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 BARC July 2007

2 Outline Status of quark compositeness study. Work done at CERN. Some preliminary distributions of Gamma + Jet through q* exchange. Future Plans.

3 Last India-CMS Meeting in April 2007 qqbar  Diphoton through q* exchange We presented the final results

4 arXive: v1[hep-ph] Also submitted to Phys. Rev. D PUBLICATIONS

5 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 8 th Jun Submitted as Internal Note. Waiting for response from referees

6 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…..

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

8 Preliminary distributions cont…

9 “ctfsTrackWithMaterial”

10 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.

11 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

12 Event Generation with PYTHIA  For generation of events the matrix element has been included in PYTHIA with showering and hadronization effects  Q 2 = s-hat and CTEQ5L  Cross-Section for q* Signal with P T (hat) > 190 GeV  =Mq* (TeV)  ª ( pb ) x-section decreases with increasing Λ and approaches to SM cross section. ª For standard parametrization

13 Event generation with PYTHIA  Variation with respect to couplings f1=f3  (pb) Λ=Mq*= 0.5 TeV, n1=n3=1

14 Backgrounds Pt – hat GeV GeV GeV GeV GeV GeV >1500 GeV qg x x x qqbar x x x x gg x x x x x x Cross Section (pb) for background in different Pt-hat bin Pt –hat GeV GeV GeV GeV GeV GeV >1500 GeV Z+Jet (Z  jj) x x x x x x10 -6 W+Jet (W  jj ) x x x x x x10 -6 Type-2 Type-1

15 Preliminary plots The Iterative cone algorithm is used for Jet with jet cone size of R Jet =0.6, Pt seed ≥ 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

16 Preliminary plots Λ=Mq*=1 TeV

17 Preliminary plots Λ= Mq*=1 TeV For 1 pb -1 of Integrated Luminosity

18 Future Plans Prepare “.cfg” files for the signal (qqbar  γγ ). 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!

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

21 Efficiency after Pt and eta cuts Y+jet  1.43 % (1.5 x %) Box  % ( %) Born  % ( %) For Y+jet : Cos (theta) ~1.1 % (Pt and eta)

22 Signal vs Background Distributions

23 Generator Level Reconstruction Vs FAMOS cont.. For Next-To-Leading Photon Candidate

24  Those events where EGamma Super Clusters < Generated EGamma Super Clusters Generator Level Reconstruction Vs FAMOS cont..

25 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=f s =1, q*  q  ) Limits from Tevatron:

26 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 the TeV scale Excited quark state represents signal for substructure of quarks and physics beyond the SM

27 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 ( 88.6 % )56.98( % )56.09( % )50.79 ( % ) Total Background ( %)55.32 ( 8.58 %)63.62 ( 9.87 %)42.66 ( 6.62 %) S/B  + Jet 6.63 ( 1.10 %)14.51 ( 2.40 %)23.49 ( 2.40 %)6.35 ( 1.05 %) gg   1.96 ( %)2.17 ( %)2.151 ( %)1.91 ( %) qqbar   ( %)38.63 ( %)37.98 ( %)34.39 ( %) So far best variables to discriminate the signal from background are, Cut A: R iso < 0.35, E Tsum < 5.0 GeV Cut B: R iso < 0.35, Highest Tracks P T < 4.0 GeV Cut C: R iso < 0.10, # of Tracks < 2 For L= 1 fb -1 Event Type without isolation cutsTotal # of Events for L=1fb -1 Signal58 Total Background  + Jet q-qbar   gg  

28 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 (88.6% ) ( % ) ( 95.36%)48.17 ( % ) Total Background (6.815%) ( 6.86 %)63.62 ( 9.87 %) ( 6.22 %) S/B  + Jet 6.63 ( 1.10%)7.57 ( 1.25 %)23.49 (2.409%)5.64 ( 0.93%) gg   1.96 ( 85.73%)1.93 ( %)2.151 ( 93.96%)1.80 ( %) qqbar   ( 88.84%)34.74 ( 87.38%)37.98 ( 95.53%)32.65 ( %) Cut A: R iso < 0.35, E Tsum < 5.0 GeV Cut B: R iso < 0.35, Highest Tracks P T < 2.0 GeV Cut C: R iso < 0.10, # of Tracks < 2 For L= 1 fb -1

29 Nearest Track P T

30 P T Sum of Tracks

31 E T Sum

32 # of Tracks

33 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).

34 Generator Level Resonstruction Vs FAMOS For leading Photon Candidates (  +Jet events ) For Next-To-Leading Photon Candidates of (  +Jet sample) φ ( radians) η