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Andrea VenturaAndrea VenturaUniversity of Salento & INFN LecceUniversity of Salento & INFN Lecce
on behalf of the on behalf of the ATLAS CollaborationATLAS Collaboration
New Trends in High-Energy PhysicsNew Trends in High-Energy Physics
Alushta, Crimea, Ukraine, September 5, 2011Alushta, Crimea, Ukraine, September 5, 2011
Lecce
05/09/2011 A. Ventura - ATLAS overview
The The LHCLHC is a proton-proton collider running since is a proton-proton collider running since March 2010 at March 2010 at 7 TeV 7 TeV center-of-mass energycenter-of-mass energy
ATLASA Toroidal LHC ApparatuS
LHCLHC presently presently (Summer 2011)(Summer 2011):: Peak luminosity Peak luminosity
2.4·102.4·103333cmcm-2-2ss-1-1
>1000 bunches >1000 bunches colliding in colliding in ATLASATLAS
50 ns bunch 50 ns bunch spacingspacing
5.7 collisions per 5.7 collisions per bunch crossingbunch crossing
2
30003000 scientists and scientists and 10001000 students from students from 174174 institutions in institutions in 3838 countries: countries: Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Albany, Alberta, NIKHEF Amsterdam, Ankara, LAPP Annecy, Argonne NL, Arizona, UT Arlington, Athens, NTU Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, UAN Athens, Baku, IFAE Barcelona, Belgrade, Bergen, Berkeley LBL and UC, HU Berlin, Bern, Birmingham, UAN Bogota, Bologna, Bonn, Boston, Brandeis, Brasil Cluster, Bratislava/SAS Kosice, Brookhaven NL, Buenos Bogota, Bologna, Bonn, Boston, Brandeis, Brasil Cluster, Bratislava/SAS Kosice, Brookhaven NL, Buenos Aires, Bucharest, Cambridge, Carleton, CERN, Chinese Cluster, Chicago, Chile, Clermont-Ferrand, Columbia, Aires, Bucharest, Cambridge, Carleton, CERN, Chinese Cluster, Chicago, Chile, Clermont-Ferrand, Columbia, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, SMU Dallas, UT Dallas, DESY, Dortmund, NBI Copenhagen, Cosenza, AGH UST Cracow, IFJ PAN Cracow, SMU Dallas, UT Dallas, DESY, Dortmund, TU Dresden, JINR Dubna, Duke, Edinburgh, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, TU Dresden, JINR Dubna, Duke, Edinburgh, Frascati, Freiburg, Geneva, Genoa, Giessen, Glasgow, Göttingen, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima IT, Indiana, Innsbruck, Göttingen, LPSC Grenoble, Technion Haifa, Hampton, Harvard, Heidelberg, Hiroshima IT, Indiana, Innsbruck, Iowa SU, Iowa, UC Irvine, Istanbul Bogazici, KEK, Kobe, Kyoto, Kyoto UE, Lancaster, UN La Plata, Lecce, Iowa SU, Iowa, UC Irvine, Istanbul Bogazici, KEK, Kobe, Kyoto, Kyoto UE, Lancaster, UN La Plata, Lecce, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Lisbon LIP, Liverpool, Ljubljana, QMW London, RHBNC London, UC London, Lund, UA Madrid, Mainz, Manchester, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Manchester, CPPM Marseille, Massachusetts, MIT, Melbourne, Michigan, Michigan SU, Milano, Minsk NAS, Minsk NCPHEP, Montreal, McGill Montreal, RUPHE Morocco, FIAN Moscow, ITEP Moscow, MEPhI Moscow, Minsk NCPHEP, Montreal, McGill Montreal, RUPHE Morocco, FIAN Moscow, ITEP Moscow, MEPhI Moscow, MSU Moscow, LMU Munich, MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, MSU Moscow, LMU Munich, MPI Munich, Nagasaki IAS, Nagoya, Naples, New Mexico, New York, Nijmegen, Northern Illinois, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Olomouc, Oregon, LAL Northern Illinois, BINP Novosibirsk, Ohio SU, Okayama, Oklahoma, Oklahoma SU, Olomouc, Oregon, LAL Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, NPI Petersburg, Pisa, Pittsburgh, CAS Orsay, Osaka, Oslo, Oxford, Paris VI and VII, Pavia, Pennsylvania, NPI Petersburg, Pisa, Pittsburgh, CAS Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Rome I, Rome II, Rome III, Rutherford Appleton Prague, CU Prague, TU Prague, IHEP Protvino, Regina, Rome I, Rome II, Rome III, Rutherford Appleton Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, South Laboratory, DAPNIA Saclay, Santa Cruz UC, Sheffield, Shinshu, Siegen, Simon Fraser Burnaby, SLAC, South Africa, Stockholm, KTH Stockholm, Stony Brook, Sydney, Sussex, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Africa, Stockholm, KTH Stockholm, Stony Brook, Sydney, Sussex, AS Taipei, Tbilisi, Tel Aviv, Thessaloniki, Tokyo ICEPP, Tokyo MU, Tokyo Tech, Toronto, TRIUMF, Tsukuba, Tufts, Udine/ICTP, Uppsala, UI Urbana, Tokyo ICEPP, Tokyo MU, Tokyo Tech, Toronto, TRIUMF, Tsukuba, Tufts, Udine/ICTP, Uppsala, UI Urbana, Valencia, UBC Vancouver, Victoria, Waseda, Washington, Weizmann Rehovot, FH Wiener Neustadt, Valencia, UBC Vancouver, Victoria, Waseda, Washington, Weizmann Rehovot, FH Wiener Neustadt, Wisconsin, Wuppertal, Würzburg, Yale, YerevanWisconsin, Wuppertal, Würzburg, Yale, Yerevan
05/09/2011 A. Ventura - ATLAS overview 3
ATLAS is a multi-purpose collider detector designed for high precision measurements and for searches beyond the Standard Model.
Physics domain of interest includes: Measurements from QCD processes, B-
physics, W/Z, top, tau, massive di-bosons Higgs searches within and beyond SM New W’/Z’ bosons, SuperSymmetry,
ExtraDimensions and various Exotic Physics scenarios
05/09/2011 A. Ventura - ATLAS overview
Examples of searches for new Examples of searches for new resonances resonances shown here (many more results given by F. Derue F. Derue for SM and N. Ruckstuhl for BSM) 4
05/09/2011 A. Ventura - ATLAS overview
2T solenoid, toroid system (∫Bdl=1-7.5 Tm)2T solenoid, toroid system (∫Bdl=1-7.5 Tm) Tracking in Tracking in |η||η|2.52.5calorimetry in calorimetry in |η||η|4.94.9
5
Design requirements High granularity 4 coverage in solid angle Fast response and readout Radiation hardness
Performance specifications Large acceptance Very good particle ID Precise vertex reconstruction Excellent Jet & Etmiss resolution
05/09/2011 A. Ventura - ATLAS overview
• • Inner trackerInner trackerσ/pσ/pTT 0.038%p0.038%pTT 1.5%⨁1.5%⨁
• • EM calorimeter EM calorimeter σ/E σ/E 10%/√E 0.7%⨁ 10%/√E 0.7%⨁
• • Hadronic calorimeterHadronic calorimeter σ/σ/EE 50%/√E 3%⨁50%/√E 3%⨁
• Muon spectrometerMuon spectrometerΔpΔpTT/p/pTT<10% up to 1 TeV<10% up to 1 TeV
6
05/09/2011 A. Ventura - ATLAS overview
2010
2011
7
In 2010: Proton proton collisions ATLAS recorded 45 pb-1 of pp
collisions at 7 TeV In 2011:
Running since March @ 7 TeV Peak luminosity 2.4·1033cm-2s-1
Up to 200pb-1 collected per week >2.5 fb-1data recorded so far Plan is to possibly reach 4-5 fb-1
before the end of the year Beyond:
LHC will run in 2012 Then, long shutdown and run at
higher energy.
05/09/2011 A. Ventura - ATLAS overview
High data-taking efficiency achieved (>95%)
Operational fractions of single detectors very high (>97%)
Data collected in each analysis depend on the specific detector requirements defined
Inner Trackers Calorimeters Muon detectors Magnets
Pixel SCT TRTLArEM
LAr Had
LAr Fwd
Tile MDT RPC CSC TGC Solenoid Toroid
99.9 99.8 100 89.0 92.4 94.2 99.7 99.8 99.7 99.8 99.7 99.3 99.0
SubdetectorNumber of channels
Approximate operational
fractionPixels 80 M 96.9 %SCT Silicon Strips 6.3 M 99.1 %TRT Transition Radiation Tracker 350 k 97.5%LAr EM Calorimeter 170 k 99.8 %Tile Calorimeter 9800 97.5 %Hadronic Endcap LAr calorimeter 5600 99.6 %Forward LAr Calorimeter 3500 99.8 %LVL1 Calorimeter trigger 7160 99.9 %LVL1 Muon RPC trigger 370 k 99.5 %LVL1 Muon TGC trigger 320 k 100 %MDT Muon Drift Tubes 350 k 99.7 %CSC Cathode Strip Chambers 31 k 97.7 %RPC Barrel Muon Chambers 370 k 97.0 %TGC Endcap Muon Chambers 320 k 98.1 %
8
Flexible trigger menu definition continuosly updated with luminosity
Primary (unprescaled) triggers in 2011 3·1033 cm-2s-1 menu include: Electrons: pT>22 GeV Muons: pT > 20 GeV Jets: pT > 240 GeV EtMiss > 60 GeV (Di)photons : pT > 80 (20) GeV …
Tighter triggers planned for 5·1033 menu
05/09/2011 A. Ventura - ATLAS overview
electronselectrons
muonsmuonsjetsjets
9
Raw data are reconstructed at Tier-0 within 2 days Calibration and Data Quality performed for physics analysis Data are ready for analysis on the Grid within 1 week
05/09/2011 A. Ventura - ATLAS overview
Full number of ATLAS jobs per dayFull number of ATLAS jobs per day
SimulationSimulation
AnalysisAnalysis
March 2011 July 2011
Up to 800k jobs per day are processed on Tier-1 & Tier-2’s Analysis Simulation Reprocessing Various
productions Present results
concern data taken until end-July
10
Good resolution and linearity down to very low pT for electrons
05/09/2011 A. Ventura - ATLAS overview 11
Excellent di-muon mass resolution (about 2% at the Z peak)
Good resolution on EETTmissmiss
tested on a wide range of ΣET (comparison pp and PbPb)ATLAS-CONF-2010-
057
Systematic error on Jet Energy Scale known to < 3% on a wide jet pT range
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-032
12
Good data/MC agreement in di-photon invariant mass spectrum even at very low energy (at 0 mass < 20 MeV)
05/09/2011 A. Ventura - ATLAS overview
SV0 b-tagging algorithm tuned for 40-60% efficiency against 0.2-1% mistag rate for 20 < pT
jet < 150 GeVATLAS-CONF-2010-099
13
For most of 2011 data, 50 ns bunch trains running at LHC
Relevant in-time and out-of-time pileup, with average of <<μμ>=5.7 >=5.7 superimposed events
Distributions of μ for MC in all analyses shown have been reweighted to reproduce data
05/09/2011 A. Ventura - ATLAS overview
Z→μμ event with 11 primary verticesZ→μμ event with 11 primary vertices
14
Cross sections of several SM processes
Theoretical uncertainties calculated at NLO or higher
Significant improvements in precision from 2010 to 2011 data
After many years, deep knowledge of detector performance
05/09/2011 A. Ventura - ATLAS overview
Stat. errorStat+syst.+lumi. error
15
More details on SM results in F. Derue’s talkMore details on SM results in F. Derue’s talk
Many interesting Higgs decay channels under investigation Possible hints are at 120-140 GeV (see N. Rucksthul’s talk)
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-112
H
ATLAS-CONF-2011-111
H WW(*)ll
At the moment, combining all channels and using up to 2.3 fb -1, ATLAS excludes mH in [146,232] [256,282] [296,466] GeV
16
In MSUGRA limits on gluino/squark masses have been significantly increased from 2010 to 2011
05/09/2011 A. Ventura - ATLAS overview
0 leptons channel 1 lepton channel
17
05/09/2011 A. Ventura - ATLAS overview
Di-jet resonancesDi-jet resonances Dilepton resonancesDilepton resonances
e-e- resonances resonances
Some examples of searches for peaks in invariant mass Some examples of searches for peaks in invariant mass distributions are shown in the following slidesdistributions are shown in the following slides
More details on More details on BSM searches in BSM searches in
N. Ruckstuhl’s talkN. Ruckstuhl’s talk18
At least two jets with pT>30GeV, ||<2.8
Searches for peaks in the mjj spectrum
Most relevant excess in [1.16,1.35] TeV (not significant)
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-095
QCD parametrization
BUMPHUNTER tomography
95% CL limit on new physics cross section for simple-gaussian resonance in the region [0.9,4.0] TeV for 4 values of width/mean of mjj
19
Three physics models analyzed No evidence of new physics
found with respect to the expected SM QCD background
05/09/2011 A. Ventura - ATLAS overview
2010 analyses: New J Phys 13 (2011) 053044
ATLAS-CONF-2011-095
Model95% CL Limits (TeV)
Expected Observed
Excited quarks q* 2.77 2.91Axigluons 3.02 3.21Color Octet Scalar 1.71 1.91
20
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-083*
Examined scenarios: Z’ (SSM, E6) Randall-Sundrum graviton Contact interactions
Events with two same-flavor leptons Searches for peaks in the mmllll spectrumspectrum
Main SM background is Z/*ll Excellent agreement Data-MC
21
No evidence found for new physics signal for various BSM models On 2010 also limits determined for
contact interaction dimuon >5.1 TeV Phys Lett B700 (2011) 163-180
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-083*
Model95% CL Limits (TeV)Expected Observed
Z’ (E6) 1.50-1.64 1.50-1.64
Z’ (SSM) 1.83 1.83R-S G, k/M=0.1 1.61 1.63R-S G, k/M=0.01 0.7 0.7
22
Events with exactly 1e + 1μ , isolated and with pT >25 GeV
New improved 95% CL limits on BR for ν̃_ mass in SUSY RPV models and also for heavy neutral gauge boson Z’ with LFV couplings.
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-109
ν̃ ν̃ ττ → → eeμμ
23
05/09/2011 A. Ventura - ATLAS overview
95% CL Lower Limits95% CL Lower Limits
24
ATLAS experiment at LHC has collected so far >2.5 fb-1 and is working very well.
As of now, no definitive evidence of Higgs production, excluded (@ 95% CL) within SM over the region [146,232] [256,282] [296,466] GeV.
More and more stringent mass limits obtained on SUSY and new BSM phenomena.
Now investigating unexplored regions to possibly discover new physics new physics with increased integrated luminosity (possibly 4-5 fb-1 until end of 2011).
05/09/2011 A. Ventura - ATLAS overview 25
05/09/2011 A. Ventura - ATLAS overview 26
Graviton excitations expected in the di-photon spectrum in R-S warped ED models
Backgrounds: SM , jet and multijets
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-044
Number of Extra Dimensions
95% CL Limits (GeV)
Expected Observed
G, k/M=0.02 503 545G, k/M=0.1 975 920
27
Events with only one high-pT jet large Et
miss and no leptons Three sets of thresholds used:
lowPt, highPt, veryHighPt EW background: Z/W +jets
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-096
MC normalized to data in an orthogonal lowPt subsample
Good agreement between data and SM expected bckg. within stat.+syst. errors
28
No evidence found for LED ADD model physics scenarios
Model independent 95% CL limits on A: low/high/veryHighPt : 1.7/0.11/0.035 pb
Limits improved by factors larger than 2 compared to CDFCDF and LEPLEP combined
05/09/2011 A. Ventura - ATLAS overview
ATLAS-CONF-2011-096
Number of Extra Dimensions
95% CL Limits (TeV)
Expected Observed
n=2 2.98 3.16 n=3 2.44 2.56 n=4 2.18 2.27 n=5 2.03 2.10 n=6 1.92 1.99
29