From oscillation dip to oscillation valley in atmospheric neutrino experiments Anil Kumar, Amina Khatun, Sanjib Kumar Agarwalla and Amol Dighe Eur. Phys. J. C, 81 2 (2021) 190 Published online: 25 February 2021 DOI: 10.1140/epjc/s10052-021-08946-8