Angular correlations in γγ→ρ0ρ0 near threshold

Angular correlations in γγ→ρ0ρ0 near threshold

We present an analysis of ρ0ρ0 production by two photons in the ρ0ρ0 invariant mass range from 1.2 to 2.0 GeV. From a study of the angular correlations in the process γγ→ρ0ρ0→π- π+π- we exclude a dominant contribution from JP=0- or 2- states. The data indicate sizeable contributions from JP=0+ for f...

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Bibliographic Details
Main Authors: Althoff, M, Braunschweig, W, Gather, K, Kirschfink, F, Lübelsmeyer, K, Martyn, H, Peise, G, Rimkus, J, Sander, H, Schmitz, D, Siebke, H, Trines, D, Wallraff, W, Boerner, H, Fischer, H, Hartmann, H, Hilger, E, Hillen, W, Knop, G, Köpke, L, Kolanoski, H, Wedemeyer, R, Wermes, N, Wollstadt, M, Burkhardt, H
Format: Journal article
Language:English
Published: Springer-Verlag 1982
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Summary:We present an analysis of ρ0ρ0 production by two photons in the ρ0ρ0 invariant mass range from 1.2 to 2.0 GeV. From a study of the angular correlations in the process γγ→ρ0ρ0→π- π+π- we exclude a dominant contribution from JP=0- or 2- states. The data indicate sizeable contributions from JP=0+ for four pion masses M4π<1.7 GeV and from JP=2+ for M4π>1.7 GeV. The data are also well described by a model with isotropic production and uncorrelated isotropic decay of the ρ0,s. The cross section stays high below the nominal ρ0ρ0 threshold, i.e. M4π<1.5 GeV. The matrix element for ρ0ρ0 production is found to decrease steeply with increasing M4π. Upper limits for the couplings of the ι(1440) and Θ(1640) to γγ and ρ0ρ0 are given:Γ(ι→γγ)·B(ι→ρ 0ρ0)<1.0 keV and Γ(Θ→γγ) © 1982 Springer-Verlag.

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