CLD fullsim for FCCee: muon->pion misidentification at 2-7 GeV using PandoraPF

Dear all,

I am working on tau reconstruction using full simulated samples with CLD, starting from Pandora PFOs.

I have noticed a sizeable contamination of muons in my analysis: these are muons originating from tau decays which are identified as pions by Pandora, concentrated between 2 and 7 GeV and at central Theta. This is using the "PandoraPFOs" sample (image attached) , and I see a similar tendency with "TightSelectedPandoraPFOs". Note in the image there are also muons below 2 GeV and a small leakage at high momentum at Theta=pi/2: those are not an issue.

@Zehvogel pointed me to a difference in muon algorithm starting at 7 GeV, which should explains this behaviour:

https://github.com/PandoraPFA/LCContent/blob/master/src/LCPlugins/LCParticleIdPlugins.cc#L434 (LCMuonId)
https://github.com/PandoraPFA/LCContent/blob/master/src/LCParticleId/MuonReconstructionAlgorithm.cc

Is there an easy way to tune the settings of the Muon ID in Pandora, eg changing the threshold to start at 5 GeV ? If there is any documentation about how to tune this I can do a check.

Alternatively, any further tweaks on how to improve the muon ID at low momentum would be great.

More plots are on the way (requested by @BrieucF ), I will update the ticket as soon as they are ready.

Regards,

María Cepeda

Start with LCContent/src/LCPlugins/LCParticleIdPlugins.cc at the LCMuonId reference and LCContent/src/LCParticleId/MuonReconstructionAlgorithm.cc to understand the 7 GeV behavior. Check whether CLDConfig exposes settings for tuning this threshold, then validate any change against the reported 2–7 GeV muon-to-pion contamination and the additional plots requested in the thread.