Probing ALP-sterile neutrino couplings at the LHC

Abstract

In this work, prospects to probe an overlooked facet of axion-like particles (ALPs)-their potential couplings to sterile neutrinos-are presented. We found that mono-photon searches have the potential to constrain ALP couplings to sterile neutrinos when a new heavy scalar boosts the ALP decay yields. Working within an effective field theory (EFT) approach, we scan the parameters space to establish the reach of the 13 TeV LHC to probe such couplings. We found regions of the parameters space evading several experimental constraints that can be probed at the LHC. Moreover, a complementary role between the LHC and various experiments that search for axions and ALPs can be anticipated for models where ALPs interact with sterile neutrinos. We also present the UV realization of a model having an axion-like particle, a heavy scalar and sterile neutrinos whose parameters are spanned by our EFT approach. The proposed model contains a type of seesaw mechanism for generating masses for the active neutrinos along with sterile neutrinos involving the high energy scale of the spontaneous breaking of the global symmetry associated to the ALP. Some benchmark points of this model can be discovered at the 13 TeV LHC with 300 fb −1 .

Explaining the MiniBooNE Anomalous Excess via Leptophilic ALP-Sterile Neutrino Coupling

“…In this model, we assume that the ALP has a coupling to the sterile neutrino. Such coupling can be generated by introducing a complex singlet scalar field Φ and a pair of left and right chiral fermionic fields ψ L,R , of the interactions as [16]…”

“…What is relevant for us is the interactions of ALP with the sterile neutrino and electron. Assuming, for simplicity, the interaction is diagonal in the flavor eigenstates of leptons, the effective Lagrangian density can be written as [16]…”

White Paper on Light Sterile Neutrino Searches and Related Phenomenology

“…Reactors have played an important role in neutrino physics since their discovery because they are prodigious generators of electron-flavor antineutrinos (ν e ). Reactor νe are produced from beta decays of neutron-rich fission fragments generated by the heavy fissionable isotopes 235 U, 238 U, 239 Pu, and 241 Pu. After their production in the reactor core, these MeV-scale νe are emitted isotropically.…”

“…The modern converted νe spectra by Mueller et al [54] and Huber [55] (HM model) are based on the β-decay measurements of the isotopes 235 U, 239 Pu, 241 Pu performed at the Institut Laue-Langevin (ILL) in the early 1980s [56][57][58]. An aggregate fission beta spectrum measurement of 238 U was not performed at ILL 3 , since fission of 238 U required neutrons with energies higher than those available at the thermal ILL facility. Ref.…”

Axions: From Magnetars and Neutron Star Mergers to Beam Dumps and BECs

“…Exotic decays of Z or Higgs also can be good channels to look for ALP signals [360,376,413]. Finally, the scenario that ALP couples to sterile neutrinos and its collider signature were investigated [414].…”