2025/08/14 by A, ShivaSankar K., Das, Souvik, Das, Arindam +1 · 3 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2508.10734
We study two general U(1) extensions of the Standard Model (SM) those generate tiny neutrino masses via the seesaw mechanism after general U(1) breaking. These models predict a new neutral gauge boson (Z') and right-handed neutrinos (RHNs), the latter introduced for anomaly cancellation and neutrino mass generation. In both scenarios, left- and right-handed fermions couple differently to the Z', and RHNs mix with light neutrinos, enabling variety of decay modes. Focusing on the high-luminosity LHC (HL-LHC) and the future FASER2 experiment, we explore RHN pair production from Z' decays in two cases: (i) long-lived Z' decays to visible modes and long-lived RHNs, and (ii) short-lived Z' decays to long-lived RHNs, which further decay visibly inside FASER2. We estimate projected limits on the general U(1) gauge coupling, Z' mass, RHN mass, and light-heavy neutrino mixing for various U(1) charge assignments, and compare them with current experimental bounds.