Indications of Neutrino Oscillation in a 250 km Long-Baseline Experiment

Abstract

The K2K experiment observes indications of neutrino oscillation: a reduction of nu(mu) flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of 80.1(+6.2)(-5.4). Twenty-nine one ring mu-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%.

Coherence and Wave Packets in Neutrino Oscillations

“…However, recently the KamLAND experiment [25] observed indications in favor of distance and energy dependent oscillations in vacuum of reactor antineutrinos due to the same mass-squared difference responsible of solar neutrino oscillations. Distance and energy dependent flavor-changing transitions have been also observed in the Super-Kamiokande [29], Soudan 2 [5] and MACRO [7] atmospheric neutrino experiments and in the long-baseline experiment K2K [4]. These experimental evidences show without any doubt that the arguments presented in Ref.…”

“…Although in laboratory experiments it is possible to measure neutrino oscillations in time through the measurement of both the production and detection processes (see Ref. [64]) 4 , in all existing neutrino oscillation experiments only the sourcedetector distance is known. In this case the relevant density matrix operatorρ α (x) is given by the time average ofρ α (x, t).…”

Neutrino oscillations from relativistic flavor currents

“…The recent experimental evidence [1,2,3,4,5] of neutrino mixing and oscillations [6] is the first clear sign of physics beyond the Standard Model [7]. Thus much effort is currently devoted to the full understanding of such phenomenon, from the issue of its origin to more phenomenological ones.…”

Statistical Pattern Recognition: Application to νμ→ντOscillation Searches Based on Kinematic Criteria

“…Results from experiments carried out with neutrinos produced in artificial sources, like reactors and accelerators, strongly support the fact that neutrinos are massive [4,5].…”