Testing the non-unitarity of the leptonic mixing matrix at FASERν and FASERν2

The FASERν experiment has detected the first neutrino events coming from LHC. Near future high-statistic neutrino samples will allow us to search for new physics within the neutrino sector. Motivated by the forthcoming promising FASERν neutrino data, and its succesor, FASERν2, we study its potential for testing the unitarity of the neutrino lepton mixing matrix. Although it would be challenging for FASERν and FASERν2 to have strong constraints on this kind of new physics, we discuss its role in contributing to a future improved global analysis.