First Search for Dark-Trident Processes Using 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, Madhumita Bhattacharya, M. Bishai, A. Blake, B. Bogart, T. Bolton, J. Y. Book, M. B. Brunetti, L. Camilleri, Y. Cao, D. Caratelli, F. Cavanna, G. Cerati, A. Chappell, Y. Chen, J. M. Conrad, J. M. Conrad, L. Cooper-Troendle, J. I. Crespo-Anadón, Ryan Cross, M. Del Tutto, S. R. Dennis, P. Detje, A. 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, P. Green, L. Gu, Wei Gu, R. Guénette, P. Guzowski, L. Hagaman, O. Hen, C. Hilgenberg, G. A. Horton-Smith, Z. Imani, B. Irwin, M. S. Ismail, C. James, Xiangpan 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. Martínez Caicedo
Abstract
We present a first search for dark-trident scattering in a neutrino beam using a dataset corresponding to 7.2×10^{20} protons on target taken with the MicroBooNE detector at Fermilab. Proton interactions in the neutrino target at the main injector produce π^{0} and η mesons, which could decay into dark-matter (DM) particles mediated via a dark photon A^{'}. A convolutional neural network is trained to identify interactions of the DM particles in the liquid-argon time projection chamber (LArTPC) exploiting its imagelike reconstruction capability. In the absence of a DM signal, we provide limits at the 90% confidence level on the squared kinematic mixing parameter ϵ^{2} as a function of the dark-photon mass in the range 10≤M_{A^{'}}≤400 MeV. The limits cover previously unconstrained parameter space for the production of fermion or scalar DM particles χ for two benchmark models with mass ratios M_{χ}/M_{A^{'}}=0.6 and 2 and for dark fine-structure constants 0.1≤α_{D}≤1.