Δ0 (1232) production in n+12C collisions at 4.2GeV/c

Abstract

For the first time, the production of [Formula: see text] (1232) resonances has been analyzed in minimum bias [Formula: see text]C collisions at 4.2[Formula: see text]GeV/[Formula: see text]. The value of the mass and width of the [Formula: see text] resonances as well as the fraction of the negative pions coming from [Formula: see text] decay obtained in this work in [Formula: see text]C collisions coincide within the uncertainties with those extracted earlier in [Formula: see text]C collisions at 4.2[Formula: see text]GeV/[Formula: see text] per nucleon. The inclusive cross-section for production of [Formula: see text] (1232) resonances in [Formula: see text]C collisions at 4.2[Formula: see text]GeV/[Formula: see text] is estimated to be [Formula: see text][Formula: see text]mb. Production of [Formula: see text] resonances in [Formula: see text]C collisions at 4.2[Formula: see text]GeV/[Formula: see text] has been investigated separately in regions of fragmentation of the target and projectile. The mass of the [Formula: see text] (1232) proved to be the same within the statistical errors in the target and projectile fragmentation regions. The width of the invariant mass spectrum of [Formula: see text] excited in the projectile region proved to be considerably larger than that in the target fragmentation region, coinciding within statistical errors with that obtained in collisions of free nucleons. The results of the previous experiments, in which production of [Formula: see text] resonances is investigated in the whole phase space (without separating the target and projectile fragmentation regions), can be approximately regarded as the mean values of [Formula: see text] parameters, averaged over those in the target and projectile fragmentation regions.