Decoherence in neutrino propagation through matter, and bounds from IceCube/DeepCore

Abstract

Abstract We revisit neutrino oscillations in matter considering the open quantum system framework, which allows to introduce possible decoherence effects generated by New Physics in a phenomenological manner. We assume that the decoherence parameters $$\gamma _{ij}$$ γij may depend on the neutrino energy, as $$\gamma _{ij}=\gamma _{ij}^{0}(E/\text {GeV})^n\ (n = 0,\pm 1,\pm 2) $$ γij=γij0(E/GeV)n(n=0,±1,±2) . The case of non-uniform matter is studied in detail and, in particular, we develop a consistent formalism to study the non-adiabatic case dividing the matter profile into an arbitrary number of layers of constant densities. This formalism is then applied to explore the sensitivity of IceCube and DeepCore to this type of effects. Our study is the first atmospheric neutrino analysis where a consistent treatment of the matter effects in the three-neutrino case is performed in presence of decoherence. We show that matter effects are indeed extremely relevant in this context. We find that IceCube is able to considerably improve over current bounds in the solar sector ($$\gamma _{21}$$ γ21 ) and in the atmospheric sector ($$\gamma _{31}$$ γ31 and $$\gamma _{32}$$ γ32 ) for $$n=0,1,2$$ n=0,1,2 and, in particular, by several orders of magnitude (between 3 and 9) for the $$n=1,2$$ n=1,2 cases. For $$n=0$$ n=0 we find $$\gamma _{32},\gamma _{31}< 4.0\times 10^{-24}\, (1.3\times 10^{-24})\ \hbox {GeV}$$ γ32,γ31<4.0×10-24(1.3×10-24)GeV and $$\gamma _{21}<1.3\times 10^{-24}\, (4.1\times 10^{-24})\ \hbox {GeV}$$ γ21<1.3×10-24(4.1×10-24)GeV at the 95% CL, for normal (inverted) mass ordering.