Chiral Dynamics Predictions for $\eta'\to\eta\pi\pi$

Understand

We study the decay $\eta'\to\eta\pi\pi$ in two different chiral invariant approaches: Large-$N_c$ Chiral Perturbation Theory (ChPT) and Large-$N_c$ Resonance Chiral Theory (RChT).

• We analyze the Dalitz plot and the invariant mass spectra.
• We also compare the relevance of the isoscalar and isovector channels in these approaches.
• While the predictions of Large-$N_c$ ChPT at next-to-leading order slightly disagree with the measured decay width (showing the need for final state interactions and higher order local contributions), a reasonable agreement is obtained for the case of RChT.