Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV
Phys.Lett. B797 (2019) 134826, 2019.
The collaboration

Abstract (data abstract)
Measurement of the fiducial cross section of light-by-light scattering and exclusion limits on axion-like-particles in lead-lead collisions at a centre-of-mass energy of 5.02 TeV with 390 mub^-1 of data collected in 2015. The fiducial region is defined as: - 2Gamma - pt_Gamma > 2 GeV - $|\eta_{\gamma}| < 2.4$ - exluding 1.444<|$\eta$|<1.566 region - m_GammaGamma > 5 GeV - pt_GammaGamma < 1 GeV - aco_GammaGamma < 0.01