Mock Data Challenge PbPb collisions - July 2010

Prashant ShuklaNuclear Physics DivisionBARC, Mumbai India

1India CMS, 29-30 July 2010, BARC, Mumbai

PbPb Run Status

1. Heavy Ion PbPb collisions: November – December 2010

5.5 TeV ---> 4 TeV --> 2.76 TeV

2. Integrated Luminosity

Rough estimates 10 to 50 µb-1.

Mock Data Challenge in July 2nd week.

Hydjet Events, Signals (Z0, photons, jets) embedded.

Aims:

Test the preparedness of the analysis flow/framework.

Stress test for all tools; condor, crab jobs.

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Heavy Ion Physics Analysis Groups

1. Charged Particle Spectra (Edward Wengar)

a) Pseudorapidity distribution of charged hadrons.

b) Charged hadron transverse momentum spectra

c) Transverse momentum spectra of identified hadrons

2. High PT Group (Marguerite B. Tonjes)

a) π0 RAA (C. Maguire)

b) Direct photons RAA ( '' )

c) Jet: Transverse energy

3. Correlation/Flow ( Julia Velkovska)

a) Dihadron correlation -->

Correlation between identified CalJets (10-15 GeV) and associated

tracket track (2-4 GeV).

b) Eleptic flow v2 = < cos 2 (atan(py/px)) > Pressure tarnsfer from y to x

4. Dileptons (Catherine Silvestre)

Z0->mumu,

Quarkonia ( J/psi, B2Jpsi, Upsilon) 3

Dilepton Group : aim

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Aim is to produce following spectrum for PbPb --> Z0, J/psi, B->J/psi , Y

BPH‐10‐002 & 003:

1. 2000 J/ψ with 18 nb –1

σ = 221 ± 46 ± 70 nb

2. 211 Y with 80 nb –1

σ = 9.7 ± 0.9 ± 1.1 nb

Extrapolation from pp

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X- section at 2.76 TeV = 11065.4 pb

Ratio (2.76/7.0) = 0.422897

77 Z0->mumu in pp for 198 nb-1

70 Z0->mumu in PbPb for 10 nb-1

July Exercise by Heavy Ion Dilepton Group

Start with Z0 embedded Hydjet Data

• Skimming (Hyunchul)• Checking (di)muon plots (Mihee)• Signal extraction (Vineet, Prashant, Cath)• Acceptance and efficiency corrections (DongHo)• Alternate method (Jorge, Camelia)• Rcp (Camelia)

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The Framwork: (Vineet) Skim0 -> Heavy Ion specific Skim1 -> Dilepton Specific Histograms Filling Fits

Z0 signals with July

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400 Signals were embedded in Hydjet

Reconstructed signalwith two global muon tracks.

More details by Vineet

Spectra Group

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Pseudo Rapidity distribution of charged tracks

0-10 % Central Corrected by Hydjet

Consistency is 3 % level.

Photon Analysis

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Reconstruction of Pi0 ---> 2 photons

1. To show if ECAL calibrations work for HI events

--> Direct photon spectrum for ET = 20 GeV to 100 GeV

2. RAA of pi0 over large pT and centarlity coverage.

Aims of July exercise:

Show that the pi0 mass peak can be reconstructed over a wide pT and centrality.

Workflow:

Reco -> 3X3 Cluster Finder -> Ntuple -> combine clusters to make pi0

cluster pT > 0.75 GeV, pair pT > 2 GeV

Adopted from pp

Pi0 -> 2 photons

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30000 events for 50 -100 % centrality

pT = 2-8 GeV/c

Jets and Dijets reconstruction

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Event Selection

Top 20 % Centrality

Dijet selection

Jet Eta < 2.0

Dijet dPhi > 2.5

100 GeV < Leading Jet Et < 170 GeV, 50 GeV < Away Jet Et

Dijet Statistics

220 Dijets

Track Selection

hiSelectedTracks, pt > 1.2 GeV

Jets reconstruction

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Jets reconstruction Jets reconstruction

Event Characterization

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1. Vertexing

2. Centrality

3. Trigger Efficiency

4. Event Plane

Event Characterization techniques for

Summary and Outlook

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1. Most of the analysis framework is ready: First spectra will be quick: In 2 weeks after reconstruction

2. Many analysis in PbPb benefit by pp exeprience

3. The statistics of signals will similar to pp.

4. BARC participation in dileptons is significant.