LC performance for Jet reconstruction

1. LC performance for Jet reconstruction Paola Giovannini MPPMU HEC group

2. OUTLINE • Linearity for jets respect to Calibration Hit Truth • Linearity for jets respect to Particle Jet Truth • Linearity 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 P.Giovannini, LIP ATLAS WORKSHOP

3. Validation with Cal Hits Particle Jet 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 • 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 P.Giovannini, LIP ATLAS WORKSHOP

4. Validation with Cal Hits HOW TO BUILD A TRUTH JET FROM CALIBRATION HITS Σ Truth Jet Energy after hadronic compensation (w) Calibration Hit Cluster Moment energy for every cluster in the RECONSTRUCTED jet == Truth Jet Energy due to out of cluster corrections (ooc) Out Of Cluster Calibration Hit Cluster Moment energy == Truth Jet Energy due to dead material corrections (dm) Dead Material Hit Cluster Moment energy == SEE BACK-UP FOR MORE DETAILS ON MOMENTS ALGORITHMS Truth Jet Energy after Local Hadron Calibration P.Giovannini, LIP ATLAS WORKSHOP

5. LC Jet Linearity plot Reco/Truth with Calibration hit Numerator: Jet at a defined level of correction MC Reco RATIO SHOULD BE 1 Denominator: Jet at the same defined level of correction MC Truth (Calib-Hit) AntiKt4 used as Jet Algorithm W OOC DM Jet after weighting ONLY Jet after weighting AND out of cluster Jet after weighting AND out of cluster AND dead material η bin 0.3 P.Giovannini, LIP ATLAS WORKSHOP

6. LC Jet Linearity plot Reco/Truth with Calibration hit W OOC DM W OOC DM η bin 2.1 η bin 3.2 • 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 plot Reco ONE STEP ONLY/Truth with Calibration hit RATIO SHOULD BE 1 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) AntiKt4 used as Jet Algorithm ARECO+BTRUTH+CTRUTH W OOC DM ATRUTH+BTRUTH+CTRUTH In this way the single correction performance is isolated η bin 0.3 P.Giovannini, LIP ATLAS WORKSHOP

8. LC Jet Linearity plot Reco ONE STEP ONLY/Truth with Calibration hit W OOC DM W OOC DM η bin 2.1 η bin 3.2 This approach shows that both OOC and DM corrections miss 10% of energy respect to Calibration Hit Moments, that is what LC wants to correct for P.Giovannini, LIP ATLAS WORKSHOP

9. Hit Moments Validation linearity plot Truth (CalibHit)/Truth (Particle Jet) • how much and how do • we gain at every step? • (even if we would make • LC reconstruction perfect) Numerator: Jet at a defined level of correction Calib Hits Denominator: Particle Jet W OOC DM up to 20% of the Jet energy is due to DM W OOC DM et bin 15 GeV • COMMENTS:: • non uniform response in η • most of the jet energy is deposited NEAR to • its constituents et bin 50 GeV NEED Particle ID validation to be fully reliable P.Giovannini, LIP ATLAS WORKSHOP

10. LC Jet Resolution AntiKt4 η bin 0.3 Jet at the em scale / Particle Jet Truth EM W OOC DM Jet after weighting ONLY / Particle Jet Truth Jet after weighting AND out of cluster / Particle Jet Truth Jet after weighting AND out of cluster AND dead material / Particle jet Truth DISTANCE BTW STEPS IS REDUCED:: IT IS A FAKE IMPROVEMENT DUE TO NON-LINEARITIES restoring linearity for every step P.Giovannini, LIP ATLAS WORKSHOP

11. LC Jet Resolution AntiKt4 η bin 0.3 INVERTING ORDER OF LC CORRECTIONS.. OOC applied as the last correction.. corrected for non-linear effects after washing out non linearity effects the distance between the steps is reduced but the last step is better  it’s adding “knowledge” P.Giovannini, LIP ATLAS WORKSHOP

12. LC Jet Resolution AntiKt4 η bin 0.3 INVERTING ORDER OF LC CORRECTIONS.. W applied as the last correction.. corrected for non-linear effects after washing out non linearity effects the distance between the steps is reduced but the last step is better  it’s adding “knowledge” P.Giovannini, LIP ATLAS WORKSHOP

13. LC Jet Resolution AntiKt6 η bin 0.3 using different algorithm parameter corrected for non-linear effects having a wider jet improves resolution….. P.Giovannini, LIP ATLAS WORKSHOP

14. Conclusions • 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 P.Giovannini, LIP ATLAS WORKSHOP