The e + e − → p p cross section has been measured in the energy interval (1975 ⩽ 2 E ⩽ 2250) MeV for |cos θ | < 0.7. The measurement is based on ∼ 100 events, thus improving by a factor 3 on the previous existing statistics in this energy interval. The form factor | G | 2 is given as a function of energy under the assumption | G E | = | G M |. We also give the first measurement of the differential cross section, averaged over the energy interval, and estimate the ratio G M |/| G E | from it.
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We have observed an azimuthal asymmetry in inclusive hadron production by e+e− annihilation at the center-of-mass energy s=7.4 GeV. The asymmetry is caused by the polarization of the circulating beams in the storage ring and allows separate determination of the transverse and longitudinal structure functions. We find that transverse production dominates for x>0.2 where x is the scaling variable 2ps.
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The reactions e+e−→e+e− and e+e−→μ+μ− have been measured at center-of-mass energies 3.0, 3.8, and 4.8 GeV and production angles of 50°<θ<130° over all azimuthal angles. Agreement with quantum electrodynamics is excellent. New limits for cutoff parameters in quantum-electrodynamic-breakdown models are given.
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