On sequential single-pion production in double-pionic fusion

Recently a two-step process has been proposed for the double-pionic fusion to deuterium pn (I = 0) → dπ⁺π^-. Its calculation is solely based on total cross section data for the two sequential single-pion production steps pn (I = 0) → ppπ^- followed by pp → dπ⁺. Though this sequential process was aimed to explain the dibaryon resonance d^⁎ (2380) peak in double-pionic fusion, we demonstrate that this is not the case. It rather fits to a possible broad bump at 2.31 GeV in the energy dependence of the pn → dπ⁰π⁰ reaction, which was recently interpreted as a consequence of dibaryonic excitations in isoscalar single-pion production.