Reinterpreting several narrow 'resonances' as threshold cusps

The threshold (p) over barp peak in BES data for J/psi --> y (p) over barp may be fitted as a cusp. It arises from the well-known threshold peak in (p) over barp elastic scattering due to annihilation. Several similar examples are discussed. The PS185 data for (p) over barp --> (Lambda) over bar Lambda require an almost identical cusp at the AA threshold. There is likewise a cusp at the EN threshold in K(-)d --> pi(-)(Lambdap). Similar cusps are likely to arise at thresholds for all 2-body de-excitation processes, providing the interaction is attractive; likely examples are Lambda(p) over bar, Sigma(p) over bar, and (K) over bar Lambda. The narrow peak observed by Belle at 3872 MeV in pi(+)pi(-)J/psi may be a J(PC) = 1(++) cusp due to the D (D) over bar* threshold. The narrow Xi*(1862) observed by NA49 may be due to a threshold cusp in Sigma(1385)(K) over bar coupled to Xipi and Sigma(K) over bar. The relation of cusps to known resonances such as f(0) (980) is discussed. (C) 2004 Elsevier B.V. All rights reserved.