Search for Heavy Neutral Leptons in Electron-Positron and Neutral-Pion Final States with the MicroBooNE Detector
P. Abratenko, O. Alterkait, D. Andrade Aldana, L. Arellano, J. Asaadi, A. Ashkenazi, S. Balasubramanian, B. Baller, G. Barr, D. Barrow, J. Barrow, V. Basque, O. Benevides Rodrigues, S. Berkman, A. Bhanderi, A. Bhat, M. Bhattacharya, M. Bishai, A. Blake, B. Bogart, T. Bolton, J. Y. Book, M. B. Brunetti, L. Camilleri, Y. Cao, D. Caratelli, F. Cavanna, G. B. Cerati, A. Chappell, Y. Chen, J. M. Conrad, M. Convery, L. Cooper-Troendle, J. I. Crespo-Anadón, Ryan Cross, M. Del Tutto, S. R. Dennis, P. Detje, Ann Devitt, R. Diurba, K. Duffy, R. Dorrill, K. Duffy, S. Dytman, B. Eberly, P. Englezos, A. Ereditato, J. J. Evans, R. Fine, O. G. Finnerud, W. Foreman, B. T. Fleming, D. Franco, A. P. Furmanski, F. Gao, D. García-Gámez, S. Gardiner, G. Ge, S. Gollapinni, E. Gramellini, P. Green, H. Greenlee, L. Gu, W. Gu, R. Guénette, P. Guzowski, L. Hagaman, O. Hen, C. Hilgenberg, G. A. Horton-Smith, Z. Imani, B. Irwin, M. Ismail, C. James, X. Ji, J. H. Jo, R. A. Johnson, Y.-J. Jwa, D. Kalra, N. Kamp, G. Karagiorgi, W. Ketchum, M. Kirby, T. Kobilarcik, I. Kreslo, M. B. Leibovitch, I. Lepetic, J.-Y. Li, K. Li, Y. Li, K. Lin, B. R. Littlejohn, H. Liu, W. C. Louis, X. Luo, C. Mariani, D. Marsden, J. Marshall, N. Martinez, D. A. Martinez Caicedo
Abstract
We present the first search for heavy neutral leptons (HNLs) decaying into νe^{+}e^{-} or νπ^{0} final states in a liquid-argon time projection chamber using data collected with the MicroBooNE detector. The data were recorded synchronously with the NuMI neutrino beam from Fermilab's main injector corresponding to a total exposure of 7.01×10^{20} protons on target. We set upper limits at the 90% confidence level on the mixing parameter |U_{μ4}|^{2} in the mass ranges 10≤m_{HNL}≤150 MeV for the νe^{+}e^{-} channel and 150≤m_{HNL}≤245 MeV for the νπ^{0} channel, assuming |U_{e4}|^{2}=|U_{τ4}|^{2}=0. These limits represent the most stringent constraints in the mass range 35<m_{HNL}<175 MeV and the first constraints from a direct search for νπ^{0} decays.