The 21st International Workshop on Neutrinos from Accelerators (NUFACT2019)

Hierarchy independent sensitivity to leptonic δCP with low energy atmospheric neutrinos

26 Aug 2019, 19:00

2h 30m

Dynasty Hall (2F) (The Grand Hotel Daegu)

Board: 33

Poster Presentation Poster session

Speaker

Dr Lakshmi S Mohan (Dept. of Physics, Indian Institute of Technology Madras)

Description

One of the important unknowns in neutrino oscillation physics is the
the leptonic CP phase ${\delta }_{CP}$. Because of ambiguity between ${\delta }_{CP}$ and neutrino mass hierarchy, experiments have to be designed in such a way as to measure these parameters independent of each other. Long baseline experiments like DUNE is exclusively designed to measure ${\delta }_{CP}$ in regions without hierarchy ambiguity and atmospheric neutrino experiments like INO are designed to measure hierarchy without ${\delta }_{CP}$ ambiguity. However atmospheric neutrinos are not usually used to probe ${\delta }_{CP}$. Here we present the study that, at sub GeV energies atmospheric neutrinos can be used to probe ${\delta }_{CP}$ irrespective of mass hierarchy. We show that when the events are binned as a function of $(E_l,\cos {\theta }_l)$, the energy and direction of the final state leptons,a consistent distinction between various ${\delta }_{CP}$ values is obtained. Since there is no sensitivity to the mass ordering/hierarchy, ${\delta }_{CP}$ can be measured without hierarchy ambiguity at these energies. A ${\chi }^2$ analysis assuming a generic detector with perfect resolutions and efficiencies, and which can separate charged current ${\nu }_e,{\bar{\nu }}_e,{\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }$ events will also be discussed.