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
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