Nonstandard Interactions and Prospects for Studying Standard Parameter Degeneracies in DUNE and T2HKK

Surender Verma,Shankita Bhardwaj

doi:10.1155/2019/8464535

Surender Verma, Shankita Bhardwaj

Open Access

https://doi.org/10.1155/2019/8464535

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Abstract

The future long baseline experiments such as DUNE and T2HKK have promising prospects to determine the neutrino mass hierarchy and measuring standard CP phase δ. However, presence of possible nonstandard interactions of neutrinos with matter may intricate this picture and is the subject matter of the present work. We have studied the standard parameter degeneracies in presence of nonstandard interactions (NSI) with DUNE and T2HKK experiments. We examine the mass hierarchy degeneracy assuming (i) all NSI parameters to be nonzero and (ii) one NSI parameter (ϵeμ) and its corresponding CP phase (δeμ) to be nonzero. We find that the latter case is more appropriate to resolve mass hierarchy degeneracy with DUNE and T2HKK experiments due to relatively small uncertainties emanating from the NSI sector. We have, also, investigated the octant degeneracy with neutrino (νμ→νe) and antineutrino (ν¯μ→ν¯e) mode separately. We find that to resolve this degeneracy the long baseline experiment with combination of neutrino and antineutrino mode is essential. Furthermore, we have considered DUNE in conjunction with T2HKK experiment to study CP phase degeneracy due to standard (δ) and nonstandard (δeμ) CP phases. We find that DUNE and T2HKK, in conjunction, have more sensitivity for CP violation effects (10σ for true NH and 8.2σ for true IH).

Highlights

The discovery of nonzero neutrino masses and lepton flavor mixing by the reactor [1], accelerator [2], atmospheric [3], and solar [4] neutrino oscillation experiments have revealed the values of oscillation parameters such as mass squared differences Δm221, |Δm231| and mixing angles θ12, θ23, θ13 [5], to an unprecedented accuracy
As the value of CP phases δ and δ푒휇 is not known and possible existence of CP violation in nature, we look for all possible values of δ(true), δ푒휇(true) which are distinct from the CP conserving values of δ and δ푒휇
In left panel of Figure 2, we have shown the mass hierarchy degeneracy assuming all nonstandard interactions (NSI) parameters, along with corresponding CP phases, to be nonzero for Deep Underground Neutrino Experiment (DUNE) and T2HKK experiments

Summary

Introduction

The discovery of nonzero neutrino masses and lepton flavor mixing by the reactor [1], accelerator [2], atmospheric [3], and solar [4] neutrino oscillation experiments have revealed the values of oscillation parameters such as mass squared differences Δm221, |Δm231| and mixing angles θ12, θ23, θ13 [5], to an unprecedented accuracy. In [8] the authors have studied the sensitivity to mass hierarchy, the octant of θ23, and CP phase δ in the future long baseline experiments T2HK and DUNE assuming standard interactions (SI) only. We have investigated prospects for lifting mass hierarchy degeneracy (sign degeneracy), θ23octant degeneracy, and CP-phase degeneracy in DUNE, T2HKK, and DUNE+T2HKK with matter NSIs. T2HKK is a long baseline experiment proposed to enhance the hierarchy sensitivity of T2HK by setting one of the two tanks of HK detector at a site in Korea. We have studied the standard parameter degeneracies, i.e., mass hierarchy degeneracy and octant degeneracy in presence of matter NSI with DUNE and T2HKK experiment.

Formalism

Experimental Setups

Parameter Degeneracies

25 True IH

Results and Discussion

Conclusions