Measurement of thep¯pCharge-Exchange Cross Section from 0.119 to 1.046 GeV/c

Antiproton-proton partial-wave analysis below 925 MeV/c

“…For the experiment of Ref. [99] data points at the lowest momenta are rejected since they are in conflict with more recent measurements done at LEAR by the PS173 group [103]. Our PWA clearly favors this last experiment.…”

“…Integrated charge-exchange cross sections, on the other hand, are included in the database. In two experiments [108,99] this observable was measured over a large momentum region. For the experiment of Ref.…”

Search for theSMeson

“…8 and d(7{pp-*pp)/d$l at 180°, 9 we have remeasured the pp and pd total cross sections in an experiment specifically designed for the study of narrow resonances at low p momenta. The experiment took place in beam LESB I at the Brookhaven alternating-gradient synchroton (AGS) and was performed in the same manner as that of Carroll et al, 1 namely, by the transmission technique whereby the total cross section is obtained by extrapolation of the cross sections measured by a series of counters of diminishing size to one subtending zero solid angle.…”

“…The shorter target also improved our cm* energy resolution so that at the reported S meson (~ 500 MeV/c), the rms value was ±1.5 MeV. 8 Whereas the beam used in Ref. 1 was defined by wire chambers, we used a counter telescope whose final element was a thin (1.6-mm) counter placed directly upstream of the target in order to ensure that all particles defined as antiprotons did indeed traverse the target.…”

Comprehensive evidence for a narrow

“…A ne-step scan of this region has been done in four experiments only: two of them, [31,32], studying the total and charged annihilation pp cross sections; and two others studying the backward elastic cross section [33], and the charge exchange ( pp ! nn) cross section, [34]. No signal of the 2.02 GeV/c 2 state was found; the most accurate restrictions result from the charge exchange experiment [34] (see below).…”