Search for Quark Substructure. Lee Pondrom & Yeongdae Shon. University of Wisconsin. For the CDF Collaboration

Transcription

1 Search for Quark Substructure Lee Pondrom & Yeongdae Shon University of Wisconsin For the CDF Collaboration

2 This study uses the event MC generator PYTHIA written by T. Sjostrand, Lund University and jet1 Et trigger data from CDFII 248/pb integrated luminosity at 1.96 TeV 2,5, events

3 CDF II Detector 1. Charged particle tracking 2. Hadron calorimetry 3. Muon detection

4 Electromagnetic and Hadronic Calorimeters Pb+scintillator and Fe + scintillator stacks Photomultiplier readout for each tower o Segmentation η=.1, φ=15 η=.5*log((1+cos(θ))/(1-cos(θ))) Appx 2towers total

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6 Calibration of the energy response test beam data, pions to 27 GeV Moveable radioactive sources laser flashers Charged particle tracking into towers Jet to parton calibration Jet recoil against single γ Jet recoil against Z ->ee/µµ Uniform detector response by Jet Et balance

7 Jet1 trigger Level 1 single tower Et>1 GeV Level2 cluster>9gev Level 3 Et>1GeV Offline cross section = 1 nanobarn 32 No prescale at luminosities <1 cm -2 sec -1

8 Event : Run : EventType : DATA Unpresc:,1,33,34,35,4,7,8,9,1,42,11,13,15,48,17,49,2,21,23,24,25,26,27,28 Presc:,33,3 Missing Et Et= 9.6 phi=2.6 List of Tracks Id pt phi eta Cdf Tracks: first To select track type SelectCdfTrack(Id) Svt Tracks: first e e Particles: first 5 pdg pt phi eta To list all particles ListCdfParticles() Jets(R =.7): first 5 Em/Tot et phi eta To list all jets ListCdfJets() Et = GeV To select track type SelectSvtTrack(Id)

9 Event : Run : EventType : DATA Unpresc:,1,33,34,35,4,7,8,9,1,42,11,13,15,48,17,49,2,21,23,24,25,26,27,28 Presc:,33,34,4, E T Missing Et Et= 9.6 phi=2.6 Jet Collection: JetCluModule 2 1 η Particles: first 5 pdg pt phi eta φ 1 Jets(R =.7): first 5 Em/Tot et phi eta

10 JetAna: jet1 Et7 CDF Preliminary JetAna_et_jet17 Entries JetAna: Mass for jets cone 7 JetAna_jet_jet_mass7 Entries jet1 data Mean 153 RMS Underflow Mean RMS Underflow 1 4 Overflow 44 Integral 2.19e Overflow 14 Integral 2.21e Et GeV mass GeV JetAna: Et diff for jets cone.7 24 x (Et1-Et2)/sum JetAna_Et_diff7 Entries Mean.1246 RMS.124 Underflow Overflow Integral 2.21e JetAna: dijet Phi diff7 2 x JetAna_phi_diff7 Entries Mean RMS.246 Underflow 849 Overflow 26 Integral 2.2e redians

11 JetAna: jet1 eta jet1 data CDF Preliminary JetAna_eta_jet17 Entries Mean RMS.9844 Underflow Overflow Integral 2.21e+6 JetAna: Jet eta for 7 GeV jets JetAna_jet_eta_highm4 Entries Mean RMS 1.52 Underflow Overflow Integral 2.697e JetAna: Jet Et for 7 GeV jets JetAna_jet_et_highm4 JetAna: Chi for jets 7GeV JetAna_jet_chi7 Entries Mean Entries 2948 Mean RMS Underflow 4 RMS 8.51 Underflow 1 2 Overflow 1 Integral 2.697e Overflow 256 Integral 1.844e χ=cot (θ*/2) 1 5 χ

12 PYTHIA 2->2 QCD Processes q i q i q i +q ->q i +q i,j same/diff flavor j j + q i -> q k + q k i,k same/diff +q i -> g + g q i +q j -> q i +q j g + g-> g + g g + g->q i +q i g + q i ->g+ q i or q i

13 PYTHIA does initial and final state radiation Pythia also does parton fragmentation->particles Then the CDF Simulation takes over Detector geometry Energy response of calorimeters Trigger simulation

14 PYTHIA can model new physics in 2->2 processes for quark substructure PYTHIA follows Eichten, Lane, and Peskin, PRL 5, 811(1983)> color singlet left handed Lagrangian term 2 2 µ L=±(g /2Λ )(q L γ µ q L )(q L γ q L ) Affects q+q and q+q channels * o Increases the cross section near θ =9

15 Quarksub Lagrangian looks like muon decay. Eichten et al say "strong forces binding quark constituents induce flavor diagonal contact interactions." Mass scale Λ characterizes the size of the quarks Two of the q+q->q+q sub processes have interference terms 2 ±(s/λ ) The remainder have only the term proportional to 2 2 (s/λ )

16 To Understand what PYTHIA does: 1.) Write a little program for 2->2 scattering using QCD formulas of Combridge, PL7B,234(1977). 2.) Download standalone PYTHIA from LUND it compiled and ran! 3.) Switch off initial and final state radiation 4.) Compare PYTHIA 2->2 with (1) above

17 Angular Distribution in the jet jet c of m dn/dχ where χ=exp η1-η2 2 or χ=cot (θ*/2) 4 if dσ/dω = 1/sin (θ*/2) then dn/dχ = flat

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20 As a first look, Compare jet1 data to 2->2 parton level χ distributions Four jet-jet mass bins: 4, 5, 6, and 7 GeV nominal Agreement with lowest order QCD not so bad More work needed to set limits on Λ

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22 JetP: Chi for jets 6GeV CDF Preliminary Pythia MC JetP_jet_chi6 Entries Mean RMS Underflow Overflow Integral 6.451e e+4 JetP: Chi for jets 7GeV blue Λ=-1TeV black Λ=-1.4TeV red=noqsub JetP_jet_chi7 Entries 3312 Mean RMS 8.47 Underflow Overflow 441 Integral 2.861e χ 2 χ JetP: Chi for jets 8GeV 5 4 JetP_jet_chi8 Entries 178 Mean RMS Underflow Overflow 1648 Integral 843 JetP: Chi for jets 9GeV 25 2 JetP_jet_chi9 Entries 3668 Mean RMS Underflow Overflow 548 Integral χ χ

23 JetP: Chi for jets 6GeV JetAna_jet_chi6 JetP_jet_chi6 JetP: Chi for jets 7GeV JetAna_jet_chi7 JetP_jet_chi7 Entries Entries CDF Preliminary jet1 data black Mean RMS Underflow Overflow Integral 6.451e e e Λ=-1TeV blue noqsub=red Mean RMS Underflow Overflow Integral 2.861e e e JetP: Chi for jets 8GeV JetAna_jet_chi8 JetP_jet_chi8 Entries Mean JetP: Chi for jets 9GeV 25 JetAna_jet_chi9 JetP_jet_chi9 Entries Mean RMS Underflow Overflow RMS Underflow Overflow Integral Integral

24 sum the χ bins 1<χ<1 calculate the ratio (sum mc Λ)/(sum mc noqsub) 4 plot vs (mass) for various Λ obtain slopes for each Λ, plot slopes vs 1/Λ 4 compare to the slope from χ sum ratio data/(mc noqsub)

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26 JetAna: jet1 Et CDF Preliminary jet1 data black MC noqsub red Λ=-1TeV blue JetP_et_jet17 JetAna_et_jet17 Entries Mean RMS Underflow 156 Overflow Integral 5.693e e e Et1 GeV

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28 Conclusions conservative limit Λ>2.1 TeV 9% conf D limit PRD62,3111R(2). Λ>2.TeV 95% conf Data and MC have comparable statistical errors Systematics need to be studied

29 Conclusions cont d 6 CDF now has 5x1 jet1 events analyzed This will double the data sample Which will require more MC Expect no dramatic change in the limit This study is PYTHIA based