A meson-theoretical explanation of the f 0 (980)-production puzzle in the reaction π− p → π0π0 n

A meson-theoretical model for the reaction π^? p → π⁰π⁰ n for large π^? momenta is developed which treats the final-state interaction between the two produced pions microscopically. For small momentum transfers, the squares of the S-wave amplitudes of the produced two-pion system show a dip for invariant twopion masses in the vicinity of the f ₀(980) meson, while for momentum transfers ?t>0.2(GeV/c)², the f ₀(980) meson appears as a bump. The model provides a microscopic explanation of the long-standing puzzle seen by both the GAMS and the BNL experimental collaborations.