Two-Photon
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Total hadronic cross-section of photon photon interactions at LEP.

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Alexander, G. ; et al.
Eur.Phys.J.C 14 (2000) 199-212, 2000.
Inspire Record 502548 DOI 10.17182/hepdata.49107

The total hadronic cross-section sigma_gg(W) for the interaction of real photons, gg->hadrons, is measured for gg centre-of-mass energies 10 e+e-g*g* -> e+e- hardrons, using a luminosity function for the photon flux together with form factors for extrapolating to real photons (Q^2=0 GeV^2). The data were taken with the OPAL detector at LEP at e+e- centre-of-mass energies 161, 172 and 183 GeV. The cross-section sigma_gg(W) is compared with Regge factorisation and with the energy dependence observed in gp and pp interactions. The data are also compared to models which predict a faster rise of sigma_gg(W) compared to gp and pp interactions due to additional hard gg interactions not present in hadronic collisions.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Measurement of Lepton and Pion Pair Production in Photon - Photon Collisions at Dci

Courau, A. ; Falvard, A. ; Haissinski, J. ; et al.
Phys.Lett.B 96 (1980) 402-406, 1980.
Inspire Record 153776 DOI 10.17182/hepdata.49087

We report a photon-photon experiment performed at the Orsay storage rings. 300e + e − , μ + μ − and π + π − pairs produced with low invariant masses have been observed. For each event, one or both protons have been tagged at a very small angle. The γγ→μ + μ − and γγ→π + π − cross-sections have been measured near threshold, the γγ→e + e − process being used as a normalization. The observed invariant mass distribution is compared to theoretical calculations for each of the three processes. The μ + μ − data are in good agreement with QED predictions. The π + π − cross-section, in our experimental acceptance, is somewhat larger than the one expected from the Born terms only.

1 data table
Table 1

EACH BEAM ENERGY VARIED BETWEEN 750 MEV AND 1 GEV.