Search for narrow baryonium states near the NN threshold

The reactions p p →π − X and p d → pX earch for narrow baryonium states in the mass region between 1.6 and 2.0 GeV/c2. No such state has been observed. In the first reaction the upper limit for the production of narrow baryonium states is 8μb/sr for a 3 standard deviation signal with 4 MeV/c2 width. In the second reaction this limit is 10 μb/sr. The second reaction is rather insensitive for observation of baryonium states as it is dominated by quasi-free contributions.