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First Results of ATLAS at the LHC -- The rediscovery of the Standard Model--

First Results of ATLAS at the LHC -- The rediscovery of the Standard Model--. Contents: Intro: The Standard Model Elementairy particles. Status LHC and ATLAS Physics results 2010. The Standard Model. Higgs mechanisme to generate mass! Higgs boson mass > 114 GeV.

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First Results of ATLAS at the LHC -- The rediscovery of the Standard Model--

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  1. First Results of ATLAS at the LHC--The rediscovery of the Standard Model-- Contents: Intro: The Standard Model Elementairy particles. Status LHC and ATLAS Physics results 2010 Marcel Vreeswijk (Nikhef/UvA-IoP)

  2. The Standard Model Higgs mechanisme to generate mass! Higgs boson mass > 114 GeV So, what have we been doing in 2010? Measuring ‘backgrounds’! Ultimate goal: detect the Higgs particle (not yet;need more data!)

  3. Large Hadron Collider (LHC) CERN site The LUMINOSITY represents the delivered number of proton collisions atlas In addition: Pb+Pb collisions (not in this talk) LHC P+P at 7TeV 27km 60 ton He at 2K 4 big experiments this talk: ATLAS First year of running. (7TeV) high quality data 2010: ~35pb-1 In 2011: run at 7TeV or higher? >>10-fold luminosity? Marcel Vreeswijk (Nikhef/UvA-IoP)

  4. LHC physics reach # events in 2010 Proton-Proton N = L . s N = # collisions L = Luminosity s = cross-section 5 T • Production Cross-section of top quarks and W, Z bosons are measurable with 2010 data! • Top, W,Z signals are important: • Standard candles for calibration • Background to new physics & Higgs searches In reach in 2010 1 M W,Z bosons 1000 Top quarks 1 Higgs W, Z Higgs W, Z Promising final states: H  W+W-  2 leptons + EtMiss H  ZZ  4 leptons AlsoH  2 photons 7TeV in 2010 Marcel Vreeswijk (Nikhef/UvA-IoP) jargon: lepton=electron or muon

  5. Inner detector (charged particle tracks) Calorimeter (energy all particles, but muons) Muon ‘Chambers’ ATLAS p Data rec. 93.5% #working channels >99% Marcel Vreeswijk (Nikhef/UvA-IoP)

  6. Inner Tracker p+ Ks Kaon discovery: 1947 p- Performance Inner Tracker Pixel detector (80M channels) Silicon strips (6M channels) TRT (350k channels) Operational for 97.5% Momentum measurement in magnetic field of 2T Resolution σ(pT)/pT = 0.05%pT ⊕ 1% 1 m Marcel Vreeswijk (Nikhef/UvA-IoP)

  7. Rediscovery of the p0 g since1950 p0 g Performance Calorimeter electromagnetic: Liquid Argon sampling calorimeter. Resolution ~10%/sqrt(E) Granularity: eta x phi=0.025 x 0.025 8m Marcel Vreeswijk (Nikhef/UvA-IoP)

  8. Di-jet physics Marcel Vreeswijk (Nikhef/UvA-IoP)

  9. jet p p jet Di-jet invariant mass • New energy domain. • Highest Pt jet: 1.12 TeV • Highest mass: 3.7 TeV • Searches for new physics ongoing ATLAS published 3 papers on jet measurements Marcel Vreeswijk (Nikhef/UvA-IoP)

  10. Performance Muons • Muon system: • Muon chamber • 350k drift tubes • (air core toroidal field 0.5T) • Designed for TeV muons (not yet) Physics signals show up! Z boson ‘rediscovered’ Originally:1983 at CERN Mass: 91.19 GeV Marcel Vreeswijk (Nikhef/UvA-IoP)

  11. m+ ? mass m- Muon resonancesATLAS 2010 Published 2010 1963 1960 1974 1977 1983 Z cross-section in new energy domain=7TeV Marcel Vreeswijk (Nikhef/UvA-IoP)

  12. m n Missing Transverse energy W boson ‘rediscovered’ Originally:1983 at CERN Mass: 80.4 GeV Marcel Vreeswijk (Nikhef/UvA-IoP)

  13. m q W n g q’ W boson production Transverse W mass: W decays to muon + (unseen) neutrino. • Missing transverse energy. Marcel Vreeswijk (Nikhef/UvA-IoP)

  14. t p p t Top pair (ttbar) production • complicated events: • Many jets with 2 b-jets (can be ‘tagged’) • Electron or Muon • EtMiss • Standard candle • New physics may show up ttbar single-lepton Datum Basic prper. Europ. Topds! Last heaviest known particle Last before new • ttbar has two measurable decays modes: • single-lepton • di-lepton (mode is set by W decay) Marcel Vreeswijk (Nikhef/UvA-IoP)

  15. di-leptonic ttbar 2 b-tagged jets Marcel Vreeswijk (Nikhef/UvA-IoP)

  16. ttbar More info on poster by Ido & Hegoi N. from Nikhef Van Tera naar 100evts selectie Speld hooi Marcel Vreeswijk (Nikhef/UvA-IoP)

  17. ttbar: theory & experiment Marcel Vreeswijk (Nikhef/UvA-IoP)

  18. The LHC and the ATLAS detector have demonstrated to be ready for the Standard Model Higgs or new physics See next talk by Paul de Jong! Higgs in 2011 ? Conclusion We have measured the ‘backgrounds’, now we are ready for the signal ! Marcel Vreeswijk (Nikhef/UvA-IoP)

  19. Limits on mh from theoryLimits on mh from exper. “We know everything about the Higgs boson except its mass” Higgs mass (GeV) Triviality Vacuum stability Λ (GeV) BACKUP Marcel Vreeswijk (Nikhef/UvA-IoP)

  20. W boson cross section Marcel Vreeswijk (Nikhef/UvA-IoP)

  21. Photon production (QCD compton) • photons of hundreds of GeVs ! • (Xray 0.0001 GeV) Marcel Vreeswijk (Nikhef/UvA-IoP)

  22. Marcel Vreeswijk (Nikhef/UvA-IoP)

  23. Marcel Vreeswijk (Nikhef/UvA-IoP)

  24. The Standard Model + Higgs boson to generate mass! Promising decay modes H  2 photons H  W+W-  2 leptons + EtMiss H  ZZ  4 leptons and much more…. Ultimate goal: detect the Higgs particle (not yet…need more data!) So, what have we been doing in 2010? Measuring ‘backgrounds’! Marcel Vreeswijk (Nikhef/UvA-IoP)

  25. The Standard Model # events in 2010 Proton-Proton Note: a proton=many quarks+gluons 5 T • Production Cross-section of top quarks and W, Z bosons are measurable with 2010 data! • Top, W,Z signals are important: • Standard candles for calibration • Background to new physics & Higgs searches In reach in 2010 1 M W,Z bosons 1000 Top quarks Higgs 1 W, Z Higgs W, Z Promising final states: H  W+W-  2 leptons + EtMiss H  ZZ  4 leptons AlsoH  2 photons 7TeV in 2010 Marcel Vreeswijk (Nikhef/UvA-IoP) jargon: lepton=electron or muon

  26. CERN site The LUMINOSITY represents the delivered number of proton collisions 3.2T botsingen 655k hi Pb=Pb LHC P+P at 7TeV 27km 60 ton He at 2K 4 big experiments this talk: ATLAS First year of running. (7TeV) high quality data 2010: ~35pb-1 This year (2011): run at 7TeV or higher? >>10-fold luminosity? Marcel Vreeswijk (Nikhef/UvA-IoP)

  27. Z boson production Datum Z massa 2Gev wordt 90GeV • Do we understand Z production and its backgrounds? • First measurement ever at 7 TeV. Ook in e+e- Diagrammen Lin schaal? Marcel Vreeswijk (Nikhef/UvA-IoP)

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