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.