Btag the jet: run b-tagging NNs without the BTagging object
Sometimes it would be pretty useful to use the b-tagging neural networks without a
BTagging object. This MR modifies
DL2Tool to add a
decorate(xAOD::Jet&) method, which reads and writes auxdata to the
Jet object, without requiring
BTagging. The standard way to b-tag jets remains the same: the information is all added to the
BTagging object via
So far this method isn't being used anywhere, and this addition should not change any outputs. We'd nonetheless like it to support two related applications in (b-)jet trigger:
- ATR-24308: Using tracks associated to jets to estimate the primary vertex position for that jet. With the jet vertex position we should be able to reject events where some of the leading jets are pileup, using only ROI-based tracking. Since this isn't really a b-tagging application, we should probably add any related decorations to the jet.
- We're also investigating ROI tracking for fast b-tagging. Whether the discriminant is stored on the
BTaggingobject or the
Jetobject is something that we'll discuss with the jet trigger group in the coming weeks. There may be an advantage to storing on the
Jetto avoid creating too many instances of
BTagging(the standard b-tagging in the trigger must create a
BTaggingobject, but runs later in the chain).