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

Abstract

We present a theoretical study of the $\gamma \gamma \to \pi \eta$ process from the threshold up to 1.4 GeV in the $\pi \eta$ invariant mass. For the s-wave $a_0(980)$ resonance state we adopt a dispersive formalism using a coupled-channel Omnès representation, while the d-wave $a_2(1320)$ state is described as a Breit-Wigner resonance. An analytic continuation to the $a_0(980)$ pole position allows us to extract its two-photon decay width as ${\Gamma }_{a_0\to \gamma \gamma }=0.27(4)$ keV.

Comments: 10 pages, 7 figures