LC performanc

e for Jet reconstructi

onPaola Giovannini

MPPMU HEC group

P.Giovannini, LIP ATLAS WORKSHOP

2

OUTLINE

Linearity for jets respect to Calibration Hit Truth Linearity for jets respect to Particle Jet TruthLinearity for jets with only one step reconstructed (NEW) Resolution respect to Particle Jet Truth, after recovering linearity Resolution inverting the order of the calibration

for jet performance studies: 225000 di-jet events reconstructed with the new Local Hadron Calibration weights for QGSP_BERTINI (ALL STEPS!) [15.1.0]

code to produce all the plots is available in CVS as an ARA package: /offline/PhysicsAnalysis/JetPhys/JetLCPerformanceARA/JetLCPerformanceARA

06/24/09

P.Giovannini, LIP ATLAS WORKSHOP

3

Validation with Cal Hits

Particle Jet

• default reference • provided by theory

ALWAYS be final reference BUT

• does not tell us what/how ends up in the calorimeter

• no B field, no hadronic shower, no detector geometry accounted for

Calibration Hit Jet

reference for every LC step

reflects the reference used in computing the weights

on single pions tells us HOW WELL we do

what we want to do uses algorithms to attach calibration hits to a jet these algorithms need to be validated using

ParticleID to be fully reliable

06/24/09

P.Giovannini, LIP ATLAS WORKSHOP

4

Validation with Cal Hits

06/24/09

HOW TO BUILD A TRUTH JET FROM CALIBRATION HITS

for every cluster in the RECONSTRUCTED jet

Σ

Calibration Hit Cluster Moment energy

Truth Jet Energy afterhadronic compensation (w)

==

Out Of Cluster Calibration Hit Cluster Moment energy

Truth Jet Energy due toout of cluster corrections (ooc)==

Dead Material Hit Cluster Moment energy

Truth Jet Energy due todead material corrections (dm)==

Truth Jet Energy afterLocal Hadron Calibration

SEE BACK-UP FOR MORE DETAILSON MOMENTS ALGORITHMS

P.Giovannini, LIP ATLAS WORKSHOP

5

LC Jet Linearity

06/24/09

plot Reco/Truth with Calibration hit

Numerator: Jet at a defined level of correction MC Reco

Denominator: Jet at the same defined level of correction MC TruthRATIO SHOULD BE 1

Jet after weighting ONLY

Jet after weighting AND out of cluster

Jet after weighting AND out of clusterAND dead material

(Calib-Hit)

η bin 0.3

W OOCDM

AntiKt4 used as Jet Algorithm

P.Giovannini, LIP ATLAS WORKSHOP

LC Jet Linearity

6

plot Reco/Truth with Calibration hit

W OOCDM

06/24/09

η bin 2.1 η bin 3.2

W OOCDM

Few comments: weighting step seems to work for every eta bin new physics list accounted for ! out of cluster corrections are underestimated for jetEn < 300 GeV dead material corrections are underestimated for large Eta values or small jet energies

(IF CALIBRATION HITS ARE TAKEN AS TRUTH REFERENCE)

P.Giovannini, LIP ATLAS WORKSHOP

7

LC Jet Linearity

06/24/09

plot Reco ONE STEP ONLY/Truth with Calibration hit

Numerator: Jet at a defined level of correction (MC Reco for last step only + CalHit truth)

Denominator: Jet at the same defined level of correction MC Truth (CalHit)

RATIO SHOULD BE 1

η bin 0.3

W OOCDM

AntiKt4 used as Jet Algorithm

ARECO+BTRUTH+CTRUTH

ATRUTH+BTRUTH+CTRUTH

In this way the single correction performance is isolated

P.Giovannini, LIP ATLAS WORKSHOP

8

LC Jet Linearityplot Reco ONE STEP ONLY/Truth with Calibration hit

η bin 2.1 η bin 3.2

W OOCDM

W OOCDM

This approach shows that both OOC and DM correctionsmiss 10% of energy respect to Calibration Hit Moments,

that is what LC wants to correct for

06/24/09

P.Giovannini, LIP ATLAS WORKSHOP

9

Hit Moments Validation

06/24/09

linearity plot Truth (CalibHit)/Truth (Particle Jet)

et bin 15 GeV

Numerator: Jet at a defined level of correction Calib Hits

Denominator: Particle Jet

• how much and how do we gain at every step? (even if we would make LC reconstruction perfect)

W OOCDM

W OOCDM

et bin 50 GeV

up to 20% of the Jet energy is due to DM

COMMENTS::-non uniform response in η-most of the jet energy is deposited NEAR to its constituents NEED Particle ID validation to be fully reliable

P.Giovannini, LIP ATLAS WORKSHOP

10

LC Jet Resolution

06/24/09

EMW OOCDM

Jet after weighting ONLY / Particle Jet Truth

Jet after weighting AND out of cluster / Particle Jet Truth

Jet after weighting AND out of clusterAND dead material / Particle jet Truth

restoring linearityfor every step

Jet at the em scale / Particle Jet Truth

DISTANCE BTW STEPSIS REDUCED:: IT IS A FAKE

IMPROVEMENT DUE TO NON-LINEARITIES

AntiKt4η bin 0.3

P.Giovannini, LIP ATLAS WORKSHOP

11 06/24/09

LC Jet ResolutionINVERTING ORDER OF LC CORRECTIONS..

OOC applied as the last correction..

after washing out nonlinearity effects the distancebetween the steps is reducedbut the last step is better it’s adding “knowledge”

corrected for non-linear effects

AntiKt4η bin 0.3

P.Giovannini, LIP ATLAS WORKSHOP

12 06/24/09

LC Jet ResolutionINVERTING ORDER OF LC CORRECTIONS..

W applied as the last correction..

corrected for non-linear effects

after washing out nonlinearity effects the distancebetween the steps is reducedbut the last step is better it’s adding “knowledge”

AntiKt4η bin 0.3

P.Giovannini, LIP ATLAS WORKSHOP

13 06/24/09

LC Jet Resolutionusing different algorithm parameter

corrected for non-linear effects

AntiKt6η bin 0.3

having a wider jetimproves resolution…..

P.Giovannini, LIP ATLAS WORKSHOP

14

Conclusions

06/24/09

• the first set of plots show that the actual constants don’t fully compensate for the OOC and DM Hit energy included in the Moments • Calibration Hit energy accounts for most of the Jet energy, but it is not possible to say if this energy belongs to the truth Jet ParticleID() • Resolution plots taking into account non-linearity effects have been produced[ see resolution with non linear calorimeters for more details on the method !!] at every step of the LC there is a resolution improvement after washing out non-linear effects .. wider jet seems to give a better resolution for di jet events