First test of Lorentz violation with a reactor-based antineutrino experiment

We present a search for Lorentz violation with 8249 candidate electron antineutrino events taken by the Double Chooz experiment in 227.9 live days of running. This analysis, featuring a search for a sidereal time dependence of the events, is the first test of Lorentz invariance using a reactor-based antineutrino source. No sidereal variation is present in the data and the disappearance results are consistent with sidereal time independent oscillations. Under the Standard-Model Extension, we set the first limits on 14 Lorentz violating coefficients associated with transitions between electron and tau flavor, and set two competitive limits associated with transitions between electron and muon flavor.

Figure 1

The background subtracted data and MC expectation IBD event rates as a function of sidereal time. The MC expectation assumes no antineutrino disappearance. Total errors (statistical and systematic) are shown on the data points.

Figure 2

The electron antineutrino disappearance probability as a function of sidereal time overlaid with the best fit $e\mathrm{\text{−}}\mu$ (${\chi }^2/\mathrm{ndf}=28.8/21$) and $e\mathrm{\text{−}}\tau$ (${\chi }^2/\mathrm{ndf}=27.7/19$) curves. A one parameter flat fit to the distribution yields a best fit with ${\chi }^2/\mathrm{ndf}=30.6/23$.