A narrow baryon resonance is observed in invariant mass of the K 0 S p system formed in neutrino and antineutrino collisions with nuclei. The mass of the resonance is estimated as 1533 ± 5 MeV. The observed width is less than 20 MeV, and is compatible with being entirely due to experimental resolution. The statistical significance of the signal is near 6.7 standard deviations. The analysis is based on the data obtained in past neutrino experiments with big bubble chambers: WA21, WA25, WA59, E180, and E632.

High precision measurements of the differential cross sections for π0 photoproduction at forward angles for two nuclei, 12C and 208Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the π0→γγ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0→γγ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0→γγ)=7.82±0.14(stat)±0.17(syst)  eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

We have continued our investigation of the charge-exchange reaction K + Xe → K 0 pXe ′ in the bubble chamber DIANA. In agreement with our previous results based on part of the present statistics, formation of a narrow pK 0 resonance with mass of 1537 ± 2 MeV/c 2 is observed in the elementary transition K + n → K 0 p on a neutron bound in the Xenon nucleus. Visible width of the peak is consistent with being entirely due to instrumental resolution and allows to place an upper limit on its intrinsic width: Γ < 9 MeV/c 2 . A more precise estimate of the resonance intrinsic width, Γ = 0.36 ± 0.11 MeV/c 2 , is obtained from the ratio between the numbers of resonant and non-resonant charge-exchange events. The signal is observed in a restricted interval of incident K + momentum, that is consistent with smearing of a

The data on the charge-exchange reaction K + Xe → K 0 pXe ′ , obtained with the bubble chamber DIANA, are reanalyzed using increased statistics and updated

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