Diffractive dissociation and N∗ production in π−n → π−π−p at 15 GeV/c

Diffractive dissociation of neutrons and N∗ production are studied in the reaction π−n → π−π−p at 15 GeV/c. The reaction is dominated by a broad, low-mass diffractive enhancement in the pπ− mass. Evidence is presented for the production of at least one N∗ resonance in the mass region 1.4–1.8 GeV. Comparison with ISR data suggest that this N∗ resonance is produced by pomeron exchange. The N∗ production occurs predominantly at t′ > 0.1 GeV2 which suggests a different coupling from the usual diffractive reactions. The non-resonant diffractive background is compared with a double-Regge model and the statistical dissociation model.