Is there an eta(3) He quasi-bound state?

The observed variation of the total cross section for the dp -> He-3 eta reaction near threshold means that the magnitude of the s-wave amplitude falls very rapidly with the eta centre-of-mass momentum. It is shown here that recent measurements of the momentum dependence of the angular distribution imply a strong variation also in the phase of this amplitude. Such a behaviour is that expected from a quasi-bound or virtual eta He-3 state. The interpretation can be investigated further through measurements of the deuteron or proton analysing powers and/or spin-correlations. (C) 2007 Elsevier B.V. All rights reserved.