First JUNO Data Pinpoints Neutrino Oscillation Parameters with High Precision
JUNO's first 59.1 days of data from a 20-kton detector at 52.5 km from reactors yield a simultaneous, high-precision measurement of sin^2θ12 = 0.3092 ± 0.0087 and Δm21^2 = (7.50 ± 0.12)×10^-5 eV^2 for the normal mass ordering, improving precision by a factor of 1.6 over previous measurements and validating JUNO's design and energy calibration while showing readiness to determine the neutrino mass hierarchy with more data.