Observation of meson central production in baryon exchange processes

First observation of strong OZI rule violation in πN interactions

“…As a rule, such particles were not detected by the WA56 tracking apparatus. So, from the methodological point of view, the problem of identication of the processes (3) and (5) with the slow pion is similar to that of the work [12] where the study of the central production of the 0 , f 2 ; 0 3 mesons in the baryon exchange reaction…”

“…The layout of the spectrometer as used in the WA56 experiment is described in detail in [11,12]. We recall here that the main trigger requirement was the detection of a fast forward proton with momentum greater than 10 (7) GeV/c in + p ( p) reactions at the incident momentum 20 (12) GeV/c.…”

Comprehensive evidence for a narrow

“…The layout of the spectrometer as used in the WA56 experiment ( Figure 2) is described in detail in [1,7]. We recall here that the main trigger requirement was the detection of a fast forward proton with momentum greater than 10 (7) GeV/c in + p ( p) reactions at an incident momentum of 20 (12) GeV/c.…”

“…The data samples were composed of 3-prong events of ++ topology (with one charged track undetected by the spectrometer), 4-prong charge-balanced events with a missing neutral(s), and 5-prong events o f + + + + topology, in the case of reaction (3). Then, following the same method as used in [7] for the study of reaction (6), a 1-C t procedure was implemented to reconstruct the 4-momenta of missed pions from reactions (1)(2)(3)(4)(5). First, the missing mass squared (M M 2 ), was calculated with appropriate mass hypotheses for the detected particles, where clear signals of lost + s , 0 s and s were seen ( Figure 3).…”

“…at 20 GeV/c (the corresponding diagram is shown in Figure 1b), based on the WA56 data [7], where an experimental approach similar to that which will be presented in this work was used. In the analysis of reaction (6) it was shown that, in baryon exchange induced reactions, the central region is particularly suitable for meson spectroscopy studies, providing a good signal/background ratio.…”