New data on Δ++-baryon production in pd annihilation at rest

New experimental results on pd annihilation at rest into pions plus a high momentum proton in the final state are discussed. The data sample was collected using the OBELIX spectrometer at the LEAR facility (CERN). The annihilation probabilities, or more precisely the yields (Y) via channels pd → 2π−π+π0p and pd → 3π−2π+π0p with proton momenta p > 400 MeV/c have been measured for the first time: Y = (93.2 ± 1.6) × 10−4 and Y = (52.2 ± 1.4) × 10−4, respectively. The signal in the invariant mass distribution of the pπ+ system in the region of the well-known Δ++(1232)-isobar is clearly seen in reactions pd → 2π−π+p, pd → 2π−π+π0p, pd → 3π−2π+p and pd → 3π−2π+π0p. The upper limit on reaction p (Δ−Δ++) → 2π−π+p in the pd annihilation at rest, which could be interpreted as a manifestation of the ΔΔ component of the deuteron, was found to be Y ≤ 6.5 × 10−5 with a 90% confidence level.