Bibhuti Parida

TIFR, Mumbai

04/08/2012 1

Jet reconstruction studies using Z+ jet data at CMS

India-CMS Meeting, BARC 03-04 August 2012

Exploit the balance of the transverse momentum of Z boson and accompanying one highest Pt Jet

Distributions of muon, Z-boson and Jet kinematics are ploted

Analyze of 𝑃𝑡(𝑍)

𝑃𝑡(𝐽𝑒𝑡) ratios with different Pt(Z) bins for Calo

Jet, JPT Jet and Pf Jet Jet resolution plots in bins of Pt(Z) are shown Jet Selection efficiency in bins of Pt(Z) are shown

Motivations:

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Dataset, Global tag and CMSSW used Dataset: /DoubleMu/Run2011A-May10ReReco-v1/AOD

/DoubleMu/Run2011A-PromptReco-v4/AOD

/DoubleMu/Run2011A-PromptReco-v6/AOD

Global Tag : GR_R_42_V23 CMSSW: CMSSW_4_2_5 & CMSSW_4_2_8

Corrections:

a. L1Offset, L2Relative and L3Absolute corrections are applied for Calo Jet and JPT Jets.

b. L1FastJet, L2Relative and L3Absolute corrections are applied for Particle Flow (PF) Jets.

c. L2L3 Residual correction applied

Trigger :

HLT_DoubleMu7_v1, HLT_DoubleMu7_v2, HLT_Mu13_Mu8_v2, HLT_Mu13_Mu8_v3, HLT_Mu13_Mu8_v4, HLT_Mu13_Mu8_v6, HLT_Mu13_Mu8_v7

JSON: Cert_160404-180252_7TeV_PromptReco_Collisions11_JSON_MuonPhys.txt

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Selection criteria used: Reconstruction of Z boson

Transverse momentum of muons (Pt > 20 GeV/c)

Global track-fit chi square for muons < 10

Muon d0 < 0.2 mm (transverse IP w.r.t. beamspot)

Tracker Isolation per muon < 0.1, (Track isolation is defined as the sum of Pt of tracks within cone of |ΔR| < 0.3 around the muon direction i.e., ΣPt

trk/Ptµ in cone 0.3)

Two oppositely-charged muons are taken

Pseudorapidity of the muons |ηµ| < 2.4

The di-muon invariant mass between 85 and 97 GeV/c2 is considered

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Rejection of fake muon jets: |ΔRµ-jet| > 0.6 (To clean jets from isolated muons)

Transverse momentum > 9.0 GeV/c for all types of Jets(Calo, JPT and PF)

Pseudorapidity of the Calo, JPT and PF Jet with the highest transverse momentum :|ηJet| < 2.0

Jet Selection:

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Z plus one Jet selection: |ΔΦZ-Jet | > 2.7 rad. (Angular separation between Z boson

and the highest transverse momentum PF Jet) Used veto on the event such that: Pt(Z)>33 GeV/c and Pt(PFJet2)>0.3Pt(Z) reject events Pt(Z)< 33GeV/c and Pt(PFJet2)>10 GeV/c reject events |ΔR|(Between highest Pt PF Jet, Calo and JPT Jet) < 0.3 in

order to analyse the same Jet reconstructed with three types of algorithms

Transverse momentum(Pt> 20 GeV/c) distributions of 1st and 2nd muon candidates for reconstructing Z boson in the window 85 GeV/𝒄𝟐< Mµ+ µ- < 97 GeV/𝒄𝟐 and −2.4 < ηµ< 2. 4

Pseudo rapidity distribution of 1st and 2nd muon candidates for reconstructing Z Boson in the window 85 GeV/𝒄𝟐< Mµ+ µ- < 97 Gev/𝒄𝟐 and −2.4 < ηµ < 2. 4

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Dimuon Pt distribution reconstructed from muons in the window 85 GeV/𝒄𝟐< Mµ+ µ- < 97 GeV/𝒄𝟐 and −2.4 < η µ< 2. 4

Phi distribution of 1st and 2nd muon candidates for reconstructing Z Boson in the window 85 GeV/𝒄𝟐< Mµ+ µ- < 97 GeV/𝒄𝟐 and −2.4 < ηµ < 2. 4

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Mass of Z boson reconstructed from muons in the window 85 GeV/𝒄𝟐< Mµ+ µ- < 97 GeV/𝒄𝟐 and −2.4 < ηµ< 2. 4

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Transverse momentum of 1st energetic Calo, JPT and PF jet respectively. Here Pt ( Jet) > 9.0 GeV/c and |ΔΦZ-Jet|> 2.7 is applied for all three types of Jets

|ΔR| distribution between Leading PF Jet, Calo Jet and JPT Jet after 2nd Jet veto

|ΔR| distribution between Leading PF Jet , Calo Jet and JPT Jet after 2nd Jet veto. Here |ΔR| <0.3 is applied

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Distributions of Pt(Z)/Pt(JET) in all Pt(Z) range for CaloJet, JPT Jet and PF Jet.

Deltaphi distribution between highest Pt PF jet and Z boson

Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in all Pt(Z) range for CaloJet, JPT Jet and PF Jet.

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Calo 20-40 40-60 60-80 80-100 100-120

Mean 1.277±0.01504 1.199±0.00882 1.1410±0.006808 1.141±0.008169 1.117±0.008906

RMS 0.5242±0.01065 0.4595±0.00628 0.3782±0.004814 0.371±0.005777 0.3127±0.006296

RMS/Mean

0.41049±0.00963 0.3832±0.0059 0.3314±0.0046 0.3251±0.0055 0.2799±0.006

JPT

Mean 1.162±0.01065 1.172±0.007516 1.139±0.006297 1.14±0.007411 1.123±0.008463

RMS 0.3711±0.007529 0.3895±0.005315 0.3501±0.004452 0.3365±0.00524 0.2972±0.005984

RMS/Mean

0.3193±0.0071 0.3323±0.005 0.3073±0.0042 0.2951±0.0049 0.2646±0.00568

PF

Mean 1.128±0.007109 1.118±0.006629 1.083±0.005578 1.085±0.006233 1.084±0.007545

RMS 0.3504±0.007109 0.3436±0.004687 0.3104±0.003944 0.283±0.0044 0.2651±0.005335

RMS/Mean

0.3106±0.0068

0.3073±0.0045 0.2866±0.0039

0.2608±0.00432

0.2445±0.0052

Table for Mean, RMS and RMS/Mean of the ratio Pt(Z)/Pt(Jet)for Calo, Jpt and Pf jets for different Pt(Z) bins:

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Calo 20-40 40-60 60-80 80-100 100-120

µ

0.9101±0.0144 0.9407±0.0086 0.9533±0.0070 1.004±0.007 0.9938±0.0076

σ

0.1752±0.0086 0.1581±0.0048 0.1504±0.0042 0.1682±0.0042 0.1483±0.0053

σ/µ

0.1923±0.0099 0.1680±0.0053 0.1577±0.0045 0.1675±0.0043 0.1492±0.0054

JPT

µ

0.9711±0.0108 0.991±0.007 0.9723±0.0073 1.034±0.006 1.009±0.01

σ

0.1826±0.0071 0.1681±0.0042 0.1462±0.0048 0.1707±0.0042 0.1387±0.0058

σ/µ

0.188034±0.0076 0.1696±0.0044 0.1536±0.0050 0.1650±0.0041 0.1374±0.0059

PF

µ

0.9959±0.0126 0.9777±0.0052 0.9801±0.0046 1.001±0.005 1.012±0.006

σ 0.1896±0.0077 0.1564±0.0035 0.1472±0.0030 0.1564±0.0038 0.1494±0.0041

σ/µ

0.19038±0.0080

0.1599±0.0036 0.1501±0.0031

0.1562±0.0038

0.1476±0.0041

Table for Mean, Sigma and Sigma/Mean of the Ratio Pt(Z)/Pt(Jet)] for Calo, Jpt and Pf jets for different Pt(Z) bins:

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Calo 20-40 40-60 60-80 80-100 100-120

σEffe

0.4194±0 0.3103±0 0.2651±0 0.2457±0 0.2183±0

µ

0.9101±0.0144 0.9407±0.0086 0.9533±0.007 1.004±0.007 0.9938±0.0076

σEffe/µ

0.4608±0.0072 0.3298±0.0030 0.2781±0.0020 0.2447±0.0017 0.2197±0.0016

JPT

σEffe

0.3055±0 0.2722±0 0.2440±0 0.2276±0 0.2076±0

µ

0.97116±0.0108 0.991±0.007 0.9723±0.0073 1.034±0.006 1.009±0.010

σEffe/µ

0.3146±0.0034 0.2747±0.0019 0.2509±0.001 0.2201±0.0012 0.2057±0.002

PF

σEffe

0.2742±0. 0.240±0 0.2067±0 0.1988±0 0.1910±0

µ

0.9959±0.0126 0.9777±0.0052 0.9801±0.0046 1.001±0.005 1.012±0.006

σEffe/µ

0.2753±0.0034

0.2455±0.0013 0.2109±0.0009

0.1986±0.0009

0.1887±0.0011

Table for EffectiveSigma, Mean from Gaussian fit and EffectiveSigma/Mean Ratio of Pt(Z)/Pt(Jet)] for Calo, Jpt and Pf jets for different Pt(Z) bins:

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Jet Resolution Plots

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The PF Jet resolution is better than JPT and Calo Jet

Jet Reconstruction Efficiency= No. of Events in the leading Pt Jet satisfying |ΔΦZ-Jet1|> 2.7 in different Pt(Z) bins ------------------------------------------------------------------------------------------------------------ No. of events in Pt(Z) in different Pt(Z) bins

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Conclusions:

Here we discuss the energy resolution performance of the main three types of jets(Calo, JPT and PF) reconstructed at CMS

Analysis results of 1.97 fb-1 data of proton-proton LHC collisions at 7 TeV Center of mass energy collected data using 2011 run are presented

Jet reconstruction efficiency in bins of Pt(Z) for three types of Jet algorithm are shown.

Next to run over complete data of 2011 and the MC suggested by JA people and study for the forward Jet for the VBF process

Thank You!

Backup

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Definitions:

Jets: Jets are experimental signatures of quarks and gluons, which are produced in high energy processes such as the hard scattering of patrons in proton-proton collisions

Three main types of jets are reconstructed at CMS, which differently combine individual contributions from subdetectors to form the inputs to the jet clustering algorithm: Calorimeter jets, Jet Plus Track (JPT) jets and Particle Flow (PF) jets

Calo Jet: Calo Jet are reconstructed using energy deposits in the electromagnetic (ECAL) and Hadronic (HCAL) calorimeter cells, combined into calorimeter towers

Jet Plus Tracks(JPT) Jet : The JPT jet algorithm corrects the energy of a jet reconstructed from calorimetric energy deposition, using the momentum of charged particles measured in the tracker.

Particle Flow Jet: The particle flow jet algorithm combines the information from all CMS subdetectors to identify and reconstruct all the particles in the event, namely muons, electrons, photons, charged hadrons and neutral hadrons

In PF Jet , Charged hadrons, in particular are reconstructed from tracks in the central tracker. Photons and neutral hadrons are reconstructed from energy clusters in the electromagnetic and hadron calorimeters. Clusters separated from the extrapolated position of tracks in the calorimeters constitute a clear signature of these neutral particles. A neutral particle overlapping with charged particles in the calorimeters can be detected as a calorimeter energy excess with respect to the sum of the associated track momenta. PF jets are then reconstructed from the resulting list of particles

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Transverse momentum(Pt> 20 GeV/c) distribution of 1st and 2nd muon candidates for reconstructing Z Boson

Pseudo rapidity distribution of 1st and 2nd muon candidates for reconstructing Z Boson

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Phi distribution of 1st and 2nd muon candidates for reconstructing Z Boson

DiMuon Pt distribution reconstructed from muons without any cut

Mass of the Z boson reconstructed from muons without any cut.

Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in the Pt(Z) bin 20-40 GeV/c for Calo Jet, JPT Jet and PF Jet.

Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in the Pt(Z) bin 40-60 GeV/c for Calo Jet, JPT Jet and PF Jet.

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Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in the Pt(Z) bin 60-80 GeV/c for Calo Jet, JPT Jet and PF Jet.

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Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in the Pt(Z) bin 80-100 GeV/c for Calo Jet, JPT Jet and PF Jet.

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Gaussian fitted and superimpose distributions of Pt(Z)/Pt(JET) in the Pt(Z) bin 100-120 GeV/c for Calo Jet, JPT Jet and PF Jet.

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Used veto on the event such that if Cut( = 0.3 × Pt(Z) GeV) > 10 GeV and Pt(PFJet2)> Cut= 0.3 × Pt(Z) GeV , then reject the events and also if Cut < 10 GeV and Pt(PFJet2)> 10 GeV reject the events

Effective Sigma: It is the minimal width which contain 68% of events in the histogram and it is not necessary cantered on mean or median value. The resolution in % is then calculated as “SigmaEffective/median”

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