...

High Level Trigger b-tagging

Tagging b-jets at the trigger level can expand the physics reach of ATLAS in many ways: it allows to lower the jet ET threshold to increase the acceptance of interesting physics events containing
multiple b-jets (like bbH and ttH ), and can be used to reduce non-b backgrounds and improve the purity of Super-symmetry searches involving b-jets in the ?nal state.

The SLAC group has implemented one of the two ATLAS b-tagging algorithms at level 2 trigger: the Impact Parameter ?2 Probability tagger (IPChi2)

Current and future work involves the optimization of the operational parameters of the algorithm, determination of performance in real data events, and the investigation of new trigger menus involving b-quarks and missing transverse energy for Super-symmetry searches.

LVL2 impact parameter Chi2 algorithm

The IPChi2 tagger is based on the impact parameter distribution of mis-tags, which can be derived directly from data and does not require the use of Monte Carlo templates as in the likelihood ratio b-tagger.

...

b+MET combined trigger

—

Test