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We present a new high-statistics measurement of the cross section for the process e+e~e+e m. +m at a center-of-mass energy of 29 GeV for invariant pion-pair masses M(m+m ) between 350 MeV/c' and 1.6 GeV/c2. We observe the f~( 1270) and measure its radiative width to be 3. 15+0.0420. 39 keV. We also observe an enhancement in the~+~spectrum near 1 GeV. General agreement is found with unitarized models of the yy~m m. reaction that include finalstate interactions.

W e report a measurement o f the diffraction dissociation differential cross section d 2 u s~/ d M 2 d t for ?Sp + pX at f i = 546 and 1800 G e V , M 2 / s < 0.2 and 0 < -t < 0.4 G~v~. Our results are compared t o theoretical predictions and t o extrapolations from experimental results at lower energies. PACS number(s): 13.85.Hd, 12.40.Nn

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