Abstract
In this article, we review the status of the tension between the long-baseline accelerator neutrino experiments T2K and NOνA. The tension arises mostly due to the mismatch in the apappearance data of the two experiments. We explain how this tension arises based on νμ→νe and ν¯μ→ν¯e oscillation probabilities. We define the reference point of vacuum oscillation, maximal θ23 and δCP and compute the νe/ν¯e appearance events for each experiment. We then study the effects of deviating the unknown parameters from the reference point and the compatibility of any given set of values of unknown parameters with the data from T2K and NOνA. T2K observes a large excess in the νe appearance event sample compared to the expected νe events at the reference point, whereas NOνA observes a moderate excess. The large excess in T2K dictates that δCP be anchored at −90° and that θ23 > π/4 with a preference for normal hierarchy. The moderate excess at NOνA leads to two degenerate solutions: (a) NH, 0 < δCP < 180°, and θ23 > π/4; (b) IH, −180° < δCP < 0, and θ23 > π/4. This is the main cause of tension between the two experiments. We review the status of three beyond standard model (BSM) physics scenarios, (a) non-unitary mixing, (b) Lorentz invariance violation, and (c) non-standard neutrino interactions, to resolve the tension.
Highlights
Academic Editors: Chitta Ranjan Das, Timo J
T2K νe appearance channel is responsible for δCP being close to −90◦, and this is what leads to the tension between the NOνA and T2K data
A tension between the best-fit points of T2K and NOνA existed from the very beginning, which became only stronger with time
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. As a result of the way the labels 1, 2, and 3 are chosen, these mass-squared differences, in principle, can be either positive or negative Their signs have to be determined by experiments. The long-baseline reactor neutrino experiment KamLAND [24] has L ' 180 km At this long distance, it can observe oscillations due to the small mass-squared difference, ∆21. The long-baseline accelerator experiment MINOS [28] has a baseline of 730 km and it measured the survival probability of the accelerator νμ beam For this baseline and for accelerator neutrino energies, the oscillating term in P(νμ → νμ ) due to ∆21 is negligibly small. Among the neutrino oscillation parameters, the mass-squared differences and the mixing angles (except for θ23 ) are measured to a precision of a few percent.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
