# Double Neutrino

For this study, the double neutrino algorithm is being validated against the reference implementation using varying levels of Monte Carlo truth. Similar to the single neutrino reconstruction, the aim is to assert whether the custom implementation is consistent and how well it reconstructs the neutrino pairs. Starting with the simplest case, the truth children b-parton and lepton pairs are given to the algorithm to compare the resultant kinematics to the true neutrinos. This is followed by the replacement of the b-parton with matched truth jets and detector jets. Finally, only detector objects will be used to perform the reconstruction, this includes matched detector jets and leptons.

As an additional ad-hoc study, the original reference algorithm triggers a secondary optimization step, if no ellipse intersection solutions were found. This involves rotating the solutions in a way which minimizes the missing energy difference given by the neutrino three vectors and detector observations. In the standard pyc reimplementation, such secondary optimization is not performed and could result in less solution statistics compared to the reference. To validate pyc, events with no secondary optimization are compared using the reconstructed top-quark mass, as shown in figure collections 5.

## Selection Criteria

Events are required to have exactly two leptonically decaying top-quarks on truth children level. For subsequent studies involving truth jets and detector based objects, both b-quarks and leptons on truth children level need to be matched accordingly. If any of these conditions are not satisfied, the respective part of the study is skipped for the event. Furthermore, truth jets and jets are required to have only single top contributions, otherwise the event is vetoed.

## Particle Definitions

Leptons and neutrinos are defined as:

electrons

muons

taus