First Measurement of Charged-Current Muon-Neutrino-Induced K^{+} Production on Argon Using the MicroBooNE Detector

The MicroBooNE experiment is an 85 tonne active mass liquid argon time projection chamber neutrino detector exposed to the on-axis Booster Neutrino Beam at Fermilab. One of MicroBooNE's physics goals is the precise measurement of neutrino interactions on argon in the 1 GeV energy regime. Building on the capabilities of the MicroBooNE detector, this analysis identifies K^{+} mesons, a key signature for the study of strange particle production in neutrino interactions. This measurement is furthermore valuable for background estimation for future nucleon decay searches and for improved reconstruction and particle identification capabilities in experiments such as the Deep Underground Neutrino Experiment. In this Letter, we present the first-ever measurement of a flux-integrated cross section for charged-current muon neutrino induced K^{+} production on argon nuclei, determined to be 7.93±3.22(stat)±2.83(syst)×10^{-42}  cm^{2}/nucleon based on an analysis of 6.88×10^{20} protons on target. This result was found to be consistent with model predictions from different neutrino event generators within the reported uncertainties.