Home E-mail Notes Meetings Search

[ Home | Contents | Search | Start a new article | Reply | Next | Previous | Up ]


thoughts on the trigger efficiencies

From:
Date: 12/10/97
Time: 8:46:51 AM
Remote Name: 137.138.115.189

Comments

Dear Trigger and Physics fans, A discussion with Guy triggered me to make some thoughts on the definition of the trigger efficiency. Let me make a very exact definition which follows here. Of course this definition is not something new, but I just try to be very precise. We consider the following three exclusive decay modes: 1)Bd -> J/phi(->mu mu) K_s(->pi pi) mainly for muon trigger 2)Bd -> J/psi(->e e) K_s(->pi pi) mainly for e trigger 3)Bd -> pi pi two high Pt hadron 4)Bs -> Ds(->K K pi) pi one high Pt hadron 5)Bd -> D(->K pi) K*(-> K pi) no high Pt hadron For decay modes 1, 2, 3, and 4, we first obtain smaple of events where the exclusive states are offline reconstructed, tagged by the offline tagging routine and corectly tagged, say N such events. We now apply triggers, i.e. muon, electron or hadron to this sample. The trigger efficiency is then the numbber of triggered events devided by N. In this definition, the trigger efficiency is for "truely" useful events at the moment of the TP analysis. For decay mode 5, we do not need apply tag. In this way, we have uneqely defined trigger efficencies which demonstrate "usefulness" in a simple way for five different decay modes. They can be used for our famous minimum bias retention versus trigger efficiency figures. Drawbacks for this definition are, 1)offline recontruction and tagging work must be finished before having the final trigger performance figures and 2)trigger performance is somewhat restricted by the knowledge of reconstruction at the Technical Proposal.

The purpose of this e-mail is just to provoke discussions. I hope that people express their ideas. yours Tatsuya