Abstract
Ultra High Energy cosmogenic neutrinos may represent a unique opportunity to unveil possible new physics interactions once restricted to the neutrino sector only. In the present paper we study the observable effects of a secret active-sterile interactions, mediated by a pseudoscalar, on the expected flux of cosmogenic neutrinos. The results show that for masses of sterile neutrinos and pseudoscalars of hundreds MeV, necessary to evade cosmological, astrophysical and elementary particle constraints, the presence of such new interactions can significantly change the energy spectrum of cosmogenic neutrinos at Earth in the energy range from PeV to ZeV. Interestingly, the distortion of the spectrum results to be detectable at GRAND apparatus if the scalar mediator mass is around 250 MeV and the UHECRs are dominated by the proton component. Larger mediator masses or a chemical composition of UHECRs dominated by heavier nuclei would require much larger cosmic rays apparatus which might be available in future.
Highlights
The neutrino sector still represents a partially unknown territory
In this paper we have investigated the experimentally observable effects coming from a simple form of activesterile secret interactions in neutrino sector, mediated by a pseudoscalar, at air shower experiments like Giant Radio Array for Neutrino Detection (GRAND) and Pierre Auger Observatory (PAO)
In order to evade the constraints coming from cosmology, astrophysics and particle physics, we need to take quite a large mass for the sterile neutrinos of the order of few hundreds MeV
Summary
The neutrino sector still represents a partially unknown territory. Fundamental questions like the nature of neutrinos (Dirac or Majorana) or the possible connection of their small masses with physics beyond the Standard Model (BSM) can represent possible windows on new physics. In the last decade increasing attention has been devoted to high energy astrophysical neutrinos, after the observation of the first events at the IceCube detector [1] These astrophysical fluxes are of extreme relevance for the neutrino sector since they provide a powerful tool of investigation for beyond Standard Model physics, such as sterile neutrinos, Lorentz violations and nonstandard model interactions. A possible additional difficulty lies in the fact that cosmogenic neutrino fluxes have a strong dependence on the chemical composition of cosmic rays, as shown for instance in [38] This is important since recent results suggest that the chemical composition is mixed, containing significant amounts of heavier nuclei rather than protons [39], and for heavier nuclei one expects a suppression in the neutrino production. LSI 1⁄4 λνγ5νsφ; ð1Þ where λ is a dimensionless free coupling
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