Nuclear PhysicsB133 (1978) 285 296 © North-ttolland Publishing Company EVIDENCE FOR EXCHANGE DEGENERACY REANALYSED R.G. ROBERTS Rutherford Laboratory, Chilton, Didcot, Oxon., UK R.V. GAVA1 and D.P. ROY Tata Institute of Fundamental Research, Homi Bhabha Road, Bombay 5, India Received 25 August 19+77 We present a detailed analysis of Kp and 7rp total cross sections with a view to investi- gating the validity of strong exchange degeneracy which has recently been questioned. Kp CEX data is used to extract the p-A 2 exchange. This contribution is important in deter- mining the exact behaviour of the pomeron at lower energies which in turn crucially affects the f-exchange contribution. Assuming ideal mixing for the f, we conclude that the f-co residues satisfy strong exchange degeneracy, a result which can be interpreted as an impor- tant consistency check for Harari-Freund duality. 1. Introduction Strong exchange degeneracy (EXD) is usually interpreted in terms of Harari-Freund duality, i.e. the equivalence between the resonance and Regge contributions to the imaginary part of an amplitude. From this follows; (i) that the net reggeon contribu- tion to the exotic cross sections like KN or NN vanish, and (ii) if we make reasonable assumptions like SU(3) symmetry and factorisation for the couplings, the net reggeon contributions for rr-p and 7r+p are equal to those for K-p and K-n respectively. It is well known that for Plab = 5 -+ 25 GeV/c, the experimental KN and NN total cross sections are fairly flat with energy and the reggeon contributions to rr-p(Tr+p) and K-p(K-n) total cross sections, extracted by assuming a flat pomeron contribution are, indeed, equal. That is, assuming a pomeron with constant energy dependence, the data below 25 GeV/c on total cross sections are in agreement with strong EXD predictions [1 ]. Indeed, this has been considered the strongest experimental evidence in support of duality. However, the discovery of rising total cross sections at higher energies has cast serious doubt on this simple picture. The simplest models for the pomeron, involving a monotonic energy dependence, would suggest that the pomeron contribution rises over the lower-energy (5 -+ 25 GeV/c) range as well. To reconcile this with a flat KN or NN total cross section requires a net positive reggeon contribution (/3f >/3c~) which