First measurement of the muon neutrino charged current single pion production cross section on water with the T2K near detector

Abstract

TheT2Koff-axis near detector,ND280, is usedtomake thefirst differential cross sectionmeasurements of muon neutrino charged current single positive pion production on a water target at energies ∼0.8 GeV. Thedifferentialmeasurementsarepresentedasafunctionofthemuonandpionkinematics,intherestricted phase space defined by pπþ > 200 MeV=c, pμ > 200 MeV=c, cosðθπþÞ> 0.3 and cosðθμÞ> 0.3. The total flux integrated νμ charged current single positive pion production cross section on water in the restricted phase space is measured to be hσiϕ ¼ 4.25 0.48ðstatÞ 1.56ðsystÞ× 10−40 cm2=nucleon. The total cross section is consistent with the NEUT prediction (5.03 × 10−40 cm2=nucleon) and 2σ lower than the GENIE prediction (7.68 × 10−40 cm2=nucleon). The differential cross sections are in good agreement with the NEUT generator. The GENIE simulation reproduces well the shapes of the distributions, but overestimates the overall cross section normalization.