Four Momentum Transfer Discrepancy in the Charged Current $π^+$ Production in the MiniBooNE: Data vs. Theory
The MiniBooNE experiment has collected what is currently the world's largest sample of neutrino muon charged current single charged pion interactions, roughly 46,000 events. The purity of the CC1pi+ sample is 87% making this the purest event sample observed in the MiniBooNE detector. The average energy of neutrinos producing CC1pi+ 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 CC1pi+ 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 [Kuzmin et al. and Berger and Sehgal] and coherent production. Using calculations from Graczyk and Sobczyk paper, an updated form for the vector form factor [Lalakulich et al.] has also been adopted. The results of this improved description of CC1pi+ production will be compared to the high statistics MiniBooNE CC1pi+ data and several existing parametrisations of the axial vector form factor.