Peripheral Production of Resonances

Abstract

We review the peripheral cross‐sections of resonances that cannot be produced by π‐exchange. Explicitly we consider the four nonets of mesons n the L = 1 quark classification, JP = 0+ πN(980); 1+, e.g., A1, B; 2+, e.g., A2. We detail the constraints of SU3, exchange degeneracy, factorization, pole extrapolation, Watson's theorem and duality as they have been gleaned from long and painful study of well‐loved reactions. The controversial nature of the 0+ and 1+ nonets is related to a surprising suppression of their cross‐sections (which are around 10 μb at 5 GeV/c) in non‐diffractive processes. This is explained by a generalized vector meson photon analogy model recently proposed by Kislinger. We predict all differential cross‐sections for these L = 1 quark states and show that these mesons are best studied in hypercharge exchange reactions, e.g., π−p ⇒ Q0Λ and K−n ⇒ A1−Λ.An explanation, using final state interaction theory, of the large background under the Q and A1 observed in diffractive processes, sugge...