Measurement of inclusive ${\pi }^0$ production in the charged-current interactions of neutrinos in a 1.3-GeV wide band beam

In this paper, we report on the measurement of the rate of inclusive ${\pi }^0$ production induced by charged-current neutrino interactions in a ${\mathrm{C}}_8{\mathrm{H}}_8$ target at a mean energy of 1.3 GeV in the K2K near detector. Out of a sample of 11 606 charged-current neutrino interactions, we select 479 ${\pi }^0$ events with two reconstructed photons. We find that the cross section for the inclusive ${\pi }^0$ production relative to the charged-current quasielastic cross section is $\frac{{\sigma }_{\mathrm{CC}{\pi }^0}}{{\sigma }_{\mathrm{CCQE}}}=0.426\pm 0.032(\mathrm{stat})\pm 0.035(\mathrm{syst})$. The energy-dependent cross section ratio is also measured. The results are consistent with previous experiments for exclusive channels on different targets.

Figure 1

The energy spectrum for all muon neutrino interactions in the SciBar fiducial volume. The gray boxes correspond to the shape systematic uncertainty.

Figure 2

Schematic view of the near neutrino detector.

Figure 3

Diagram of SciBar and of the EC.

Figure 4

Charged-current total cross section divided by the neutrino energy $E_{\nu }$ for neutrino-nucleon charged-current interactions [32]. The solid line shows the calculated total cross section. The dashed, dotted, and dash-dotted lines show the calculated quasielastic, single-pion, and deep inelastic scattering, respectively. The data points are taken from the following experiments: (△) ANL [51]; (○) GGM77 [52]; (●) GGM79 [53], [59]; (*) Serpukhov [54]; (◇) ANL82 [11]; (★) BNL86 [12]; (■) CCFR90 [60]; (▾) CDHSW87 [61]; (×) IHEP-JINR96 [62]; (+) IHEP-ITEP79 [63]; (□) CCFRR84 [64]; and (▴) BNL82 [65].

Figure 5

Disconnection: distance $L_{\mathrm{disc}}$ between the reconstructed photon candidates’ conversion point and the neutrino interaction vertex.

Figure 6

Photon multiplicity of $\mathrm{CC}{\pi }^0$ candidate events.

Figure 7

Reconstructed ${\pi }^0$ mass before fit.

Figure 8

Reconstructed neutrino energy before fit.

Figure 9

${\pi }^0$ momentum distribution obtained by rescaling the Monte Carlo with the energy-independent fit result.

Figure 10

${\pi }^0\cos (\theta )$ distribution obtained by rescaling the Monte Carlo with the energy-independent fit result.

Figure 11

$\mathrm{CC}{\pi }^0$-to-CC-QE cross section ratio as a function of neutrino energy. The result of this analysis (●) is compared with our standard MC expectation and past experimental results. The previous experimental data are: (○) ANL82 [11], (□) ANL [51], (△) BNL86 [12], and (◇) $\mathrm{ANL}83+\mathrm{BNL}86$ [12, 14] (see text for details).