Understanding COMPASS data on $\pi^-+ p\rightarrow \eta^{(\prime)}+\pi^-+ p$ in the double-Regge region

Resonance production is known to be dominant at low $\eta^{(\prime)}\pi^-$ mass in the diffractive reaction $\pi^-+p\rightarrow\eta^{(\prime)}\pi^-+p$, while production via a double-Regge exchange process is contributing as a considerable background. At high $\eta^{(\prime)}\pi^-$ mass, double-Regge exchange becomes the dominant process. We study the double-Regge exchange at high $\eta^{(\prime)}\pi^-$ mass for the first time in an event based analysis, using the full recorded data set from COMPASS, which is the largest data set to date in this final state. We show that the double-Regge exchange model describes the data very well. Additionally, we make the observation that $\mathbb{P}$ exchange is not solely dominating at the proton proton vertex.