Four Momentum Transfer Discrepancy in the Charged Current πplus; Production in the MiniBooNE: Data vs. Theory

The MiniBooNE experiment has collected what is currently the world's largest sample of vμ charged current single charged pion (CC1π+) interactions, roughly 46,000 events. The purity of the (CC1π+) sample is 87% making this the purest event sample observed in the MiniBooNE detector. The average energy of neutrinos producing (CC1π+) interactions in MiniBooNE is about 1 GeV, therefore the study of these events can provide insight into both resonant and coherent pion production processes. In this talk, we will discuss the long-standing discrepancy in four-momentum transfer observed between (CC1π+) data and existing predictions. Several attempts to address this problem will be presented. Specifically, the Rein-Sehgal model has been extended to include muon mass terms for both resonant and coherent production. Using calculations from [8], an updated form for the vector form factor has also been adopted. The results of this improved description of (CC1π+) production will be compared to the high statistics MiniBooNE (CC1π+) data and several existing parametrisations of the axial vector form factor.