Can the gamma-gamma processes reveal the nature of the sigma ?

Gerard Mennessier (1) , P. Minkowski , Stéphan Narison (1) , W. Ochs

1 LPTA - Laboratoire de Physique Théorique et Astroparticules

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.

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]

Gerard Mennessier, P. Minkowski, Stéphan Narison, W. Ochs. Can the gamma-gamma processes reveal the nature of the sigma ?. HEPMAD07, Sep 2007, Antananarivo, Madagascar. 6pp. ⟨hal-00377710⟩