Study of pion production in $ν_μ$ interactions on $^{40}$Ar in DUNE using GENIE and NuWro event generators

Abstract

The study of pion production and the effects of final state interactions (FSI) are important for data analysis in all neutrino experiments. For energies at which current neutrino experiments are being operated, a significant contribution to pion production is made by resonance production process. After its production, if a pion is absorbed in the nuclear matter, the event may become indistinguishable from quasi-elastic scattering process and acts as a background. The estimation of this background is very essential for oscillation experiments and requires good theoretical models for both pion production at primary vertex and after FSI. Due to FSI, the number of final state pions is significantly different from the number produced at primary vertex. As the neutrino detectors can observe only the final state particles, the correct information about the particles produced at the primary vertex is overshadowed by FSI. To overcome this difficulty, a good knowledge of FSI is required which may be provided by theoretical models incorporated in Monte Carlo (MC) neutrino event generators. In this work, we will present simulated events for two different MC generators - GENIE and NuWro, for pion production in $ν_μ$CC interactions on $^{40}$Ar target in DUNE experimental set up. A brief outline of theoretical models used by generators is presented. The results of pion production are presented in the form of tables showing the occupancy of primary and final state pion topologies with 100$\%$ detector resolution and with kinetic energy detector threshold cuts. We observe that NuWro (v-19.02.2) is more transparent (less responsive) to absorption and charge exchange processes as compared to GENIE (v-3.00.06), pions are more likely to be absorbed than created during their intranuclear transport and there is need to improve detector technology to improve the detector threshold for better results.