“…However, the situation for σ 01 was not clear in the past. Several experiments reported significant σ 01 values below 600 MeV [28,29,30,31,32], while others found small or even negligible σ 01 contributions for energies up to 750 MeV [33,34,35]. A partial wave analysis of Arndt and Verwest [36] gave no significant σ 01 contribution below 1 GeV while Bystricky et al [37] found small, but non-negligible values in a similar analysis.…”