Discussion of the eta to pi^0 gamma gamma decay within a chiral unitary approach
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# Discussion of the eta to pi^0 gamma gamma decay within a chiral unitary approach

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 Oset Báguena, Eulogio Perfil; Peláez Sagredo, José Ramón; Roca Zamora, Luis Aquest document és un/a article, creat/da en: 2006 We improve the calculations of the $\eta \to \pi^0 \gamma \gamma$ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the $a_0(980)$ resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition we ensure the consistency of the approach with other processes. First, by using vector meson dominance couplings normalized to agree with radiative vector meson decays. And, second, by checking the consistency of the calculations with the related $\gamma \gamma \to \pi^0 \eta$ reaction. We find an $\eta \to \pi^0 \gamma \gamma$ decay width of $0.47\pm 0.10$ eV, in clear disagreement with published data but in remarkable agreement with the most recent measurement. Oset Báguena, Eulogio Peláez Sagredo, José Ramón Roca Zamora, Luis 2006 Discussion of the eta to pi^0 gamma gamma decay within a chiral unitary approach Acta Physica Slovaca 56 3 327 333