Abstract
The Dirac leptonic CP phase {\delta}_CP is one of the crucial unknown parameters in neutrino oscillation physics. In this paper we explore the possibility of using low energy atmospheric neutrino events to probe {\delta}_CP . We show that at sub GeV energies, when the events are binned as a function of the energy and direction of the final state leptons, a consistent distinction between various true {\delta}_CP values is obtained. We also show that at these energies there is no sensitivity to the mass ordering/hierarchy, so that {\delta}_CP can be measured without hierarchy ambiguity. In addition a preliminary \c{hi}^2 analysis of the sensitivity to {\delta}_CP using atmospheric neutrinos assuming a generic detector with perfect separation between charged current {\nu}_{\mu} , \bar{{\nu}}_{\mu} , {\nu}_e and \bar{{\nu}}_e events is given.
Highlights
The Dirac leptonic phase δCP is one of the important unknown parameters in neutrino oscillation physics today
In this paper we explore the possibility of using low energy atmospheric neutrino events to probe δCP
We explore the possibility of using atmospheric neutrino events, especially in the sub-GeV region (Eν ≤ 1 GeV) to probe the CP phase
Summary
The Dirac leptonic phase δCP is one of the important unknown parameters in neutrino oscillation physics today. Mainly accelerator long baseline (LBL) experiments are running or are being designed to measure this parameter as precisely as possible [2,3,4] These experiments have very good sensitivity to δCP but its extraction mostly depends on the hierarchy, whether normal or inverted, in the neutrino masses. The dependence on the CP phase (of the angular distribution) of νe and νμ events is such that it systematically shifts the observed event rates in opposite directions in the two cases This dependence on CP is independent of the mass hierarchy. Atmospheric neutrino events are uniquely positioned so that low energy sub-GeV events are sensitive to δCP independent of MH, while higher energy (few GeV) events are sensitive to MH independent of δCP We believe that this unique dependence has been discussed for the first time, in this paper.
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