Neutrino flavor oscillations in a rotating spacetime

Abstract

We study neutrino oscillations in a rotating spacetime under the weak gravity limit for the neutrino trajectories constrained in the equatorial plane. Using the asymptotic form of the Kerr metric, we show that the gravitational source's rotation non-trivially modifies the neutrino phase. Further, we find that the flavor transition probability deviates more prominently from the Schwarzschild spacetime results when neutrinos are produced and detected on the same side of the gravitational source, i.e., neutrino propagates only towards or away from the gravitational source. For the neutrino weak gravity lensing in the equatorial plane, we find that the effects of gravitational object spin on the neutrino phase are subdominant compared with the Schwarzschild spacetime neutrino phase. However, the rotational effect can be comparable with the gravitational mass effect in the neutrino lensing if the naked singularity condition that bounds the Kerr rotation is violated. Furthermore, we find that the neutrino phase for the non-radial neutrino emission depends on the relative angular momentum direction of the neutrino and the gravitational source. For an asymptotic observer, we find that the neutrino phase, in the leading orders of gravitational spin corrections, differs from the Schwarzschild spacetime due to the difference in the proper spatial distance of the neutrino trajectory that connects the neutrino source and the detector. In contrast, the higher-order terms, other than those arriving from the proper spatial distance, which lead to the deviation from the Schwarzschild spacetime neutrino phase, are significantly suppressed. Further, we discuss neutrino gravitational decoherence. We find that decoherence length is also sensitive to the relative direction of the neutrino angular momentum and the gravitational source rotation. Finally, we demonstrate results using numerical examples.

Gravitational waves and neutrino oscillations in Chern-Simons axion gravity

“…After the recent success in experimental studies, it has been determined that neutrinos are massive particles and have nonzero mixing between different flavors that leads to flavor oscillations. External fields can significantly modify the process of neutrino oscillations and therefore the gravitational interaction can have observable effects on the propagation and oscillation of neutrino flavor [81][82][83][84][85][86][87][88][89][90][91][92][93][94][95]. In particular, we will take into account the contribution of GW following Ref.…”