HadronicHadronic t-tbar selection and Jet Energy ScaleJet Energy Scale calibration

Part I : Accessing the trigger information

09/02 - Menelaos Tsiakiris

Motivation…Motivation…

Main decay modes:

di-lepton: ttbar lν lν bb 5% (e + μ)

lepton + jets: ttbar lν qq bb 30% (e + μ)

all hadronic : ttbar qq qq bb 45%

• qqbar (10%), gg (90%) ttbar

Dominant quark production mechanism

• t Wb (~100%)

• quarks (light jets)

• b quark jets (displaced vertices)

Pros:

+ Largest branching ratio

+ Kinematics that can be fully reconstructedCons:

- very large QCD multijet background challenging for the isolation of the signal

- difficulties for triggering

Tools…Tools…• Atlas offline – Athena currently on 12.0.4

• Sample 5012 (QCD) AOD di-jet sample reco. with trigger info

trig1_misal1_csc11_005012.J3_pythia_jetjet.recon.AOD.v12000402

• Sample 5200 (ttbar) AOD semi-leptonic sample reco. with trigger info

trig1_misal1_csc11_005200.T1_McAtNlo_Jimmy.recon.AOD.v12000402

• UserAnalysis (00-08-43) package very basic stuff…

• Trigger Decision Class (by M.Wielers) access the trigger information

List of predefined trigger menus in release 12 :

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

Contains the trigger menu items as defined at reconstruction.

Trigger Menu : 12.0.4 official production CSC-03

About Trigger Decision …About Trigger Decision …

• Obtains the trigger decision for each event• Gives the list of signatures running in each trigger level

• Implemented from 11.0.5 - fully functional on 12.0.x

• From 12.0.4 also included in AODs

TriggerDecisionMakerTriggerDecisionMaker Algorithm runs after the trigger steering

determines which HLT or LVL1 items were satisfied

fills the TriggerDecision object

TriggerDecision class User Interface:

…bool isDefined(“L1_2J45”)bool isTriggered(“L1_2J45”)bool isTriggerPassed()void print()void printAccepted()…

Starting point:

Wiki page: https://twiki.cern.ch/twiki/bin/view/Atlas/TriggerDecision

Browse code @ CVSView and documentation @ Doxygen

Methods…

More on Trigger Decision… How-to useMore on Trigger Decision… How-to use::i) Include the Trigger, in the cmt/requirementcmt/requirement

use TrigSteeringEvent TrigSteeringEvent-* Trigger/TrigEvent

ii) Edit AnalysisSkeleton.cxxAnalysisSkeleton.cxx

#include "TrigSteeringEvent/TriggerDecision.h"

iii) Retrieve the trigger decision from StoreGateStoreGate /** Get Trigger Decision */ const TriggerDecision* trigDec = 0; StatusCode sc = m_storeGate->retrieve( trigDec, MyTriggerDecisionMyTriggerDecision); if( sc.isFailure() || !trigDec) { mLog << MSG::WARNING << "No Trigger Decision found in TDS" << endreq; return StatusCode::SUCCESS; }

Need more insight? https://twiki.cern.ch/twiki/bin/view/Atlas/TriggerAnalysisTutorial

!!!

This is only for handling the MSG service

trigDec->isTriggered(“L1_J35”)

Returns true/false

Default key

In case you re-run the trigger hypothesis on an ESD/AOD

MyTriggerDecision++

e.g

Reco container

Trigger Decision

if (accepted)

Fill accepted_histoaccepted_histo

Truth container

findAMatch

Fill highest_truth_histohighest_truth_histo

Divide

Find highest energetic jet

Turn – on curveTurn – on curve : :

For a trigger request of: E > 50 GeV

The percentage of jets that pass the energy threshold with respect to their true energy

E truth

My My analysisanalysis::

Per event…

Ideal…

The jet160jet160 item turn-on curves (5012):

LVL1: L1_J45 (20GeV)LVL2: L2_ jet160 EF: EF_jet160

!!!

!!!

!!!

“garbage” at low energies !?!?

Reco container

Trigger Decision

if (accepted)

Fill accepted_histoaccepted_histo

Truth container

findAMatch

Fill highest_truth_histohighest_truth_histo

Divide

Find highest energetic jet

Offline reconstruction algorithm Trigger Reco

ContainerTrigger reconstruction algorithm

Fast solution…

Truth container

Find highest energetic jet

Trigger Decision

if (accepted)

Divide

Fill highest_truth_histohighest_truth_histo

Fill accepted_histoaccepted_histo

The jet160jet160 item turn-on curves (5012):

The “garbage” are gone… !

But for this sample the jet160 item is not good …. Very few events next slide

The jet160jet160 item (5012):

Truth distribution

Only very few events above 180 GeV

The 2jet1202jet120 item (5012):

LVL1: L1_2J45LVL2: L2_ jet120L2_jet120 EF: EF_jet120EF_jet120

Note the naming convention for L2 and EF!

Still few statistics

based

New sample 5200. Semi-leptonic ttbar… … just looked at it a few days ago

… very few events after 220 GeV !

Truth distribution

The jet160 item on a 5200 sample , 4000 events:

90 – 100%

Starts building up after 160 GeV

Bit sloppy here… ~ 80% -100%

AnalysisSkeleton INFO The L1 J45 : 3987 ~100%AnalysisSkeleton INFO The L2 jet160 : 2281 57%AnalysisSkeleton INFO The EF jet160 : 421 11%

The 2jet120 item (5200) 4000 events:

~ 80% - 90%

~ 50% - 60%

Starts to build up only after 120 GeV

AnalysisSkeleton INFO The L1 2J45 : 3859 96%AnalysisSkeleton INFO The L2 2jet120 : 1930 48%AnalysisSkeleton INFO The EF 2jet120 : 278 7%

The 3jet65 item (5200) 4000 events:

LVL1: L1_3J45LVL2: L2_ jet65L2_jet65L2_jet65 EF: EF_jet65EF_jet65EF_jet65

~ 80% - 90%

~ hardly 40 - 50%Again…

AnalysisSkeleton INFO The L1 3J45 : 3434 85%AnalysisSkeleton INFO The L2 3jet65 : 2508 63%AnalysisSkeleton INFO The EF 3jet65 : 522 13%

~ 90% !

The 4jet50 item (5200) 4000 events:

LVL1: L1_4J45LVL2: L2_ jet50L2_jet50L2_jet50L2_jet50

EF: EF_jet50EF_jet50EF_jet50EF_jet50AnalysisSkeleton INFO The L1 2J45 : 2392 60%AnalysisSkeleton INFO The L2 2jet120 : 1771 44%AnalysisSkeleton INFO The EF 2jet120 : 406 10 %

No more than 40%

~ 60% - 70%~ 70 % !!!

again3987 passed LVL1 : 99%

3137 passed LVL2 : 78%

857 passed EF : 21%

Total accepted events:

About Jet Energy Scale…About Jet Energy Scale…• The efficiency of the jet triggers depends heavily on the quality of the Jet Energy Scale calibrations in the online system.

For the di-jet 5012 sample

• As an introduction to this study I looked on the JES based on offline reconstruction

JESJES :

Fitting each bin of the x-axis with a gaussian and plotting the Constant(height) , Mean and Sigma

Offset of 2 GeV

The distribution is getting wider for high energies (less events ?)

50125012 di-jet sample di-jet sample

About Jet Energy Scale…About Jet Energy Scale…

For the ttbar 5200 sample

JESJES : 5200 ttbar sample

Not the same as 5012 !

My to-do list …My to-do list …

• Run the online reconstruction algorithm. (Samples ??)

• Do the turn-on curves based on the trigger reco. algorithm and improve diagrams (e.g. errors)

• Examine JES for the online case

• Look into EventView Trigger packagehttps://twiki.cern.ch/twiki/bin/view/Atlas/EventViewTrigger

THANK YOU!THANK YOU!