Analytical dispersive construction of $\eta \to 3\pi$ amplitude: First order in isospin breaking

Karol Kampf, Marc Knecht, Jiří Novotný +1

Because of their small electromagnetic corrections, the isospin-breaking decays $\eta \to 3\pi$ seem to be good candidates for extracting isospin-breaking parameters $(m_d-m_u)$. This ta…