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Standard Model Results From CMS

Standard Model Results From CMS. Matt Herndon University of Wisconsin – Madison. Fermilab joint experimental theoretical seminar. Integrated Luminosity. M easurements are from 7 TeV and 8 TeV pp collisions I concentrate on newer measurements and some prospects

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Standard Model Results From CMS

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  1. Standard Model Results From CMS Matt Herndon University of Wisconsin – Madison Fermilabjoint experimental theoretical seminar

  2. Integrated Luminosity • Measurements are from 7 TeVand 8 TeVpp collisions • I concentrate on newer measurements and some prospects • All results shown can be found at: https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults Matthew Herndon, Wisconsin, FNAL 2013

  3. QCD Measurements • LHC/CMS Advantages • Multiple energies • Excellent detectors and techniques for object reconstruction. • CMS routinely uses particle flow • CMS starting to use Jet Substructure techniques • Large integrated luminosity and datasets • Control of Jet energy scale uncertainties in absolute and ratio measurements • Allows • Differential cross sections to high jet multiplicities • Multiple differential cross sections • Measuring the evolution of as • Constraint of PDFs • Probes in low cross section corners of the phase space. • Searches for new physics using dijets, multijet masses • Searches for new physics with boosted jets using jet substructure Matthew Herndon, Wisconsin, FNAL 2013

  4. Differential Jet Measurements • Jet cross sections • Global PDF sets show good agreement with the data • PDF sets not including high energy collider data have difficulty with high pt jet data • At 13-14 TeV these analyses will test our understanding of the data for early searches using jet data. CMS PAS SMP-12-012 Phys. Rev. D 87 (2013) 112002 Matthew Herndon, Wisconsin, FNAL 2013

  5. 3 Jet Mass, 2/3 Jet Ratio • 2-3 Jet ratios and 3 jet mass are used to extract as (also s(ttbar)) • Not competitive with world average as(mZ) • Complete NNLO calculation would improve extrapolation • Evolution of asto the highest region of Q • Non global PDFs continue to have trouble with high pT jet data CMS PAS SMP-12-027 CMS PAS TOP-12-022 CMS PAS QCD-11-003 Matthew Herndon, Wisconsin, FNAL 2013

  6. Jet Substructure • Jet Subtructure techniques • Identify massive objects decaying hadronically in boosted topologies. • W, Z top • Allows efficient detection of boosted W, Z, top • Grooming techniques improve data/simulation agreement • Also improves response vs. pile up • Essential in high mass resonance searches (already done at CMS) and in aTGC and aQGC searches where sensitivity is on the high pT tail of the vector boson pT distributions JHEP 05 (2013) 090 Matthew Herndon, Wisconsin, FNAL 2013

  7. W & Z Precision Measurements • Combination of several factors have made unprecedented precision measurements possible in a Hadron collider environment. • The capabilities and performance of the LHC experiments • The development sophisticated experimental techniques to treat collider data • The existence of inclusive and differential calculations of cross sections at NLO and now NNLO precision • The integration of matrix element MCs with parton shower generators in a consistent way at NLO (work to move to NNLO) • These factors allow an exciting program of measurements with sensitivity to essential issues. • pQCD tests at NLO and NNLO • Tests of matrix element + parton shower techniques to high jet multiplicity • PDF sensitivity • Test of Electroweak predictions for asymmetries and polarizations • Differential distributions for transverse momentum, rapidity, and jets • Associated production of vector boson and heavy flavor jets • Vector boson fusion and scattering Matthew Herndon, Wisconsin, FNAL 2013

  8. W & Z Cross Sections • Measurement of total W and Z cross sections. • pQCD test from ratio of 7 TeV to 8 TeV cross sections and W/Z, W+/W- • PDF sensitivity • Comparable experimental and theory uncertainty • 2-3% systematic and 5% luminosity uncertainty • Expect extrapolation to 13-14 TeV to be good CMS PAS SMP-12-011 JHEP 10 (2011) 132 Matthew Herndon, Wisconsin, FNAL 2013

  9. W and Z Cross Sections • Cancelation of systematic errors in ratio • both experimental and theoretical • Removes largest experimental uncertainty, luminosity • W/Z ratio at 8 TeV: ~1.5 sigma difference all PDF sets • 2% experimental systematic uncertainty. • Present at 7 TeV and in W+ and W- separately • With better precision discrepancies are found (look further for the source) CMS PAS SMP-12-011 JHEP 10 (2011) 132 Matthew Herndon, Wisconsin, FNAL 2013

  10. W+and W-Cross Sections • Cancelation of systematic errors in ratio • both experimental and theoretical • Removes largest experimental uncertainty, luminosity • Expect 2:1 ratio form valence quarks in valance-sea annihilation, diluted by sea-sea • Agrees with theory predictions • Tested at 2% level driven by experimental systematic uncertainty. CMS PAS SMP-12-011 Matthew Herndon, Wisconsin, FNAL 2013

  11. Z pT at 7 and 8 TeV Phys. Rev. D 85, 032002 (2012) CMS PAS SMP-12-025 • pT of Drell Yan (Z) production: • 60 < ml l< 120 GeV • Agreement with NNLO calculations • Matrix Element + PS generators • Madgraph slightly better at high qT – includes multiple hard emission • Resbos improves low qT region • V+jets important for VV scattering Matthew Herndon, Wisconsin, FNAL 2013

  12. Z Forward Backward Asymmetry • Z forward Backward asymmetry • Measured as a function of mass in four rapidity bins • Sensitivity to new physics such as new neutral vector bosons which would modify vector coupling of the leptons at high mass • Also measure the weak mixing angle. • Good agreement with theory: POWHEG+CT10 • Many sources of experimental uncertainty are statistics driven. Raw statistics and Tracker alignment. • Expected to be competitive with world average (with improved PDFs) Phys.Lett. B718 (2013) 752-772 Matthew Herndon, Wisconsin, FNAL 2013

  13. W Charge Asymmetry • Study of ratios of kinematic variables between W+ and W- production • Cancellation of systematic uncertainties in the ratio maximizing sensitivity to PDF • Valance-sea interaction and asymmetry increase at high y • Provides significant constraint on the global PDF fit CMS PAS SMP-12-021 Phys.Rev.Lett. 109 (2012) 111806 • Good agreement with several PDF sets (initially excluding MSTW in both electrons and muons) • MSTW fit now introduces new degrees of freedom for valance x distribution improving the agreement • Continue to improve PDFs in preparation for 13-14TEV Matthew Herndon, Wisconsin, FNAL 2013

  14. Z + jets • Z + 1jrapidity • Azimuthal correlations, Event shapes • Test of NLO theory and Matrix Element + parton shower MCs • Individual Z and jet rapidities look good • Combined distributions show deviations. • Combined rapidity, Event thrust • Test vs. newer theory tools • V(V)+jets important for VV scattering Phys. Lett. B722 (2013) 238 CMS PAS SMP-12-004 Matthew Herndon, Wisconsin, FNAL 2013

  15. VBF Z Production • EW VBF production of Z + jets • Dominant background from standard DY production • Uses multivariate (BDT) discriminant to extract signal • Includes a gluon vs. quark jet likelihood discriminant • Measures WWZ TGC CMS PAS FSQ-12-019 • σ(μμ+ee) = 154 ± 24 (stat.) ± 46 (syst.) ± 27 (th.) ± 3 (lum.)fb • VBFNLO 166 fb • Same topology as VBF Higgs and longitudinal vector boson scattering. Benchmark for EWSB studies Matthew Herndon, Wisconsin, FNAL 2013

  16. W + c-Jet • W+c‐jetproduction • Sensitive to strange PDF of the proton. • W charge the same as initial s quark • Strange anti-strange PDF should be ~symmetric • Analysis uses charm hadron reconstruction to identify charm jets. CMS PAS SMP-12-002 • Fair agreement with PDF fits • Competitive sensitivity to strange PDF compared to neutrino scattering experiments Matthew Herndon, Wisconsin, FNAL 2013

  17. Z + b-Jets • Production of Z + 1 or 2 b jets • Good agreement with predicted cross section across jet bins • Key distributions for ZH analysis look good CMS PAS SMP-13-004 Matthew Herndon, Wisconsin, FNAL 2013

  18. W + 2b-Jets • Production of W + 2 central b jets • History of disagreement in V+hf between theory and experimental data. Critical background for Higgs searches • Double tags events to remove W+c and constrain top contribution from high jet multiplicity region. • Good agreement with predicted cross section CMS PAS SMP-12-026 • Disagreement with V+b states localized to V+1b. Populated by merged low angle gluon splitting. Controlled in Higgs by data driven background estimates CMS PAS EWK-11-015 Matthew Herndon, Wisconsin, FNAL 2013

  19. Other V (+ jets) Results • Active program in V (+jets) (not shown here) • Photon + jets, Photon + Jets rapidities • W differential vs. n jet cross section • W polarization at large pT • DY cross section • Z differential vs. n jet cross section • Z  tautau Matthew Herndon, Wisconsin, FNAL 2013

  20. Multiboson Production • Fundamental test of Standard Model • Multiple vector boson interactions due to the gauge structure of the Standard Model • Test of QCD techniques in VV+jets • Probe for new physics • Indirect search for tree or loop effects of massive new particles in Anomalous Triple Gauge Couplings (TGC) and Quartic Gauge Couplings (QGC) • Quartic coupling especially sensitivity to EWSB including non SM contributions EWSB QGC TGC Matthew Herndon, Wisconsin, FNAL 2013

  21. γγProduction CMS PAS SMP-13-001 • Highest statistics diboson mode • Probes phase space regions where NNLO prediction is important • Differential NNLO prediction available • Best agreement with is with NNLO theory • Other predictions agree in phase spaces where they are expected to do well Matthew Herndon, Wisconsin, FNAL 2013

  22. Wγ, Zγ Production • Wγlνγ, Zγ llγννγ • Differential with γ in charged lepton modes • Minimum γET > 15 GeV • Also missing ET and γ with high ET in Zγννγ CMS PAS EWK-11-009 CMS PAS SMP-12-020 • Agreement with NLO theory (MCFM NLO, BAUR) • Don’t strongly confirm ATLAS excess • Need differential measurements including nJet and jet kinematics • Confirm our understanding of VV+jets for VV scattering or triple gauge boson production Matthew Herndon, Wisconsin, FNAL 2013

  23. Wγ, ZγaTGC • aTGC searches • Exploit expected high transverse momentum of vector boson if there is aTGC using γ Et distribution • Good sensitivity due to higher branching ratios in in Zγννγ • Zγννγ dominates sensitivity. • aTGC limits on ZZγ and Zγγ are worlds best • Limits on WWγ approaching LEP sensitivity • -0.38 < |Dkg| < 0.29 and -0.050 < |lg| < 0.037 CMS PAS EWK-11-009 CMS PAS SMP-12-020 Matthew Herndon, Wisconsin, FNAL 2013

  24. aTGC – interesting yet? • Are these aTGC limits interesting yet? • Useful to consider aTGC in effective field theory • Essentially the same as looking for weak force effect well below the mass scale of the W and Z • h ≈ cmV2/L2 • Natural assumption for coupling constant c: order 1 • Assumption new physics scale. 1 to 3 TeV • Therefore h3 = 1x10-4to 1x10-3 interesting • h4 described by higher dimension operator but limits 100x more stringent • At level of interesting sensitivity. Also higher order effects will become important Matthew Herndon, Wisconsin, FNAL 2013

  25. WW Production CMS PAS SMP-12-005 • Signal: dileptons (e and μ) and missing ET • Cross sections at 7 and 8 TeV • Apply jet veto to reduce top backgrounds Phys. Lett. B 721 (2013) 190 jet veto adds systematic uncertainty Removing 0 jet veto should be possible. Expand to 1 jet • Cross sections high at 1-1.5σ level compared to NLO • σ(WW7 TeV)= 52.4± 2.0(stat.) ± 4.5(sys.) ± 1.2(lum.) pb, MCFM: 47.0±2.0 pb • σ(WW8 TeV)= 69.9± 2.8(stat.) ± 5.6(sys.) ± 3.1(lum.) pb, MCFM: 57.3±2.0 pb • Expect contributions at 5% level from H  WW and other processes Matthew Herndon, Wisconsin, FNAL 2013

  26. WW aTGC • aTGCsearch • Exploit expected high transvers momentum of vector boson using leading lepton pT distribution • Limits Limits on WWγ and • WWZ approaching LEP sensitivity • -0.21 < |Dkg| < 0.22 • -0.048 < |lZ| < 0.048 • -0.095 < |gZ1| < 0.095 CMS PAS SMP-12-005 Matthew Herndon, Wisconsin, FNAL 2013

  27. WZ Production • Signal: trileptons (e and μ) and missing ET • Cross sections at 7 and 8 TeV • Sample pure enough to allow jet analysis CMS PAS SMP-12-006 • Highest cross section very low background VV mode • Interesting for testing theory predictions • Approximate NNLO available • Collinear radiation effects along a hard object can increase the hard cross section • Matrix element + PS at NLO available hep-ph/1209.4595 Matthew Herndon, Wisconsin, FNAL 2013

  28. WW+WZ Production • WW + WZ production in semileptonic decays • Signal: leptons (e and μ) and missing ET and two jets consistent with a W or Z • Cross sections at 7 • Apply jet veto to reduce top backgrounds Eur. Phys. J. C 73 (2013) 2283 Phys. Rev. Lett. 109 (2012) 251801 • Also used to search for higher mass resonance produced in associated with a W boson • No evidence of a resonance and limits placed on several models • First observation of WW+WZ: 2700 candidates • Cross section in agreement with theory • σ(WV 7 TeV)= 68.89 ± 8.71 (stat) ± 9.70 (syst) ± 1.52 (lumi) pb • MCFM NLO : 65.6 ± 2.2 pb Matthew Herndon, Wisconsin, FNAL 2013

  29. WW+WZ aTGC • aTGCsearch • Exploit expected high transverse momentum of vector boson using hadronically decaying vector boson pTdistribution • Weak sensitivity to gZ1. Set to SM value. Eur. Phys. J. C 73 (2013) 2283 • Limits Limits on WWγ and • WWZ • approaching LEP sensitivity • Continuing this analysis requires using jet substructure Probably not sensitive to NP yet. Will reach sensitivity with 13-14 TeV data or 8 TeV combination Matthew Herndon, Wisconsin, FNAL 2013

  30. ZZ Production • ZZ production in charged leptonic decays (e, μ and tau) • Cross sections at 7 and 8 TeV. Also Z  4l JHEP 12 (2012) 034 JHEP 01 (2013) 063 Phys. Lett. B 721 (2013) 190 CMS PAS SMP-13-005 • Cross sections in agreement with theory • σ( ZZ 7 TeV)= 6.2± 0.8(stat.) ± 0.4(sys.) ± 0.1(lum.) pb • MCFM NL) : 6.3 ± 0.4 pb • σ(ZZ 8 TeV)= 7.7± 0.5(stat.) ± 0.4(sys.) ± 0.3(lum.) pb • MCFM NLO : 7.7 ± 0.4pb Matthew Herndon, Wisconsin, FNAL 2013

  31. ZZ aTGC • aTGCsearch • Exploit expected high transvers momentum of vector bosons using the 4l mass. • World leading sensitivity to ZZγ and ZZZ CMS PAS SMP-13-005 • Very near interesting region for NP sensitivity Matthew Herndon, Wisconsin, FNAL 2013

  32. Summary of Cross Sections Matthew Herndon, Wisconsin, FNAL 2013

  33. Where to Next • Many places you might look for new physics • In the context of SM measurements? • Look for deviations in the EWSB sector • Compatibility with precision SM measurements with the observed Higgs boson • mt, mW • Longitudinal vector boson scattering Matthew Herndon, Wisconsin, FNAL 2013

  34. Top Mass • Has the LHC finally surpassed the Tevatron? • CMS: 0.56%(with 8 TeV), Best CMS measurement in 7 TeVl+jets • LHC: 0.54% • Tevatron: 0.50% (Tevatron result is still a moving target) CMS PAS TOP-13-003 CMS PAS TOP-13-005 JHEP 12 (2012) 105 Matthew Herndon, Wisconsin, FNAL 2013

  35. Top Mass Projections • Substantial improvement in top mass possible. • Good sensitivity from orthogonal methods with different limiting factors • 200 MeV sensitivity • Doesn’t address issue of defining the top pole mass • The W mass? • Not studied in detailed • Currently limited by PDF uncertainty at 10 MeV level. Data may allow improved PDFs JHEP 12 (2012) 105 CMS PAS FTR-13-017 Matthew Herndon, Wisconsin, FNAL 2013

  36. mTvsmW • LHC gets halfway to ILC type sensitivity. • Multiple orthogonal methods of top mass reconstruction may improve sensitivity in combination • Large datasets may improve PDF uncertainty in Wmass • Could be sensitivity to indicate non SM behavior Where to look next? Matthew Herndon, Wisconsin, FNAL 2013

  37. QGC and Vector Boson Scattering • Vector boson scattering interactions in the SM • Double triple gauge couplings, t and s channel • Quartic gauge coupling: WWγγ, WWZγ, WWWW, WWZZ • t channel scattering via a Higgs • Standard model expectation is precisely predicted given the Higgs mass • All scattering contributions individually rise quickly with CM energy and violate unitarity. • Unitarity conserved by interference effects. • New physics in scattering • Often described in generalized context of anomalous quartic gauge couplings (aQGCs) • Exchange of new heavy particlessuch as extra scalars (Higgs) is a direct window on non-SM electroweak symmetry breaking contributions. • NP would modify the interference and alter the differential cross section as a function of scattering CM energy. • Also triboson production Matthew Herndon, Wisconsin, FNAL 2013

  38. WWγ+WZγ (a)QGC • Signal: leptons (e and μ) and missing ET, dijet, photon • Search for SM WWγ+WZγProduction • aQGC Search for WWZγ, WWγγ, aQGC • Not sensitive to SM rate or likely aQGC CMS PAS SMP-13-009 Many studies of aQGC done. Now also some complete analysis! Expect that most scattering and 3V states accessible at 13-14TeV. SM or aQGC • σ(WVγ)<241 fb, 3.4x σSM Matthew Herndon, Wisconsin, FNAL 2013

  39. Search for gg WW and aQGC • gg WW in Central exclusive production • Signal: dileptons (eμ) and missing ET with central track veto • Use pTeμ to search for aQGC. CMS PAS FSQ-12-010 • Expect 2.2 ± 0.5 signal events, 0.84 ±0.13 background. Observe 2 • σ(ggWW) < 8.4 fb, SM: 3.8 ±0.9 LEP Near interesting region for SM and NP sensitivity Matthew Herndon, Wisconsin, FNAL 2013

  40. CMS PAS FTR-13-006 WZ Scattering and aQGC • Discovery potential for SM EWK WZ scattering and aQGC • WZ events in leptonic decays with forward scattering jets Matthew Herndon, Wisconsin, FNAL 2013

  41. Summary • Impressive number of SM results from the CMS • Precise tests of the Standard Model at TeVscale • Agreement with theory in most cases • Starting to set serious constraints on electroweak parameters and PDFs • Measurements are challenging NLO and NNLO predictions • Analysis approaching new physics sensitivity in the gauge sector • Still much of the LHC data at 8 TeV to be analyzed • More results with improved precision and new topics expected soon, stay tuned! • 13-14 TeV data will have strong sensitivity to new physics. • Though predicated on the excellence of theory predictions and experimental effort to validate them Matthew Herndon, Wisconsin, FNAL 2013

  42. Backup Matthew Herndon, Wisconsin, FNAL 2013

  43. W and Z Cross Sections • Cancelation of systematic errors in ratio • both experimental and theoretical • Removes largest experimental uncertainty, luminosity • W/Z ratio at 8 TeV: ~1.5 sigma difference all PDF sets • 2% experimental systematic uncertainty. • Present at 7TeV and in W+ and W- seperately also • With better precision discrepancies are found CMS PAS SMP-12-011 JHEP 10 (2011) 132 Matthew Herndon, Wisconsin, FNAL 2013

  44. Drell-Yan Cross Sections • Doubly differential in dσ/dMand rapidity in mass bins • dσ/dMfrom 15 to 1500 GeV • Rapidity from 0 to 2.4 in 6 mass bins • Comparisons with: • FEWZ + PDF sets • Agreement in dσ/dMand y. • Low mass sensitive to PDF and integration issues. • Understanding low mass dilepton pairs important for Higgs CMS PAS SMP-12-011 JHEP 10 (2011) 7 Matthew Herndon, Wisconsin, FNAL 2013

  45. W Charge Asymmetry • W charge asymmetry results both testing and then constraining PDFs • CMS and ATLAS results added in NNPDF2.2 reducing uncertainty. • Again improving PDFs in preparation for 13-14TEV Nucl.Phys. B855 (2012) 608-638 NNPDF Collaboration Matthew Herndon, Wisconsin, FNAL 2013

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