Mainz 2004 – scientific programme

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T: Teilchenphysik

T 306: Trigger und DAQ III

T 306.4: Talk

Tuesday, March 30, 2004, 16:45–17:00, HS VII

Impact of a b-jet trigger on searches for tt-resonances and heavy Higgs bosons at ATLAS — •Anca Purcărea, Peter Mättig, and Jenny Böhme — Bergische Universität Wuppertal, Fachbereich Physik, Gaußstr. 20, 42097 Wuppertal

At LHC, at low luminosity, per year and per experiment about 8 million top quark pairs will be produced. The final states of fully hadronic tt-events consists of at least six jets (including two b-jets). A trigger decision has to be based on this jet information.

Due to high E_T thresholds, the trigger efficiency for fully hadronic tt-events is only at the order of 20%. This efficiency could be increased by detecting two bottom jets at the LVL2 trigger, allowing to lower the energy threshold while maintaining a large rejection of QCD background events.

If b-jet identification will be available at LVL2, QCD background could be suppressed effectively. This would allow for lowering the trigger E_T thresholds and thereby increasing the trigger efficiency for tt-events.

As an example the impact of introducing b-tagging into the trigger system on the discovery of tt-resonances and heavy Higgs bosons via the decay H→ tt is discussed. Special attention is paid to the improvement of the discovery prospects by lowering the E_T thresholds of the actual jet trigger menu.