CP-Violation with Neutrino Disappearance Alone

TL;DR

This paper demonstrates that CP violation in the lepton sector can be probed using only neutrino disappearance experiments by combining data from JUNO and DUNE or Hyper-Kamiokande, challenging the conventional focus on appearance modes.

Contribution

It introduces a novel approach to detect CP violation solely through disappearance experiments, expanding the methods available for neutrino CP studies.

Findings

Potential to disfavor certain CP phases at >3σ

Maximum sensitivity of 1.6σ over 6-13 years

Combining JUNO with DUNE or Hyper-Kamiokande enhances CP violation detection

Abstract

The best way to probe CP violation in the lepton sector is with long-baseline accelerator neutrino experiments in the appearance mode: the appearance of $\nu_e$ in predominantly $\nu_\mu$ beams. Here we show that it is possible to discover CP violation with disappearance experiments only, by combining JUNO for electron neutrinos and DUNE or Hyper-Kamiokande for muon neutrinos. While the maximum sensitivity to discover CP is quite modest ($1.6\sigma$ with 6 years of JUNO and 13 years of DUNE), some values of $\delta$ may be disfavored by $>3\sigma$ depending on the true value of $\delta$.