Sensitivities to secret neutrino interaction at FASERν

We study the impact of the coupling of neutrinos with a new light neutral gauge boson, Z′, with a mass of less than 500 MeV in FASERν experiment. Scenarios in which a light gauge boson is coupled to neutrinos are motivated within numerous contexts which are designed to explain various anomalies in particle physics and cosmology. This interaction leads to a new decay mode for charged mesons to a light lepton plus neutrino and Z′, (M ⁺ → l ⁺ νZ′), followed by the subsequent decay of Z′ into the pair of neutrino and anti-neutrino, ($Z^{\prime }\to \nu \overline{\nu }$). FASERν, the Forward Search Experiment at the Large Hadron Collider, has the potential to detect collider neutrinos for the first time. In particular, the FASERν emulsion detector will provide the opportunity to detect τ-neutrinos and to measure their energies. Using this ability of FASERν emulsion detector, we investigate the potential of FASERν experiment and the proposed upgraded version of this experiment, FASER2ν, to constrain the coupling of a neutrino with the light gauge boson. (paper)