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ATLAS : highlights from the first run and prospects for 2011

ATLAS : highlights from the first run and prospects for 2011. PbPb. pp. Recorded Delivered. Recorded Delivered. ~ 93.6%. ~ 94.6%. Fraction of good quality data (heavy-ion run). Fraction of good quality data (full pp run).  U sed for analysis: 80-85% of delivered luminosity

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ATLAS : highlights from the first run and prospects for 2011

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  1. ATLAS: highlights from the first run and prospects for 2011

  2. PbPb pp Recorded Delivered Recorded Delivered ~ 93.6% ~ 94.6% Fraction of good quality data (heavy-ion run) Fraction of good quality data (full pp run) •  Used for analysis: 80-85% of delivered luminosity • with first-pass processing • hope to improve to > 85% after data reprocessing • Cfr: Tevatron experiments: ~ 80% •  Used for analysis: 80-85% of delivered luminosity • with first-pass processing • hope to improve to > 85% after data reprocessing • Cfr: Tevatron experiments: ~ 80%

  3. November: jet “quenching” in HI August: more searches beyond Tevatron October: highest mass di-jet event (3.7 TeV) September: updated Higgs projections for 2011 July: first searches beyond Tevatron June: first top candidates April:1st W May: 1st Z

  4. First W  lν and Z  ll measurements Z  μμ MC In the full data sample recorded this year, ATLAS has: ~ 250k W μν, eν events ~ 23k Z  μμ, ee events  50 times less than CDF or D0 • Excellent agreement with Standard Model • Error dominated by 11% luminosity uncertainty

  5. Top-quark: the heaviest (and most intriguing …) elementary particle observed so far Di-lepton channel tt  bW bW  blν blν The most spectacular ATLAS candidate e,μ ν pT(μ)= 51 GeVpT(e)=66 GeVpT (b-tagged jets) =174,45 GeV ETmiss= 113 GeV, Secondary vertices: distance from primary vertex: 4mm,3.9mm vertex mass : ~2 GeV,~ 4GeV

  6. First top measurements at √s = 7 TeV (mtop= 172 GeV) In the full data sample recorded this year, ATLAS has ~ 700 top-antitop events  only ~ 8 times less than CDF or D0

  7. First limits beyond the Tevatron reach : from dijet final states Highest mass dijet in our data: Mjj =3.7 TeV ET jet1 ~ 670 GeV ET jet2 ~ 610 GeV

  8. Look for di-jet resonances in the measured M(jj) distribution Look for deviations from QCD in the measured di-jet angular distributions • Standard Model: χ distribution ~ flat • Quark sub-structures: excess at low χ Exploration of the TeV scale started in earnest q*  qg ~ 0.5 TeV beyond the Tevatron limits ATLAS: M (q*) > 1.5 TeV ATLAS: Λ > 3.4 TeV

  9. First direct observation of “jet quenching” in heavy-ion collisions One of main goals of high-energy HI collisions: recreate “plasma of free quarks and gluons” “quark-gluon plasma” that (we think) permeated the Universe ~ 10 μs after Big Bang Jets produced in HI collisions would be “quenched” by interacting with the (dense) plasma  expect asymmetric dijets final states • First asymmetric • dijet events • observed by ATLAS • on 8 November • (first day of Pb-Pb • stable beam collisions) • paper submitted • for publication in • Physical Review Letters • on 25 November

  10. An asymmetric dijet event with a “quenched jet”

  11. Where are we today ? Next to come … ? Candidate ZZ  event Jets ✔ W ✔ Z ✔ top ✔ Known SM processes Single-top WW, ZZ, WZ Higgs, mH~120 GeV DISCOVERIES ! By increasing difficulty: Z’, W’, SUSY, Higgs W’ m= 1.5 TeV Z’ m= 1.5 TeV

  12. W’  lν, Z’  ll • Would indicate existence of new (small scale) forces (in addition to the known four) • Present Tevatron limits: ~ 1 TeV 45 pb-1 1 fb-1 5 fb-1 W’ 1.2 TeV 2 TeV 2.4TeV Z’ -- 1.5 TeV 2 TeV ATLAS discovery reach at 7 TeV (very preliminary  more in Chamonix) • Our present best candidate for Universe's dark matter (SUSY’s neutralino) would be • produced in the cascade decays of squarks and gluinos. • Tevatron (exclusion) reach: ~ 450 GeV 1 fb-1 2 fb-1 5 fb-1 √s=7 TeV 0.7 TeV 0.8 TeV 1 TeV √s=8 TeV 0.8 TeV 0.9 TeV 1.1 TeV ATLAS discovery reach (very preliminary  more in Chamonix)

  13. 2011 (2012): the year(s) of the Higgs ? … and of the “race” with Tevatron … Higgs in ATLAS

  14. What do we know today ? • Theory: mH < 1 TeV • Present experimental exclusion: mH > 114.4 GeV (LEP), 158 < mH < 175 GeV (Tevatron) • Favoured region (electroweak data  consistency of Standard Model): mH < 158 GeV •  114.4-158 GeV is the “hottest” region (although higher masses cannot be excluded) • Tevatron luminosity projections: • “Analyzable” by CDF, D0 (i.e. good data quality): ~ 80% of delivered • Today: ~ 9 fb-1 delivered  up to ~ 7 fb-1 analyzed by CDF, D0 • Delivered per year: ~ 2.5 fb-1 ~ 2 fb-1analyzable • 2011: ~ 12 fb-1 delivered  10 fb-1 analyzable • 2014 (if run extended by 3 more years): ~ 20 fb-1 delivered  ~ 16 fb-1 analyzable The Tevatron-LHC complementarity Most difficult region at LHC: mH ~ 114-115 GeV Most difficult region at the Tevatron: mH ~ 135 GeV For mH ~ 115 GeV: best channel at LHC: H  γγ best channel at the Tevatron: WH, ZH with H  bb • Note: • Tevatron analyses very sophisticated (combinations of many decay modes, neural • networks with huge number of input variables, etc.) • LHC projections: very conservative  ATLAS and CMS can do better than shown here • Tevatron: no discovery (5σ) reach (not even if extended by 3 years); max 3σ evidence

  15. Tevatron excluded LEP excluded 2014 Tevatron 2011

  16. Here LHC means ATLAS and CMS combined (very preliminary) Expected Higgs mass coverage (GeV) • Tevatron LHC LHC LHC LHC • 10 fb-1(end 2011) 1 fb-1 7 TeV 1 fb-1 8 TeV 2.5 fb-1 8 TeV 5 fb-1 8 TeV • 95% CL exclusion 114-185 123-550 120-570 114-600 ≥ 114 • 3 σ evidence ~115, 150-180 130-450 127-500 123-530 ≥ 114 • 5 σ discovery --- 152-174 150-176 138-220 120-570 If the Higgs is not there  LHC needs ~ 2.5 fb-1 to compete with Tevatron for exclusion down to lowest masses • If the Higgs exists: • Need 5 fb-1 to compete with Tevatron for 3σ evidence around mH ~ 115 GeV, • but has better sensitivity at higher masses (above ~ 120 GeV) already with 1-3 fb-1 • Discovery (5σ) over full allowed mass region requires ~ 7 fb-1 at 8 TeV Note on 8 TeV vs 7 TeV: -- same reach with ~20% less luminosity -- for same luminosity, extend low-mass reach down by ~ 3 GeV

  17. CONCLUSIONS ATLAS Control Room, 20 November 2009 A fantastic year, exceeding all expectations !! • 2011: the year of first discoveries ? Z’, W’, SUSY, surprises … ? • The Higgs is within reach in the next 1-2 year(s), but the “race” with • the Tevatron will be tough (GeV by GeV, fb-1 by fb-1 …)

  18. Spares

  19. Max peak luminosity: L~ 2 x 1032 cm-2s-1 • average number of pp interactions per bunch-crossing: up to 4 • “pile-up” (~ 80% of the events have > 1 pp interaction per crossing) Event with 4 pp interactions in the same bunch-crossing ~ 10-45 tracks with pT >150 MeV per vertex Vertex z-positions : −3.2, −2.3, 0.5, 1.9 cm (vertex resolution better than ~200 μm)

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