Measurement of charged kaon production by neutrinos at MINERvA

Charged kaon production by atmospheric neutrinos is a background in searches for the proton decay $p \rightarrow K^{+} \bar{\nu}$. This channel is well motivated theoretically, and is favored by Supersymmetric Grand Unified Theories. Measurements of neutrino-induced $K^{+}$ production are important inputs for current and future proton decay searches at Super-K, Hyper-K and DUNE. The MINERvA neutrino-nucleus cross section experiment at Fermilab uses timing information to reconstruct $K^{+}$ decay-at-rest events. Differential cross section measurements are presented for both charged- and neutral-current neutrino interactions on plastic scintillator (CH). The cross section in $K^{+}$ kinetic energy, $d\sigma/dT_K$, is observed to be relatively flat between 0 and 500 MeV for both charged- and neutral-current scattering. Its shape is in good agreement with the prediction by the GENIE neutrino event generator when final-state interactions are included. A measurement of the hadronic visible energy in neutral-current $K^{+}$ events is also presented, as proton decay backgrounds come from events with very low visible energy. The spectrum is observed to be slightly softer in data than in \genie. A search for charged-current coherent $K^{+}$ production, $\nu_{\mu}A\rightarrow\mu^{-}K^{+}A$, is also presented. This rare process brings a $K^{+}$ on shell and leaves the target nucleus in its ground state. We find the first experimental evidence for the process at $3\sigma$ significance.