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Draft: [QEE] Remove low-mass events from Z->ll lines

Luke Grazette requested to merge lugrazet-ew-Zcutcomposite into qee_upgrade

Context

There's 'leakage' below 40 GeV making it's way into Hlt2/Sprucing.
This is always cut away anyway offline so we might as well remove it.

image

We believe it's due to the distinction between `CombinationCut` and `CompositeCut` in the ParticleCombiners. `Combination Cut` = before vertex fit, `CompositeCut` = after vertex fit. So the way the combiners are currently set up, it's possible that there's events that pass the CombinationCut of M>40 GeV, but the events post-vertex-fit have a much lower Mass (as small as 5 GeV).

It's been suggested that these are muons from different PVs (we don't include a vertex requirement).

Effect on Rate/BW

Expected to be small, visually per-cent level of the events being selected by the Zmumu line fit into this category, and it's already relatively low rate

ToDo

  • Local BW Test
Edited by Luke Grazette

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