Threshold production of heavy mesons in the pd → 3HeX0 reaction

The threshold production rates for isoscalar mesons X0 formed through the pd → 3HeX0 reaction are estimated in a two-step model. A virtual pion beam, produced in an NN → dπ reaction on one of the nucleons in the target deuteron, is converted into an X0-meson on the second nucleon via a πN → X0N process. Though too low in magnitude by an overall factor of about 2.4, the model reproduces well the cross section variation deduced from X0 = η, ω, η′, and Φ production data.