Trigger Menus

Invisible Higgs input to trigger menus for initial running

4/9/2007Invisible Higgs CSC Note meeting

Ricardo Goncalo, RHUL

4 Sep.07 Invisible Higgs CSC note 2

Question A)

• There is a proposed Trigger menu for 1031 which can be found at

https://twiki.cern.ch/twiki/bin/view/Atlas/TriggerPhysicsMenu

A) We ask that you review this menu's suitability for the physics and performance issues relevant to your group. What is missing? What is the motivation for the desired triggers? Are there triggers that may not be needed, or for which a larger prescaling could be applied if the overall rate is too large? Which triggers are critical for measuring trigger and reconstruction efficiencies and background rejections.

4 Sep.07 Invisible Higgs CSC note 3

Question B)

B) What calibration/alignment triggers are needed [to be run concurrently with normal data taking runs]? How many events are needed and what kind of accuracy can you expect as a function of the assumed rate? Can you quantify the impact of a reduced rate on accuracy? [Note that: in some cases, a calibration trigger may be given special treatment in the TDAQ system so that only a subset of the detectors and/or only regions of interest are read out].

4 Sep.07 Invisible Higgs CSC note 4

Question C)

C) What triggers are absolutely "unprescalable" and why?

4 Sep.07 Invisible Higgs CSC note 5

Question D)

D) What triggers MUST go into the express stream? What will you do with the express stream data sets? What is the impact if it goes only into the regular stream? [Note: The events in the Express stream are complete events and contain a subset of the events sent to regular stream. Its purpose is to obtain rapid feedback, such as needed for Tier0 monitoring. Hence the question is what needs to be processed in a fast time-scale that can only be accomplished with your trigger in the express stream?]

4 Sep.07 Invisible Higgs CSC note 6

Question E)

E) It can be difficult to estimate some rates, therefore what would you do if some trigger rates are higher than expected by a factors of 2, 5 or 10? Identify the triggers that are candidates for higher thresholds or prescales. Inversely, which triggers are candidates for lower thresholds or smaller prescales if the rates are half of the expected value?

4 Sep.07 Invisible Higgs CSC note 7

Question F)

F) We are starting to consider the 10**32 menu. New unprescaled triggers will be added at higher thresholds, presecales on 10**31 triggers increased and perhaps some triggers dropped. We would like your preliminary thoughts on this.

4 Sep.07 Invisible Higgs CSC note 8

VBF channel

• Forward jets needed!• Forward jets + ETmiss to reduce rates• ETmiss trigger alone may cut too hard at 1031

(currently highest threshold at ~50GeV)

4 Sep.07 Invisible Higgs CSC note 9

Example from Guilherme’s thesis

4 Sep.07 Invisible Higgs CSC note 10

ZH channel

• Lepton/di-lepton trigger obvious• Missing ET trigger threshold probably too soft when we get to 1031

• Lepton+ETmiss worth looking into

4 Sep.07 Invisible Higgs CSC note 11

higher efficiency was found in the meantime

4 Sep.07 Invisible Higgs CSC note 12

Preliminary analysis: cutsReference analysis cuts:• Leptons:

– 1 electron (pT>25GeV; ||<2.5)or 1 muon (pT>20GeV; ||<2.5)– Veto on additional electron (pT>10GeV)or additional muon (pT>6GeV)

• Jets:– 2 b-tagged jets– 2 or more un-tagged jets

• tbjj reconstruction: – |mjj-mW|<15GeV; ||<2.0 for jets in Wjj– |mbjj-mt|<25GeV

• tbl reconstruction:– mT > 120 GeV (using lepton and full ET

miss to calculate mT)• Other:

– Missing ET > 150GeV Raised to 220GeV after optimisation– Scalar sum of pT of reconstructed l j j b b: ET>250GeV– In reconstructed W jj: Rjj =(2

jj+2jj) < 2.2 (to reject lep-tau decays)

Single-lepton trigger – follow closely what top trigger is doing

ETmiss or ETmiss + lepton may be worth trying

4 Sep.07 Invisible Higgs CSC note 13

Next steps

• Go over questions from Srini

• For invisible Higgs these just give a vague idea of what out trigger will really be like

• If we’re making hard choices, may be better to do them early– How many times can the analyses be tuned?