Energy-independent new physics in the flavour ratios of high-energy astrophysical neutrinos

Understand

We have studied the consequences of breaking the CPT symmetry in the neutrino sector, using the expected high-energy neutrino flux from distant cosmological sources such as active galaxies.

• For this purpose we have assumed three different hypotheses for the neutrino production model, characterised by the flavour fluxes at production \phi_e^0:\phi_\mu^0:\phi_\tau^0 = 1:2:0, 0:1:0, and 1:0:0, and studied the theoretical and experimental expectations for the muon-neutrino flux at Earth, \phi_\mu, and for the flavour ratios at Earth, R = \phi_\mu/\phi_e and S = \phi_\tau/\phi_\mu.
• CPT violation (CPTV) has been implemented by adding an energy-independent term to the standard neutrino oscillation Hamiltonian.
• This introduces three new mixing angles, two new eigenvalues and three new phases, all of which have currently unknown values.