Enhanced Reconstruction of Sub-GeV Neutrinos Charged Current Interactions in LArTPC

Abstract

This paper presents a comprehensive study of the reconstruction of sub-GeV neutrino charged-current interactions within a Liquid Argon Time Projection Chamber (LArTPC). We demonstrate that traditional charge-based calorimetry is fundamentally limited at sub-GeV scales by significant fluctuations in recombination and missing hadronic energy. We show that energy reconstruction using energy deposited as scintillation light ($L$) partially benefits from the self-compensating light effect. At neutrino energies above 400 MeV, the light-only reconstruction still outperforms charge-only methods that can separate EM and hadronic objects. The performance of the two remains comparable below 300 MeV. Using the energy-deposit information from both detector signals, we demonstrate at least 70\% efficiency can be achieved in tagging electron neutrinos and antineutrinos, respectively. By using a proximity-based algorithm coupled with a geometric lepton-exclusion cone, we also demonstrate the ability to isolate neutron-induced energy depositions from background. This enables an improvement of sub-GeV direction reconstruction by about 20 degrees for antineutrinos. This study provides new insights into how to enhance the physics reach of future LArTPC atmospheric neutrino analyses.

24 pages, 36 figures. Includ Extra study on bkg effect on direction reco, and multivariate analysis on neutrino charge separation