Atmospheric neutrino constraints on Lorentz invariance violation with the first six detection units of KM3NeT/ORCA

Abstract

Lorentz invariance is a fundamental symmetry underlying both the Standard Model of particle physics and General Relativity. Testing its validity provides a direct means of searching for new physics emerging near the Planck scale. A search for isotropic Lorentz invariance violation with 1.4 years of atmospheric neutrino data collected by a partial configuration of the KM3NeT/ORCA detector comprising six detection units is presented. No evidence for such violation is found; thus, competitive limits are set on a subset of isotropic Lorentz invariance violating coefficients, which complement and extend existing experimental constraints.

Figures (6)

• Figure 1: Muon neutrino survival probability as a function of neutrino energy. The neutrino is assumed to have traversed the Earth with a baseline $L \simeq D_{\oplus}$. The effect of mass dimension $d = 3$ coefficients is illustrated in the left panel using different values of $\mathring{a}_{\mu\tau}^{(3)}$ as an example. The $d>3$ case is shown in the right panel, with $\mathring{c}_{\mu\tau}^{(4)}$ being chosen as a representative example. The values for $\mathring{a}_{\mu\tau}^{(3)}$ and $\mathring{c}_{\mu\tau}^{(4)}$ are the 90% (orange) and 99% (red) confidence level (CL) constraints reported by the IceCube collaboration in IC2yrLIV. The oscillation probabilities are computed using OscProb oscprob.
• Figure 2: Muon neutrino survival probability as a function of neutrino energy. The neutrino is assumed to have traversed the Earth with a baseline $L \simeq D_{\oplus}$. The left panel shows the effect of a nonzero $\mathring{k}_{ee}^{(d)}$, while the right panel illustrates the effect of a nonzero $\mathring{k}_{\mu\mu}^{(d)}$ and $- \mathring{k}_{\tau\tau}^{(d)}$, respectively. Mass dimension $d=3$ has been chosen as a representative example, using a coefficient value suitable for an illustration of LIV effects. The oscillation probabilities are computed using OscProb oscprob.
• Figure 3: Two-dimensional sensitivities for the magnitude and phase of $d=3$ off-diagonal coefficients. The 95% confidence level contour is shown in each panel.
• Figure 4: Likelihood ratio scans for $d=3$ off-diagonal coefficients. The intersections with the dashed lines define the upper limits.
• Figure 5: Likelihood-ratio scans for diagonal coefficient combinations across $d = 3, \dots, 8$. The blue dot in each panel indicates the respective best-fit point for that dimension. The intersections with the dashed lines define the upper limits.