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

TL;DR

This study explores improved methods for reconstructing sub-GeV neutrino interactions in LArTPCs, highlighting the advantages of scintillation light energy measurements and advanced algorithms for particle separation and direction reconstruction.

Contribution

The paper introduces a combined energy-deposit approach and novel algorithms that enhance neutrino flavor separation and direction reconstruction at sub-GeV energies.

Findings

Light-only energy reconstruction outperforms charge-only above 400 MeV.

70% efficiency in separating electron neutrinos and antineutrinos.

Improved direction reconstruction by about 20 degrees for antineutrinos.

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 recombination fluctuations and missing hadronic energy. We show that energy reconstruction using energy deposited as scintillation light (L) partially benefits from the previously reported 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 a 70% efficiency in separating electron neutrinos and antineutrinos. 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.