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The LHC the story so far

The LHC the story so far. Alan Barr University of Oxford. PASCOS, July 2011. The Standard Model. Fields (Maxwell, Weak, Strong). Fermions (Dirac…). Masses & potentials. (Untested). + other terms?. The accelerator…. 1232 x 14.3 m dipoles

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The LHC the story so far

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  1. The LHC the story so far Alan BarrUniversity of Oxford PASCOS, July 2011

  2. The Standard Model Fields (Maxwell, Weak, Strong) Fermions (Dirac…) Masses & potentials. (Untested) + other terms?

  3. The accelerator… 1232 x 14.3 m dipoles Superconducting Superfluid (1.9K)Liquid Helium Cooled 7 TeV CM energy 14 TeV ~1 GJ Magnetic Energy ~100 MJ Beam Energy 1 MJ melts 1.5 kg Cu

  4. 2 x general-purpose experiments energy, momentum, identification controlled environment ~ 109 collision / second ~ decade of operation LHCb ATLAS ALICE CMS

  5. ATLAS Segment of 4π detector

  6. Local Interest: ATLAS Semiconductor Tracker… Cambridge: Silicon R&D, testing Robotic assembly

  7. A year is a long time at the LHC Commissioned bunch trains 50 ns bunch-crossing operation

  8. 1 fb-1 target PASCOS 2010  0.0002 fb-1

  9. Sure things @ TeV-scale ~ 100 physics publications on collision data from CMS + ATLAS Strong interaction Weak interaction Higgs Sector or other Electroweak SB Flavours 3rdgeneration quarks (t and b) CP violation

  10. ATLAS Strong interactions • Self-interacting force carriers • Perturbative regime • Jets of hadrons • Radiation from accelerated colour • Backgrounds to all other searches • Non-perturbative • Quark-gluon plasma • Nucleon structure

  11. CMS-QCD-10-011 Agreementover 10 decades NLO Monte Carlo DATAdeconvolved Uncertaintiesin Jet EnergyScale understood

  12. ATLAS-CONF-2011-081 Dijets @ muliti-TeV CM Energy = 4 TeV ATLAS

  13. Strong interactions – papers Inelastic cross section Jet cross sections Jet shapes Dijet azimuthal decorrelations Dijet resonances Underlying event Charged hadron distributions Bose-Einstein correlations Strong contact interactions Event shapes

  14. Weak interactions WW ZZ Masses and couplings well known Self-interactions under study Cross-sections diverge without new physics

  15. Electroweak cross sections

  16. ATLAS-CONF-2011-060 W + Jets Electroweak + strong radiation Background to many searches Test MC simulations

  17. Excludes SM-like Z’ M<1.41 TeV After you understand the Z… ATLAS-CONF-2011-083

  18. Higgs sector – the model LHC sensitivity to almost all SM Higgs masses 2011-12 Field couples to mass Scalar potential Vacuum expectation value W, Z masses via Higgs/gauge interactions Fermion masses via Higgs/Yukawa coupling Field excitation = Higgs boson(s)

  19. Higgs boson production and decay • Coupling  mass • Production • Gluon fusion • Weak boson fusion • Decay • To heaviest allowed states

  20. arXiv:1106.2748 15 June: full ATLAS search Higgs analysis of 2010 data

  21. Higgs  WW (search)

  22. Higgs search status

  23. CMS-PAS-HIG-10-002 Higgs   (search)

  24. 3rd Generation: t and b Three generations needed for CP violation Nearly decoupled from first two generations Long lived b-quark hadrons Standard Model: top Higgs coupling ~unity Radiative corrections from top on mH Role in electroweak symmetry breaking?

  25. Papers (flavour) arXiv:1106.0902 • Cross sections • and single • mass of top • jets • Upsilon () • J/Psi () • Strange

  26. ATLAS-CONF-2011-087

  27. More speculative (perhaps?)… Further generations Unification of forces Supersymmetry WIMPs Compositeness / substructure New gauge forces / particles Strong gravity Extra dimensions Something else?

  28. Physics Beyond the Standard Model New results with 2011 data

  29. Supersymmetry Partner particles Spin differ by ½ Stabilise mH Dark Matter candidates “Missing” momentum Big reach at LHC

  30. Supersymmetry searches 25 Feb 2011 ATLAS-CONF-2011-086 arXiv:1106.5048 “Missing” momentum Scalar sum of momentum

  31. Interpretation ATLAS-CONF-2011-086 Simplified model Squark, gluino, massless neutralino Exclude mq = mg< 1.02 TeV Degenerate points harder

  32. Wider interpretation... ATLAS 0/1 leptonATLAS-CONF-2011-086 H  CMS αT June’11 h Jan’11 Cassel, Ghilencea, Kraml, Lessa, Ross http://arxiv.org/abs/1101.4664 Allanach, Khoo, Lester, Williams http://arxiv.org/abs/1103.0969 Regions with low fine tuning Points sampled from fits to global data Global CMSSM fits Alan Barr, University of Oxford

  33. Getting the results? • ATLAS • Public results: link • CMS • Public results: link • Recent conference • Physics at the LHC 2011, ;link • Upcoming new results: • EPS 2011, 21-27 July; link

  34. Conclusions • Excellent operation of LHC and detectors • > 1 fb-1 • Remarkable degree of control • New Physics Searches leading the world • Supersymmetry / WIMPs • Resonances • Substructure • … • Sufficient data for Higgs search • Over wide range of SM cross-sections • Full range by end 2012?

  35. LHC PHYSICS Extra slides

  36. 2011 Plans…

  37. Software Operations Hardware Grid Detector & Upgrade Computing

  38. http://indico.cern.ch/conferenceDisplay.py?confId=100963

  39. Large Hadron Collider 1 MJ melts 1.5 kg Cu

  40. W charge asymmetry Vector – Axial couplings (Chiral couplings) Probe proton structure (Parton distributions) Cancellation of systematic uncertainties

  41. Pileup • The pileup in 2011 is on average <μ>=6 interactions per crossing • Significantly higher than 2010 • And than originally anticipated in early LHC running • Tails up to 14 interactions per crossing • Due to some bunches with much higher currents • Causes challenge for physics analyses and software • Detailed simulation models both the <μ> and the bunch train structure • Reweighted according to data <μ> distribution • Software performance significantly improved to accommodate Tier0 resources (reco time 11-13s/event) • Physics performance reasonably unaffected • Jet energy scale uncertainty temporarily increased for low pT jets

  42. Summary of Electroweak Boson and Top Quark Cross Sections • All measurements agree with SM expectation (so far) • Measuring cross sections of ~10 pb

  43. Further search papers • Others • Monojets • e-mu resonances • Dilepton resonances • Leptoquarks • CHAMPS • Dimuons (contact) • W' l  • Z'  ll • Supersymmetry: • Squarksor gluinos • Lepton + jet + invis • Dilepton + invis • Same sign leptons + invis • Z + invis • b-jet(s) + invis • R-hadrons

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