Ref HAL: hal-00377710_v1
Ref Arxiv: 0707.4511
Ref. & Cit.: NASA ADS
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Résumé:

We reanalyse the gamma-gamma scattering data and conclude that in the massregion below 1 GeV the cross section for gamma-gamma to pi^0-pi^0 can belargely explained by the one pion exchange process with pi-pi rescattering. Theradiative width of the sigma is estimated and a model dependent separation intocontributions from direct gamma-gamma decay and decay through rescattering isobtained. We confront these findings with QCD spectral sum rule (QSSR)predictions and conclude that the sigma can have a large gluonium component inits wave function.