Theoretical analysis of the $\gamma {\gamma }^{(\ast )}\to {\pi }^0\eta$ process

Abstract

The theoretical analysis of the $\gamma \gamma \to {\pi }^0\eta$ process is presented within the energy range up to 1.4 GeV. The $S$-wave resonance $a_0(980)$ is described involving the coupled channel dispersive framework and the $D$-wave $a_2(1320)$ is approximated as a Breit-Wigner resonance. For the $a_0(980)$ the pole is found on the IV Riemann sheet resulting in a two-photon decay width of ${\Gamma }_{a_0\to \gamma \gamma }=0.27(4)$ keV. The first dispersive prediction is provided for the single-virtual $\gamma {\gamma }^{\ast }(Q^2)\to {\pi }^0\eta$ process in the spacelike region up to $Q^2=1$ GeV${}^2$.

4 pages, 1 figure, proceedings of the MESON2018 (15${}^{\text{th}}$ International Workshop on Meson Physics, KRAKÓW, POLAND, 7th - 12th June 2018)