https://doi.org/10.1140/epjc/s10052-021-08946-8
Regular Article - Theoretical Physics
From oscillation dip to oscillation valley in atmospheric neutrino experiments
1
Institute of Physics, Sachivalaya Marg, Sainik School Post, 751005, Bhubaneswar, India
2
Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, 400085, Mumbai, India
3
Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Block AF, Sector 1, Bidhannagar, 700064, Kolkata, India
4
Comenius University, Mlynská dolina F1, 842 48, Bratislava, Slovakia
5
International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy
6
Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, 400005, Mumbai, India
Received:
3
September
2020
Accepted:
2
February
2021
Published online:
25
February
2021
Atmospheric neutrino experiments can show the “oscillation dip” feature in data, due to their sensitivity over a large L/E range. In experiments that can distinguish between neutrinos and antineutrinos, like INO, oscillation dips can be observed in both these channels separately. We present the dip-identification algorithm employing a data-driven approach – one that uses the asymmetry in the upward-going and downward-going events, binned in the reconstructed L/E of muons – to demonstrate the dip, which would confirm the oscillation hypothesis. We further propose, for the first time, the identification of an “oscillation valley” in the reconstructed (
,
) plane, feasible for detectors like ICAL having excellent muon energy and direction resolutions. We illustrate how this two-dimensional valley would offer a clear visual representation and test of the L/E dependence, the alignment of the valley quantifying the atmospheric mass-squared difference. Owing to the charge identification capability of the ICAL detector at INO, we always present our results using 
and 
events separately. Taking into account the statistical fluctuations and systematic errors, and varying oscillation parameters over their currently allowed ranges, we estimate the precision to which atmospheric neutrino oscillation parameters would be determined with the 10-year simulated data at ICAL using our procedure.
© The Author(s) 2021
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