Reconstructing the Mass of Heavy Neutral Leptons in Neutrino Experiments

Recent research has focused on the mass reconstruction of heavy neutral leptons (HNLs) produced in meson decays, specifically within the context of the ICARUS experiment at Fermilab. The study, titled "Mass Reconstruction of Heavy Neutral Leptons from Stopped Mesons," authored by Gustavo F. S. Alves, P. S. Bhupal Dev, Kevin J. Kelly, and Pedro A. N. Machado, explores how HNLs can be efficiently produced in short- to medium-baseline accelerator neutrino experiments. The researchers highlight that HNLs can leave detectable signals through their decays inside neutrino detectors.

The authors demonstrate that the ICARUS experiment is capable of reconstructing the mass of HNLs and exploring new parameter space within the mass range of 70-190 MeV. This reconstruction relies on two main factors: the simple two-body kinematics of HNL production from stopped kaon decays at the NuMI absorber and the high resolution of Liquid Argon Time Projection Chamber (LArTPC) detectors in reconstructing final state particles.

The mass reconstruction method presented is noted for its robustness, even under realistic energy resolution and angular smearing of charged leptons, making it applicable to any LArTPC detector. The study also discusses potential synergies between the ICARUS experiment and future facilities, such as the DUNE near detector and PIP-II beam dump, in probing the HNL parameter space further.

These findings are significant as they could enhance the understanding of neutrino physics and the role of heavy neutral leptons in the broader context of particle physics. The research contributes to ongoing efforts to explore new physics beyond the Standard Model, which could have implications for understanding the fundamental nature of matter and the universe.

The full paper can be accessed at arXiv:2409.04394.