Speaker
Description
We present the first combination of light-by-light scattering ($\gamma\gamma\rightarrow \gamma\gamma$) cross-section measurements at LHC, using lead-lead data recorded by the ATLAS and CMS Collaborations at $5.02\,\text{TeV}$ and corresponding to integrated luminosities of 2.2 and $0.39\,\text{nb}^{-1}$, respectively. The combined cross-section is $115\pm 19\,\text{nb}$, with the two measurements contributing with factors of 0.8 and 0.2, accordingly. The combined result improves upon the best individual determination of $\gamma\gamma\rightarrow\gamma\gamma$ by approximately 10%, and it is consistent with the standard model prediction within two standard deviations. For the first time, we calculate the potential contribution of the $\eta_b(1S)$ meson production to the $\gamma\gamma\rightarrow\gamma\gamma$ invariant mass distributions, by calculating its inclusive photoproduction cross-section.
