Measurement of muon neutrino induced charged current interactions without charged pions in the final state using a new T2K off-axis near detector WAGASCI-BabyMIND

Abstract: We report a flux-integrated cross section measurement of muon neutrino interactions on water and hydrocarbon via charged current reactions without charged pions in the final state with the WAGASCI-BabyMIND detector which was installed in the T2K near detector hall in 2018. The detector is located 1.5$^\circ$ off-axis and is exposed to a more energetic neutrino flux than ND280, another T2K near detector, which is located at a different off-axis position. The total flux-integrated cross section is measured to be $1.26 \pm 0.18\,(stat.+syst.) \times 10^{-39} $ $\mathrm{cm^{2}/nucleon}$ on CH and $1.44 \pm 0.21\,(stat.+syst.) \times 10^{-39} $ $\mathrm{cm^{2}/nucleon}$ on H$_{2}$O. These results are compared to model predictions provided by the NEUT v5.3.2 and GENIE v2.8.0 MC generators and the measurements are compatible with these models. Differential cross sections in muon momentum and cosine of the muon scattering angle are also reported. This is the first such measurement reported with the WAGASCI-BabyMIND detector and utilizes the 2020 and 2021 datasets.