Right-handed neutrino production through first-generation leptoquarks

The collider phenomenology of leptoquarks (LQs) and right-handed neutrinos (RHNs) has been studied extensively in the literature. Due to their gauge singlet nature, the production of RHNs at the LHC is typically suppressed by the tiny light-heavy neutrino mixing angles. In this study, we explore a promising scenario where the presence of a LQ mediator significantly enhances the RHN production: the LQ essentially couples only to first-generation fermions (quarks and leptons, including the RHN), and the coupling with the first-generation RHN dominates. We consider all possible scalar and vector LQs that could lead to such a scenario. The prospects are better for the first-generation scenario than the other generations because of the enhanced parton distribution functions (PDFs) of first-generation quarks. The enhanced PDFs boost the production cross sections of LQs, particularly their single and indirect productions. Incorporating all production modes of LQs that result in a pair of RHNs, we estimate the discovery prospects by analyzing the monoelectron and dielectron channels arising from the decay of the RHN pair. We find that the indirect production of LQs is crucial in determining the discovery reach at the HL-LHC for the first-generation scenario. Published by the American Physical Society 2025