Heavy neutrino production via ZZ' at the lifetime frontier


We investigate the pair production of right-handed neutrinos from the decay of an additional neutral ZZ^{\prime} boson in the gauged BLB-L model. Taking into account current constraints on the ZZ^{\prime} mass and the associated gauge coupling g1g_{1}^{\prime}, we analyse the sensitivity of proposed experiments at the lifetime frontier, FASER 2, CODEX-b, MATHUSLA as well as a hypothetical version of the MAPP detector to a long lived heavy neutrino NN originating in the decays of the ZZ^{\prime}. We further complement this study with determining the reach of LHCb and a CMS-type detector for the high-luminosity LHC run. We demonstrate that in a background free scenario with g1=103g_1^\prime = 10^{-3} near the current limit, FASER 2 is sensitive to the active-sterile neutrino mixing down to VμN104V_{\mu N} \approx 10^{-4}, while a reach of VμN105V_{\mu N} \approx 10^{-5} can be obtained for CODEX-b and LHCb, in a mass regime of mN520m_N \approx 5-20 GeV and mZ2070m_{Z^{\prime}} \approx 20-70 GeV. Finally, MATHUSLA can probe VμN107V_{\mu N} \approx 10^{-7} and cover the mixing regime expected in a canonical seesaw scenario of light neutrino mass generation.Comment: 20 pages, 6 figures, matches published versio

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