Blake, A. and Devitt, A. and Gu, L. and Mawby, I. and Nowak, J. and Patel, N. and Pophale, I. (2024) First search for dark-trident processes using the MicroBooNE detector. Physical review letters, 132 (24). ISSN 1079-7114
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dark_tridents_paper-6.pdf - Accepted Version
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Abstract
We present a first search for dark-trident scattering in a neutrino beam using a data set corresponding to $7.2 \times 10^{20}$ protons on target taken with the MicroBooNE detector at Fermilab. Proton interactions in the neutrino target at the Main Injector produce $\pi^0$ and $\eta$ mesons, which could decay into dark-matter (DM) particles mediated via a dark photon $A^\prime$. A convolutional neural network is trained to identify interactions of the DM particles in the liquid-argon time projection chamber (LArTPC) exploiting its image-like reconstruction capability. In the absence of a DM signal, we provide limits at the $90\%$ confidence level on the squared kinematic mixing parameter $\varepsilon^2$ as a function of the dark-photon mass in the range $10\le M_{A^\prime}\le 400$ MeV. The limits cover previously unconstrained parameter space for the production of fermion or scalar DM particles $\chi$ for two benchmark models with mass ratios $M_{\chi}/M_{A^\prime}=0.6$ and $2$ and for dark fine-structure constants $0.1\le\alpha_D\le 1$.