Observation of a Dip Due toI=0t-Channel Exchange in the ReactionπN→A2Nat 4.5 and 6 GeV/c

Abstract

In the reaction ${\pi }^{-}p\to {A_2}^{-}p$, we observe a dip in the differential cross section at $t\approx 1.2$ Ge${\mathrm{V}}^2$. Analysis in terms of $t$-channel contributions from isospin-0 and -1, natural- and unnatural-parity exchanges suggest that the dip is mainly due to natural-$\stackrel{\mathrm{`}}{\mathrm{p}}$arity, $I=0\mathrm{}$ exchange.