Jan 10 – 14, 2022
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Establishing non-maximal 2-3 mixing with DUNE in light of current neutrino oscillation data

Jan 11, 2022, 2:00 PM
20m
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Online only

Parallel session talk Neutrinos Neutrino physics

Speaker

Ritam Kundu (Institute of Physics, Bhubaneswar, India)

Description

Global analyses [1-3] of the existing neutrino oscillation data point to near--percent-level relative $1\sigma$-precision in oscillation parameters such as $\vert \Delta m^2_{31} \vert $ $ \left(1.1\%\right)$, $\Delta m^2_{21} $ $ \left(2.3\%\right)$, $\sin^2\theta_{13} $ $\left(3.0\%\right)$ and $\sin^2\theta_{12}\left(4.5\%\right)$. All these analyses show a preference for the normal mass ordering, thus disfavoring the inverted mass ordering at nearly $\sim 2.5\sigma$. Refs. [1] and [2] find the best fit for $\theta_{23}$ in the higher octant at $\sin^2\theta_{23}\sim 0.57$ while Ref. [3] finds the best fit for $\theta_{23}$ in the lower octant at $\sin^2\theta_{23}\sim 0.46$. All three of them allow the solution in the other octant at $2\sigma$ or less. It should also be noted that all these analyses allow maximal 2-3 mixing i.e. the value $\sin^2\theta_{23} = 0.5$ at $\sim$ $2.5\sigma$ or less. The primary goal of the next-generation experiments such as the Deep Underground Neutrino Experiment (DUNE) [4] is to {\it conclusively} find out the sign of $m^2_{3} - m^2_{1}$, the value of $\sin^2\theta_{23}$, the existence of leptonic CP-violation in neutrino sector and the value of its phase $\delta_{\rm CP}$. The main aim of this work is to explore if DUNE can conclusively rule-out maximal 2-3 mixing if the true $1\sigma$ range of $\sin^2\theta_{23}$ is $\sim\left(0.44,~0.47\right)$ as indicated in Ref. [3]. Our work highlights that while this measurement is, by and large, independent of the systematic uncertainties and an imprecise understanding of $\delta_{\rm CP}$; it crucially depends on performing a spectral analysis to resolve the $\vert \Delta m^2_{31} \vert$--$\sin^2\theta_{23}$ degeneracy - a feature that can potentially ruin DUNE's sensitivity for $\sin^2\theta_{23}$ resolution if $\vert \Delta m^2_{31} \vert$ is not known accurately-enough. We find that disappearance data from DUNE can improve the current precision in the measurements of $\vert \Delta m^2_{31} \vert$ and $\sin^22\theta_{23}$ by a factor of three while the appearance data can very effectively eliminate the wrong-octant solution. {\it Our results show that DUNE can exclude $\sin^2\theta_{23}=0.5$ at $\sim 2\sigma$ for the current $1\sigma$-upper bound of $\sin^2\theta_{23}\sim 0.47$. For the current best-fit of $\sin^2\theta_{23}=0.455$, a $\sim 4\sigma$ exclusion is possible.

Primary authors

Masoom Singh (Institute of Physics and Utkal University, Bhubaneswar, India) Ritam Kundu (Institute of Physics, Bhubaneswar, India) Dr Sanjib Kumar Agarwalla (Institute of Physics, Bhubaneswar, India) Dr Suprabh Prakash (The Institute of Mathematical Sciences, Chennai, India)

Presentation materials