Improved measurement of neutral current coherent ${\pi }^0$ production on carbon in a few-GeV neutrino beam

The SciBooNE Collaboration reports a measurement of neutral current coherent ${\pi }^0$ production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive ${\pi }^0$ production has been improved by detecting recoil protons from resonant ${\pi }^0$ production. We measure the ratio of the neutral current coherent ${\pi }^0$ production to total charged current cross sections to be $(1.16\pm 0.24)\times {10}^{-2}$. The ratio of charged current coherent ${\pi }^{+}$ to neutral current coherent ${\pi }^0$ production is calculated to be ${0.14}_{-0.28}^{+0.30}$, using our published charged current coherent pion measurement.

Figure 1

Vertex activity after all event selections: the contribution from NC coherent ${\pi }^0$, incoherent NC ${\pi }^0$ with recoil neutrons, incoherent NC ${\pi }^0$ with recoil protons, internal backgrounds with a ${\pi }^0$ in the final state, internal background without a ${\pi }^0$ in the final state and “dirt” background events are shown separately for the MC simulation.

Figure 2

The $E_{{\pi }^0}^{\mathrm{rec}}(1-\cos {\theta }_{{\pi }^0}^{\mathrm{rec}})$ distributions after fitting with (top) and without (bottom) vertex activity.

Figure 3

The contours corresponding to 68%, 90%, and 99% confidence level for the fitted values of the scaling parameters; the number of degrees of freedom is 2.

Figure 4

Reconstructed ${\pi }^0$ momentum distributions after fitting with the vertex activity (top) and without vertex activity (bottom).

Figure 5

The $\cos {\theta }_{{\pi }^0}^{\mathrm{rec}}$ distributions after fitting with the vertex activity (top) and without vertex activity (bottom).