On the Coalescence Production of Broad Resonances

The situation is considered when a particle, produced in the initial interaction of a projectile with one of nucleons, then coalesces with a residual nuclear system forming a nearthreshold resonance with the width of the order of several MeV. It is shown that a sharp variation of the amplitude, associated with triangle mechanism, can appreciably influence visible parameters (the width and position) of final resonance system. The case of _Σ ^4{He} production is described in detail.