Probing sterile neutrinos in B (D) meson decays at Belle II (BESIII) C. S. Kim, Youngjoon Kwon, Donghun Lee, Sechul Oh and Dibyakrupa Sahoo Eur. Phys. J. C, 80 8 (2020) 730 Published online: 12 August 2020 DOI: 10.1140/epjc/s10052-020-8310-2