Quark Compositeness Study and Progress

Satyaki Bhattacharya, Sushil S. Chauhan, Brajesh C. Choudhary

& Debajyoti Choudhury

Department of Physics & Astrophysics

University of Delhi, India

India-CMS Meeting @ BARC

20-21 July 2007

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Outline

• Status of quark compositeness study.

• Work done at CERN.

• Some preliminary distributions of Gamma + Jet through q* exchange.

• Future Plans.

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Last India-CMS Meeting in April 2007

• qqbar Diphoton through q* exchange• We presented the final results

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arXive:0705.3472v1[hep-ph]

Also submitted to Phys. Rev. D

PUBLICATIONS

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CMS Internal NOTE

• BSM convenenor showed interest to make it as a CMS Internal Note.• The result was presented in the SUSY/BSM meeting at CERN on 8th Jun• Submitted as Internal Note. Waiting for response from referees

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Work done at CERN

• We have already started q* study with CMSSW.

• Currently using CMSSW_1_3_1

• Main focus is on isolation variable e.g, ECAL isolation, HCAL isolation, track isolation or some new variable e.g, Basic Clusters around photon.

∆ We have to provide the .cfg file for qq Diphoton through q*. (Interfacing it as an external process for better maintenance in future). Work is in progress..

∆ To prepare skim for 2 photon+ N Jet study. Work is in progress…..

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Preliminary Distribtutions

Background sample of Gamma + Jet ( 120GeV < Pt <170 GeV )

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Preliminary distributions cont…

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Preliminary distributions cont…

“ctfsTrackWithMaterial”

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q* study for Gamma +Jet final state

• In continuation of qq diphoton through q* exchange.• Feynman diagrams for the signal.

• Feynman diagrams for the backgrounds.

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Matrix Element for qg gamma+Jet via q*

For Standard Parametrization f1=f3=1, n1=n3=1. Is the compositeness scale and Mq* is the mass of q*

By: Prof. Debajyoti Choudhury

SM Piece

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Event Generation with PYTHIA

For generation of events the matrix element has been included in PYTHIA with showering and hadronization effects

Q2 = s-hat and CTEQ5L Cross-Section for q* Signal with PT (hat) > 190 GeV

=Mq* (TeV) ª ( pb )1. 0.5 75.87 2. 0.7 58.78

3. 1.0 47.96 4. 2.0 43.10 5. 3.0 42.59

6. 4.0 42.61

7. 5.0 42.55 x-section decreases with increasing Λ and approaches to SM

cross section. ª For standard parametrization

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Event generation with PYTHIA

Variation with respect to couplings

f1=f3 (pb)

1. 1.0 75.87

2. 0.5 51.64

3. 0.4 48.46

4. 0.3 45.89

5. 0.2 44.04

6. 0.1 42.94

7. 0.05 42.62

Λ=Mq*= 0.5 TeV, n1=n3=1

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Backgrounds

Pt –hat

50-100

GeV

100-200

GeV

200-400

GeV

400-600

GeV

600-1000

GeV

1000-1500

GeV

>1500

GeV

qg 4458 425.3 33.2 1.517 2.22 x 10-1 1.19 x 10 -2 7.6 x 10-4

qqbar 375.4 47.44 5.01 3.15 x 10-1 5.662 x 10-2 3.77 x 10 -3 2.77x 10 -4

gg 1.528 8.01x 10-2 3.08 x 10 -3 7.02 x 10-5 6.33 x 10-6 1.75 x 10 -6 5.81 x 10 -9

Cross Section (pb) for background in different Pt-hat bin

Pt –hat 50-100

GeV

100-200

GeV

200-400

GeV

400-600

GeV

600-1000

GeV

1000-1500

GeV

>1500

GeV

Z+Jet (Z jj)

2.80 6.18 x 10-1 8.61 x 10-2 6.18x 10-3 1.20 x10-3 8.47x 10-5 6.54 x10-6

W+Jet (W jj )

2.54 4.81x 10-1 6.06 x 10-2 4.09 x 10-3 7.39 x10-4 4.68 x10-5 2.99 x10-6

Type-2

Type-1

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Preliminary plots

The Iterative cone algorithm is used for Jet with jet cone size of RJet=0.6, Ptseed≥ 5 GeV.

~ 94% matching between Iterative Jet and Parton Jet (for eta difference < 0.2).

CMS reconstruction algorithm for photon.

Mq*= 0.5TeV

Log scale

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Preliminary plots

Λ=Mq*=1 TeV

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Preliminary plots

Λ= Mq*=1 TeV

For 1 pb-1 of Integrated Luminosity

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Future Plans

• Prepare “.cfg” files for the signal (qqbarγγ).• Prepare the “skim” files for 2 Photon +N Jet

and give them to production team as soon as possible.

• Complete the Gamma +Jet study at the Generator level, sent it for publication and release as a CMS document.

Thank you!

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Compositeness scale

Compositeness scale:• Λ >> sqrt (s-hat) : Contact interaction• Λ << sqrt (s-hat) : Excited state• Λ ~ sqrt (s-hat) : Model Dependent

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Efficiency after Pt and eta cuts

• Y+jet 1.43 % (1.5 x 10-2 %)

• Box 51.42 % ( 42.84 %)

• Born 62.42 % ( 53.54 %)

For Y+jet :

• Cos (theta) ~1.1 % (Pt and eta)

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Signal vs Background Distributions

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Generator Level Reconstruction Vs FAMOScont..

For Next-To-Leading Photon Candidate

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Those events where EGamma Super Clusters < Generated EGamma Super Clusters

Generator Level Reconstruction Vs FAMOScont..

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Present Limit on M*

– CDF: M* > 80 GeV (q*q )– CDF: M* > 150 GeV (q* q W )– CDF (All channels): M* >200 GeV – D0 : M*> 200 GeV

• Simulation study: Mass reach up to 0.94 TeV at Tevatron ( 2 TeV, 2 fb-1, q*q-qbar)

• ATLAS Study: upto 6.5 TeV at LHC ( f=fs=1, q*q )

Limits from Tevatron:

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Motivation

• Are quarks fundamental particles? OR Do they have sub-structure?

• Replication of three generation of quarks and leptons suggests the possibility that may have composite structures made up of more fundamental constituents

• Large Hadron Collider (LHC) will explore physics “Beyond the Standard Model” @ the TeV scale

• Excited quark state represents signal for substructure of quarks and physics beyond the SM

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Effects of Different Cuts

Events Type Cut A# events (efficiency)

Cut B# events (efficiency)

Cut C# events efficiency)

Cut A+Cut B+Cut C# events (efficiency)

Signal Events 52.13 ( 88.6 % ) 56.98( 96.87 % ) 56.09( 95.36 % ) 50.79 ( 86.35 % )

Total Background

43.91 ( 6.815 %) 55.32 ( 8.58 %) 63.62 ( 9.87 %)

42.66 ( 6.62 %)

S/B 1.18 1.03 0.88 1.19

+ Jet 6.63 ( 1.10 %) 14.51 ( 2.40 %) 23.49 ( 2.40 %) 6.35 ( 1.05 %)

gg 1.96 ( 85.73 %) 2.17 ( 94.94 %) 2.151 ( 93.96 %) 1.91 ( 83.41 %)

qqbar 35.324 ( 88.84 %)

38.63 ( 97.18 %) 37.98 ( 95.53 %) 34.39 ( 86.51 %)

So far best variables to discriminate the signal from background are,

Cut A: Riso< 0.35, ETsum< 5.0 GeVCut B: Riso< 0.35, Highest Tracks PT < 4.0 GeVCut C: Riso< 0.10, # of Tracks < 2

For L= 1 fb-1

Event Type without isolation cuts Total # of Events for L=1fb-1

Signal 58

Total Background+ Jet

q-qbargg

644

602

38

04

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Effects of Different Cuts …..

Events Type Cut A# events (efficiency)

Cut B# events (efficiency)

Cut C# events (efficiency)

Cut A +Cut B+ Cut C# events (efficiency)

Signal Events

52.13 (88.6% ) 51.11 ( 86.90 % ) 56.09 ( 95.36%) 48.17 ( 81.90 % )

Total Background

43.91 (6.815%) 44.24 ( 6.86 %) 63.62 ( 9.87 %) 40.09 ( 6.22 %)

S/B 1.18 1.15 0.88 1.20

+ Jet 6.63 ( 1.10%) 7.57 ( 1.25 %) 23.49 (2.409%) 5.64 ( 0.93%)

gg 1.96 ( 85.73%) 1.93 ( 84.34 %) 2.151 ( 93.96%) 1.80 ( 78.70 %)

qqbar 35.32 ( 88.84%) 34.74 ( 87.38%) 37.98 ( 95.53%) 32.65 ( 82.12 %)

Cut A: Riso< 0.35, ETsum< 5.0 GeVCut B: Riso< 0.35, Highest Tracks PT < 2.0 GeVCut C: Riso< 0.10, # of Tracks < 2

For L= 1 fb-1

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Nearest Track PT

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PT Sum of Tracks

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ET Sum

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# of Tracks

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Confidence Limits

• Earlier we were using LLR as the estimator for Confidence Limits (CL).

• But at 200 fb^-1 all the parameter space was getting excluded!! Did some checks e.g.:

As the mass bin are Gaussian distributed hence both should give same results Yet to understand the whole parameter space exclusion with LLR (May be we

would do it with full GEANT simulation).

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Generator Level Resonstruction Vs FAMOS

For leading Photon Candidates ( +Jet events)

For Next-To-Leading Photon Candidates of (+Jet sample)

φ ( radians)η