First measurement of the ${\nu }_{\mu }$ charged-current cross section on a water target without pions in the final state

This paper reports the first differential measurement of the charged-current interaction cross section of ${\nu }_{\mu }$ on water with no pions in the final state. This flux-averaged measurement has been made using the T2K experiment’s off-axis near detector, and is reported in doubly differential bins of muon momentum and angle. The flux-averaged total cross section in a restricted region of phase space was found to be $\sigma =(0.95\pm 0.08(\text{stat})\pm 0.06(\text{det syst})\pm 0.04(\text{model syst})\pm 0.08(\text{flux}))\times {10}^{-38}{\mathrm{cm}}^2/\mathrm{n}$.

Figure 1

An exploded view of T2K’s off-axis near detector.

Figure 2

A schematic of the PØD, showing the structure of the layers. The beam travels from the left to the right. The red box outlines the approximate fiducial volume used for this analysis.

Figure 3

Data and MC distributions of the water-in $\mathrm{CC}0\pi$ signal selection. neut 5.3.2 MC has been normalized to data POT and is sorted into various truth topologies.

Figure 4

Data and MC distributions of the water-in $\mathrm{CC}1{\pi }^{+}$ sideband selection. neut 5.3.2 MC has been normalized to data POT and is sorted into various truth topologies.

Figure 5

Data and MC distributions of the water-in CCOther sideband selection. neut 5.3.2 MC has been normalized to data POT and is sorted into various truth topologies.

Figure 6

The double differential ${\nu }_{\mu }$ $\mathrm{CC}0\pi$ cross section on water for each slice in $\cos {\theta }_{\mu }$.

Figure 7

The fractional error from each source of uncertainty on the double differential ${\nu }_{\mu }$ $\mathrm{CC}0\pi$ cross section on water.

Figure 8

Here, the $\mathrm{CC}0\pi$ water cross section from the PØD is overlaid with the $\mathrm{CC}0\pi$ ${\mathrm{C}}_8{\mathrm{H}}_8$ cross section previously measured by T2K [9]. The error bars shown include all sources of uncertainty except the flux. In regions where $\cos {\theta }_{\mu }$ slices are different between the water and hydrocarbon result, the bin edges are noted in the legend.

Figure 9

A comparison of the $\mathrm{CC}0\pi$ water cross section against two Martini model predictions on carbon, one with 2p2h contributions and one without.

Figure 10

A comparison of the $\mathrm{CC}0\pi$ water cross section against the SuSAv2 model. Predictions for CCQE and 2p2h on oxygen are shown separately along with their sums and average over the bins.