonstrange p¯−p interactions observed in 7000 pictures of the 80-in. Brookhaven National Laboratory hydrogen bubble chamber exposed to an antiproton beam with a momentum of 6.94 BeVc. The total cross section was measured to be 58.7±2.8 mb, and the elastic interaction cross section 14.2±1.2 mb. The elastic differential cross section for four-momentum transfers (−t)≤0.3 (BeVc)2 is well described by the exponential form dσeldt=(dσdt)t=0ebt, where b=13.1±1.1 (BeVc)−2. The single-pion production cross section is 4.0±0.9 mb. This channel proceeds 70% through resonance formation. N*(1238) isobar and anti-isobar formation dominates pion production in four- and six-pronged events; the double-isobar formation cross section in the final state pπ+p¯π− is 1.35±0.2 mb. Isobar production was observed to be consistent with the predictions of a dominant one-particle-exchange process. The pion-annihilation process, which has a cross section of 25±5 mb, shows substantial pion resonance formation.
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The reaction e+d→e′+n+p was studied at electron scattering angles θ ⩽ 35° for four-momentum transfers of 0.39, 0.565 and 0.78 (GeV/ c ) 2 . By recording electron-neutron and electron-proton coincidences, the ratio of the electron scattering cross sections on quasi-free neutrons and protons was determined. An estimate of the binding effects, based on a Chew-Low-extrapolation, was made. Values for the neutron form factors were derived.
Axis error includes +- 0.0/0.0 contribution (Due to the different effective solid angles for neutron and proton detection in the counters).
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Total and differenial cross sections of the reaction γ +n→p+ π − have been determined for photon-energies between 0.2 and 2.0 GGeV. Below 500 MeV the differential cross sections are compared with theoretical predictions derived from fixed-momentum-transfer dispersion relations.
Axis error includes +- 0.0/0.0 contribution (5 TO 8////).
Axis error includes +- 0.0/0.0 contribution (5 TO 8////).
Axis error includes +- 0.0/0.0 contribution (5 TO 8////).
We have measured the antiproton-proton elastic differential cross section in the center-of-mass angular range cosθ=−0.985 to +0.40 at six momenta between 1.6 and 2.2 GeV/c in a bubble-chamber experiment. We use the data to look for evidence of direct-channel boson resonances.
No description provided.
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