Abstract
Heavy sterile neutrinos are typically invoked to accommodate the observed neutrino masses, by positing a new Yukawa term connecting these new states to the neutrinos in the electroweak doublet. However, given our ignorance of the neutrino sector we should explore additional interactions such sterile neutrinos may have with the SM. In this paper, we study the dimension-5 operator which couples the heavy state to a light neutrino and the photon. We find that the recent XENON1T direct detection data can improve the limits on this "Neutrino Dipole Portal" by up to an order of magnitude over previous bounds. Future direct detection experiments may be able to extend these bounds down to the level probed by SN1987A.
Highlights
The fact that neutrinos are massive is one of the key observational facts indicating that the Standard Model (SM) of particle physics is incomplete
They may interact via a “neutrino dipole portal” interaction, which after electroweak symmetry breaking can be written as LNDP ⊃ dðνLσμνFμνNÞ þ H:c:; ð1Þ
We have shown that the recent XENON1T data can be used to constrain the neutrino dipole portal for tau flavour states at new levels of sensitivity
Summary
The fact that neutrinos are massive is one of the key observational facts indicating that the Standard Model (SM) of particle physics is incomplete. Most models of neutrino masses posit new right-handed states, which are singlets under the SM gauge groups. These neutral fermion singlets have been predominantly studied in connection with neutrino masses via the neutrino portal interaction, L ⊃ NHL, where N is the singlet fermion, L is the SM lepton doublet, and H is the Higgs doublet. We will study the neutrino dipole portal (NDP) at the XENON1T direct detection experiment using their approximately 1 ton-year exposure [11]. Muon- (Fig. 4) and especially tau-flavored (Fig. 1) interactions are sufficiently weakly constrained that the new bounds from direct detection experiments provide new sensitivity. III, we look at what improvements can come in the near term, focusing on a future run of SuperCDMS
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