English:
We report measurements by the T2K experiment of the parameters θ23 and ∆m232 governing the disappearance of muon neutrinos and antineutrinos in the three flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using 7.482 × 1020 POT in neutrino running mode and 7.471 × 1020 POT in antineutrino mode, T2K obtains sin2(θ23) = 0.51+0.08−0.07 and ∆m232 = 2.53+0.15−0.13 × 10−3 eV2/c4 for neutrinos, and sin2(θ̅23) = 0.47+0.25−0.07 and ∆m̅232 = 2.55+0.33−0.27 × 10−3 eV2/c4 for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed.
Top panels show the reconstructed energy distribution of the 135 far detector νμ-CCQE candidate events (left) and 66 ν̅μ-CCQE candidate events (right), with predicted spectra for best fit and no oscillation cases. Bottom panels show the ratio to unoscillated predictions.
日本語:
We report measurements by the T2K experiment of the parameters θ23 and ∆m232 governing the disappearance of muon neutrinos and antineutrinos in the three flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using 7.482 × 1020 POT in neutrino running mode and 7.471 × 1020 POT in antineutrino mode, T2K obtains sin2(θ23) = 0.51+0.08−0.07 and ∆m232 = 2.53+0.15−0.13 × 10−3 eV2/c4 for neutrinos, and sin2(θ̅23) = 0.47+0.25−0.07 and ∆m̅232 = 2.55+0.33−0.27 × 10−3 eV2/c4 for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed.
Top panels show the reconstructed energy distribution of the 135 far detector νμ-CCQE candidate events (left) and 66 ν̅μ-CCQE candidate events (right), with predicted spectra for best fit and no oscillation cases. Bottom panels show the ratio to unoscillated predictions.
