Triggering for SUSY Higgs

Motivation

While the discovery of the Standard Model (SM) Higgs at the LHC may take significant amount of data to accomplish, an intriguing possibility is that the existence of new physics such as Supersymmetry predicts additional Higgs bosons which may even be discovered earlier than the lowest mass SM like Higgs boson h0. In the Minimal Supersymmetric Standard Model (MSSM), a significant range of parameter space with large tanb would result in a much enhanced production rate of the heavier SUSY Higgs H0/A0 through the associated production of bbH0/A0 and the only significant decay modes are H0/A0→  bb or tt. The wide open range of tanb values allowed also made the searches in these modes a active hot topic at the Tevatron (a review of current status can be found in this Lepton-photon talk). However, the background at the LHC is expected to be considerably worse than at the Tevatron so that the triggering strategy becomes critical to preserve this opportunity for discovery.  This project is related to the triggering strategy study for the H0/A0 decays to bb. For the level-1 trigger, the configuration of multi-jet trigger thresholds is crucial make the initial save of these events and would heavily influence the sensitive mass range for H0/A0 and the tolerable range for the L1 trigger rate. The Level-2 software trigger will need to make fast decisions to reject background based on the tagging of b quarks in these events.     

Project Tasks

Evaluate the Level-2 b-tagging trigger functional and CPU performance and investigate possible improvements of the tracking algorithm. This involves running ATLAS trigger slice analysis software on signal Monte Carlo events and background multi jet events to evaluate performance. Note that the general tracking performance and b-tagging studies are also related to the both the projects on SUSY events with displaced vertices and the L2 b-tag algorithm study in the Jet/MET/b-tag Analysis group.

The actual software work require some prior knowledge of Object-Oriented  programming with C++. There will be a significant learning curve associated with getting familiarized with the ATLAS software framework, although there are web based instructions in the ATLAS workbook for general ATLAS computing and various trigger software tutorials to help the process. The analysis part of the work will involve the use of ROOT, for which some prior knowledge would be advantageous but it is not a requirement. The actual  tasks may involve e.g. generating Monte Carlo signal samples, rerunning trigger simulation with modified configurations to examine effects on signal and background samples for the physics performance study. For the software CPU performance aspects, specific timing measurements will be needed to diagnose the sources of the major CPU consumption.       

Su Dong


Last modified: Fri Sep 14 22:11:39 PDT 2007