Abstract
The neutrino physics program at the LHC, which will soon be initiated by the FASER experiment, will provide unique opportunities for precision studies of neutrino interaction vertices at high energies. This will also open up the possibility to search for beyond the standard model (BSM) particles produced in such interactions in the specific high-energy neutrino beam-dump experiment. In this study, we illustrate the prospects for such searches in models with the dipole or Z′ portal to GeV-scale heavy neutral leptons. To this end, we employ both the standard signature of new physics that consists of a pair of oppositely-charged tracks appearing in the decay vessel, and the additional types of searches. These include high-energy photons and single scattered electrons. We show that such a variety of experimental signatures could significantly extend the sensitivity reach of the future multi-purpose FASER 2 detector during the High-Luminosity phase of the LHC.
Highlights
In the intermediate energy range, Eν ∼ TeV, the properties of neutrinos are generally expected to follow the Standard Model (SM) predictions
We have identified the simplified beyond the standard model (BSM) models of our interest such that they illustrate a number of ways in which new physics signals could be observed in neutrino interactions in the FASER and FASER 2 multi-purpose detectors
From the bottom to the top, the lines correspond to Nev = 3 and 30 expected such events during the HL-Large Hadron Collider (LHC) phase, while we have suppressed the lines corresponding to larger values of Nev for clarity of the plot
Summary
Despite a large number of forward-going neutrinos at the LHC, only few of them will interact in the detector due to their tiny scattering cross section. The events rates, become significantly larger in the presence of light mediator particle X between neutrinos and other SM fermions. In this case, for low momentum exchange and gD4 /m4X ∼ G2F , where GF 1.166 × 10−5 GeV−2 is the Fermi coupling constant [7], the Fermi contact interaction of neutrinos in the SM can be supplemented by a similar BSM contribution to the total cross section. [43,44,45] for review of this rich experimental program) These could be associated with both the primary production of new physics species in the target material and with the secondary interactions of neutrinos. We refer to specific such searches relevant for the models under study
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