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$γγ\to π^0 π^0$ as a test for the existence of a light $σ$ meson

J. L. Lucio·G. Moreno·M. Napsuciale·J. J. Toscano
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Abstract

We work out predictions of the Linear Sigma Model for the $γγ\toπ^0 π^0$ cross section. We consider the sigma width, which is introduced in a consistent way with chiral Ward identities. The results of Chiral Perturbation Theory are recovered in the $m_σ\to \infty$ limit. A fit to existing experimental results is consistent with a light and broad $σ$ meson.

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J. L. Lucio, G. Moreno, M. Napsuciale, J. J. Toscano. 1999-04-06. $γγ\to π^0 π^0$ as a test for the existence of a light $σ$ meson. https://arxiv.org/abs/hep-ph/9810299

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