Updated fit to three neutrino mixing: exploring the accelerator-reactor complementarity

Abstract

We perform a combined fit to global neutrino oscillation data available as of fall 2016 in the scenario of three-neutrino oscillations and present updated allowed ranges of the six oscillation parameters. We discuss the differences arising between the consistent combination of the data samples from accelerator and reactor experiments compared to partial combinations. We quantify the confidence in the determination of the less precisely known parameters θ 23 , δ CP , and the neutrino mass ordering by performing a Monte Carlo study of the long baseline accelerator and reactor data. We find that the sensitivity to the mass ordering and the θ 23 octant is below 1σ. Maximal θ 23 mixing is allowed at slightly more than 90% CL. The best fit for the CP violating phase is around 270 • , CP conservation is allowed at slightly above 1σ, and values of δ CP 90 • are disfavored at around 99% CL for normal ordering and higher CL for inverted ordering.

A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (ν) and μ-DAR ν ¯ $$ \left(\overline{\nu}\right) $$

“…Now, it would be interesting to see how the octant sensitivity of these setups varies with the different true choices of θ 23 . We present these results in figure 8 assuming δ CP true = −90 • , which is close to the best-fit value as hinted by present world neutrino data [15,16]. If the hierarchy is unknown (known), the top (bottom) panels of this figure portray the range of true θ 23 for which the wrong octant can be excluded at a given confidence level.…”

“…[15], the current oscillation data show an overall preference for NH with respect to IH at the level of ∼ 2σ, which mainly stems from the Super-Kamiokande atmospheric data. The complementarity among the various data sets provided by the accelerator and reactor experiments has already enabled us to probe the parameter space for the δ CP phase [15,16]. Currently, we have a hint in favor of δ CP around −90 • and this trend is getting strengthened day by day.…”

Breakings of the neutrino μ-τ reflection symmetry

“…interesting to find that the best-fit result for δ is around 270 • (261 • ± 55 • for NH and 277 • ± 43 • for IH) [5].…”

Broken S 3L × S 3R flavor symmetry and leptonic CP violation

“…1(a the ratio of two neutrino mass-squared differences ∆m 2 21 /∆m 2 31 , and the mixing parameters (c) (sin 2 θ 12 ,sin 2 θ 23 ) and (d) (sin 2 θ 13 ,δ), where the 3σ ranges of neutrino mixing parameters in Eqs. (21) and (22) have been used [6].…”

“…The latest global analysis of neutrino oscillation data [6] yields the best-fit values of the three mixing angles as θ 12 ≈ 33.6 • , θ 13 ≈ 8.5 • and θ 23 ≈ 41.6 • , and those of the two neutrino mass-squared differences as ∆m 2 21 ≡ m 2 2 − m 2 1 ≈ 7.50 × 10 −5 eV 2 and ∆m 2 31 ≡ m 2 3 −m 2 1 ≈ 2.52×10 −3 eV 2 . Although the normal ordering of neutrino masses (i.e., m 1 < m 2 < m 3 ) is slightly favored and there is a preliminary hint of a nearly-maximal CP -violating phase δ ≈ 261 • or equivalently δ ≈ −99 • , the possibility of an inverted mass ordering (i.e., m 3 < m 1 < m 2 ) and CP conservation in the leptonic sector has not yet been excluded [6]. See also the independent global-fit results from two other groups [7][8][9].…”