Evidence against broad dibaryons

Spin-correlation parameters $A_{\mathrm{LL}}$, $A_{\mathrm{SL}}$, $A_{\mathrm{NL}}$, $A_{N0}$, $A_{S0}$, $A_{L0}$, and $A_{0L}$ have been measured for the reaction pp→np${\pi }^{+}$ at 492, 576, 643, 729, and 796 MeV. An isobar analysis determines magnitudes and phases of partial waves up to NN ${}_{}{}^3{}_{}{}^{}F_3^{}{}_{}{}^{}$. For the amplitude NN${(}^1$ $D_2$)→NΔ${(}^5$ $S_2$), the phase shows a strong threshold enhancement in the NΔ channel, dropping from 44.4°±4.4° at 492 MeV to 11.9°±1.9° at 796 MeV. Other phases show little activity. Broad dibaryons are conclusively ruled out in ${}_{}{}^1{}_{}{}^{}\mathrm{D}_2^{}{}_{}{}^{}$, ${}_{}{}^3{}_{}{}^{}\mathrm{F}_3^{}{}_{}{}^{}$, and ${}_{}{}^3{}_{}{}^{}\mathrm{P}_2^{}{}_{}{}^{}$ in this energy range.