Limits on Low Energy Photon-Photon Scattering from an Experiment on Magnetic Vacuum Birefringence

Experimental bounds on induced vacuum magnetic birefringence can be used to improve present photon-photon scattering limits in the electronvolt energy range. Measurements with the Polarizzazione del Vuoto con Laser apparatus [E. Zavattini et al., Phys. Rev. D 77, 032006 (2008)] at both {lambda}=1064 and 532 nm lead to bounds on the parameter A{sub e}, describing nonlinear effects in QED, of A{sub e}{sup (1064)}<6.6x10{sup -21} T{sup -2}-1064 nm and A{sub e}{sup (532)}<6.3x10{sup -21} T{sup -2}-532 nm, respectively, at 95% confidence level, compared to the predicted value of A{sub e}=1.32x10{sup -24} T{sup -2}. The total photon-photon scattering cross section may also be expressed in terms of A{sub e}, setting bounds for unpolarized light of {sigma}{sub {gamma}}{sub {gamma}}{sup (1064)}<4.6x10{sup -62} m{sup 2} and {sigma}{sub {gamma}}{sub {gamma}}{sup (532)}<2.7x10{sup -60} m{sup 2}. Compared to the expected QED scattering cross section these results are a factor of {approx_equal}2x10{sup 7} higher and represent an improvement of a factor about 500 on previous bounds based on ellipticity measurements and of a factor of about 10{sup 10} on bounds based on direct stimulated scattering measurements.