Violation of Equivalence Principle at IceCube

Abstract

We study the effects of a Violation of Equivalence Principle (VEP) on neutrino oscillations. We analyze the IceCube data on atmospheric neutrino fluxes to obtain updated constraints on the parameter space of VEP, with the benchmark choice that neutrinos with different masses couple with different strengths to the gravitational field. We find that the VEP parameters times the local gravitational potential at Earth can be constrained at the level of 10−27. The constraints from atmospheric neutrinos strongly depend on the assumption that the neutrino eigenstates interacting diagonally with the gravitational field coincide with the mass eigenstates, which is not a priori justified: as an example, if the basis of diagonal gravitational interaction coincide with the flavor basis, atmospheric neutrinos cannot constrain the model. Finally, we quantitatively study the effect of a VEP on the flavor composition of the astrophysical neutrinos, stressing again the interplay with the basis in which the VEP is diagonal: we find that some choices of such basis are already in tension with the flavor ratio of the diffuse neutrino flux measured by IceCube.