Search for narrow peaks in inclusive π0 spectra from p annihilation at rest

The antinucleon–nucleon interaction at low energy: Annihilation dynamics

“…Values in a gas target (ρ STP ), both with and without an atomic L X-ray trigger, have been obtained As can be seen from Table 17, there are widely differing measurements for the π 0 π 0 annihilation frequency in liquid targets, particularly so for the Crystal Barrel [167,210] and Obelix [158] experiments. Whilst the Obelix measurement agrees with some earlier data [106,291] where only 2 or 3 photons were observed, it should be noted that Obelix, Crystal Barrel and the work of Devons et al [89] are the only experiments to measure all 4 photons and to reconstruct 2π 0 events fully. The fact that the π + π − annihilation frequencies obtained by the Crystal Barrel and Obelix experiments are in good agreement, suggests that the origin of the problem lies in the determination of the reconstruction efficiency for detecting π 0 π 0 events.…”

“…Whilst the recent Obelix [158] value for AF(π 0 η, liq) is supported by the measurement of Adiels et al [293], it is not in agreement with other early results [106,263] which show particularly large [215]C E N fluctuations in value. This may be compared to the situation for thepp → π 0 π 0 frequency discussed in Sec.…”

“…Whilst the recent Obelix [158] value for AF(π 0 η, liq) is supported by the measurement of Adiels et al [293], it is not in agreement with other early results [106,263] which show particularly large This may be compared to the situation for the pp → π 0 π 0 frequency discussed in Sec. 6.4.3 above which has been used by the Obelix collaboration [158] as support for their low value of BR(π 0 π liq.).…”

“…The initial aim was to find narrow multiquark or quasi-nuclear bound states [102][103][104][105]. Later, frequencies for annihilation into two narrow mesons were determined with both H 2 [106,107] and D 2 [108] targets.…”