Observation of Light-by-Light Scattering and Search for Axion-Like Particles with CMS Experiment

Light-by-light (LbL) scattering ($\gamma \gamma \rightarrow \gamma \gamma $) is a fundamental quantum mechanical process which could not be observed until recently due to its tiny cross section. By using huge photon fluxes from lead-on-lead (PbPb) ultraperipheral collisions (UPCs), the process has now been observed by both ATLAS and CMS experiments. LbL process is also a sensitive channel to probe physics beyond the standard model where an intermediate pseudoscalar, axion-like-particle (a) could be produced, i.e., ($\gamma \gamma \rightarrow a \rightarrow \gamma \gamma $). The diphoton invariant mass distribution of LbL process is used to search for such a resonance production. A new exclusion limits on the mass of the pseudoscalar axion-like particles, in the range of 5–90 GeV has been set. This report will discuss highlights of the measurement of LbL scattering by CMS experiment.