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Energy Frontier High Energy Physics The LHC Project

V2 (2009.3.1). Energy Frontier High Energy Physics The LHC Project. February 18, 2009 Takahiko Kondo KEK, Professor Emeritus First International Winter School of the Global COE on the Quest of Fundamental Principle in Universe, Nagoya University, at Kintetsu Aqua Villa Ise-Shima.

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Energy Frontier High Energy Physics The LHC Project

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  1. V2 (2009.3.1) Energy Frontier HighEnergy Physics The LHCProject February 18, 2009 Takahiko Kondo KEK,Professor Emeritus First International Winter School of the Global COE on the Quest of Fundamental Principle in Universe, Nagoya University, at Kintetsu Aqua Villa Ise-Shima Original file at : http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pdf http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pptx

  2. Congratulations for the Nobel Prize in Physics 2008 !

  3. Spontaneous Symmetry Breaking • Example: Ferromagnetic material • Equation of motion is symmetric under rotation, with no specific direction. • Above TC (Curie Temp.) paramagnetic. • Below TC , a specific direction is chosen spontaneously. • World of elementary particles • Equation is symmetric under gauge transformation (= internal symmetry). • Above ~1 TeV, the vacuum is symmetric. • Below ~1 TeV , the vacuum (= ground state) has a non-zero Higgs field spontaneously.

  4. 1869 Number of basic elements: 63 (year 1869) ↓ 12 (year 1995) ↓ 1 (year 2xxx ?) 1995

  5. Four forces (interactions) All forces are generated by the exchange of gauge bosons Gauge boson Force : Strong Electro-Magnetic Weak Gravity Gauge boson: gluonphoton W, Z graviton spin: 1 1 1 2 Standard Model (based on gauge-invariant Quantum Field Theory)

  6. Fundamental problems [1] How to avoid infinity in calculations? Infinite number of higher order terms must be summed and usually you get ! [2] Why bare quarks never come out ? My first experiment in graduate course (~1967) was to search for 1/3e particles in cosmic rays. No bare quarks found so far. But nucleons are made out of three quarks. proton neutron [3] Why W,Z bosons and quarks/leptons have mass? Gauge-invariance (with parity violation) prohibits mass of particles. However, mW~81 GeV, mZ~91GeV, mt~172 GeV, me=0.55 MeV. (Note:Without gauge-invariance, infinity problem (1) cannot be solved.) Nobel prizes were awarded to the solvers of each problem !

  7. Solution for [1] : Quantum Electro Dynamics（QED) In 1940s , a renormalization method （くりこみ法）was developed successfully to avoid the infinities, making high precision predictions possible. e.g. anomalous magnetic moment Renormalization is possible because QED is gauge invariant. Theory must be local gauge invariant . 1965 TomonagaFeynmannSchwingers "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles” Local gauge invariance h h h (x3 y3 z3) (x1 y1 z1) x x x (x2 y2 z2) Theory is invariant under arbitrary rotations of internal coordinates.

  8. Solution for [2] : Quantum Chromo Dynamics (QCD) • Quarks have 3color charges. • Gluons of 8colors carry force. • Particles (π,p, n….) have no color. • Asymptotic freedom: Force is like rubber band. Smaller as closer, stronger as farther. 2004 D. Gross H.D. Politzer F. Wilczek "for the discovery of asymptotic freedom in the theory of the strong interaction" If one tries to separate two quarks by force, quark pairs (e.g. d, dbar) is created from vacuum since it is energetically smaller. Thus bare quarks never come out.

  9. Solution for [3] : Glashow-Weinberg-Salam Model • Electroweak symmetry SU(2)L and weak-hypercharge symmetry U(1)Y exists at higher energies. • They are spontaneouslybroken by a Higgs field. 3 gauge bosons become massive by eating 3 Higgs fields. • At least one Higgs particle must exist. • Quarks/leptons can be massive. 1979 S. Glashow S. Weinberg A. Salam "for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current" Spontaneous Symmetry Breaking

  10. Glashow-Weinberg-Salam Theory [1] S. Wenberg, Phys. Rev. Lett. 19 (1967) 1264

  11. R.BroutF. Englert P. Higgs GWS model is renomalizable • In 1971, ‘t Hooft proved GWS model is renormalizable. • Discovery of neutral current in 1973 at CERN. • ep scattering experiment at SLAC proved the GWS model in 197 D ‘t Hooft M. Veltman 1999 "for elucidating the quantum structure of electroweak interactions in physics" Why it is called Higgs particle ? In 1964, several theorists independently pointed that mass-less gauge bosons become massive when the symmetry breaks down spontaneously in the presence of self-coupling scalar field, mathematically. Weinberg and Salam applied their findings in the electroweak theory.

  12. Predictions by Standard Model Total hadronic cross section of the e-e+ annihilation process Standard model Standard Model predicts all the processes from ~ 1eV through 100,000,000,000 eV level with very high precisions. No phenomenon against Standard Model is found so far (except DM).

  13. Standard Model : SU(3)C×SU(2)L×U(1)Y Higgs particles is the only missing element to be discovered. All other elements were discovered in 20th Century.

  14. Properties of SM Higgs Particles • Higgs mass mH is a free parameter. Most likely 100 ~ 1000 GeV. • Search at LEP  mH > 114.4 GeV • Search at Tevatron mH≠ 170 GeV • Indirect measurements via quantum corrections  mH < 144 GeV • The main goal of the LHC project is to discover the Higgs particles. (yellow) excluded by direct search. (blue) probability via SM radiative quantum corrections. Higgs simulation at LHC: pp → H → Z Z → μ+μ-μ+μ- (yellow tracks).

  15. CERN CERN Founded in1954, 20 member countries, 2500 staffs, 9000 users annual budget 1,000 MCHF Invention of WWW in 1990. CERN Geneva

  16. LHC (Large Hadron Collider) Circumference 26.6 km major experiments ATLAS CMS ALICE LHCb Approved in 1994 Completed in 2008 Cost : 10B$

  17. LHC accelerator and Detectors C M S tunnel 26.6 km pp energy 7+7 TeV luminosity 1034 cm-2s-1 dipole magnets8.33T, 1232 ALICE LHCb ATLAS

  18. Video: Construction of LHC(magnetToRing.wmv)

  19. Superconducting Magnet 2 beam in 1 magnet Cool down to 1.9K Magnetic field 8.33 Tesla 1232 dipole superconducting dipole magnet bends the beam.

  20. ATLAS Experiment • A general purpose detector for pp collision to search for Higgs and new. • International collaboration of 2,200 scientists, from 37 countries (incl. Japan). • Height 25m, length 44m, eight 7000 t . • Construction cost : about 550 MCHF. Construction took 14 years. • > 80,000,000 signal channels. • 15 Japanese institutes (incl. Nagoya) contributes in Muon trigger Superconducting solenoid Silicon detector Major contribution by Japan

  21. ATLAS detector under construction at November 2005

  22. ATLAS : example of contribution by Japan EndcapMuon trigger system (Japan, Israel and China) 1200 chamber production at KEK (2000-2004) 320K channels of electronics at KEK Nagoya U. N group Cosmic-ray test at Kobe Univ. Assembly at CERN (2005-2007) Installation at underground hall (2006-2008）

  23. Construction of ATLAS(ATLAS_construction.wmv)

  24. First beam in the LHC 10 Sep. 2008 Proton beam of 450 GeV successfully went around the LHC ring in 50 min. with live broadcasting to the whole world.

  25. The beam orbit is measured on-line by position monitors with instant feedback actions. Beam successfully went 1 turn clock-wise within 50 min. of injection start. Next day, the beam was synchronously captured by RF cavity resulting several undred turns. ATLAS observed many muons created upstream by the proton beam.

  26. He leak incident on 19 Sept. 2008 • 9 days after, a large He leak occurred during power test of sector 34, the last sector that should have been tested before 10 Sept. • One (out of >10,000) connection btwn two magnets melted down, causing He leak of 6 tons. Evaporated He gas damaged and moved many magnets. • After investigation, 53 magnets were removed to surface for repair. • Much better safety measures are being taken to prevent similar incidents. • The beam test will resume in Sept. 2009. 5+5 TeV physics runs will start in Oct. 2009 and continue till the 2010 fall. A cable connection melted down causing large He leak. Some magnets moved due to He gas pressure.

  27. Higgs discovery at LHC • s(production) and decay branchin rations are well predicted as a function of mH. • Main decay modes for discovery: • Data taking will start in Oct. 2009 (hopefully) at ECMS = 10 TeV. Reconstruction of H→gg 2012(?) 2011(?) 2010 (?) (red) 5sdiscovery line (blue) 95% excllusion line

  28. Hierarchy (fine tuning, naturalness ) problem H H • Higgs particles get large quantum mass corrections (because it is scalar) mH = 200 GeV dmH = 1,000,000,000,000,000,000 GeV if next new physics were at ~1019GeV (Planck scale). This is very unnatural. Solution 1 :SUSY If SUSY particles exist, the quadratic mass correction term exactly cancel out. Solution 2 : Extra Dimensions The next new physics exists at 1~10 TeV. Quantum corrections on mH H H Quantum corrections by SUSY particles

  29. SUSY (Super Symmetry) Symmetry between fermions (half spin) and bosons (integer spin) No SUSY particles are found so far  SUSY must be broken softly.

  30. Running coupling constants + + + + + + + + - - - - - - - - + Shielding by vacuum polarization in QED q clouds of gluons & quarks Anti-shielding by vacuum polarization in QCD if nq< 33/2 Coupling constants varies as a function of energy (distance). QED : shielding (stronger as E↑） QCD : anti-shielding (weaker as E↑） due to gluon self-coupling

  31. GUT (Grand Unification Theory) Three forces may be unified at 2x1016GeV if SUSY particles exist at 1 TeV. note: based on RGE equations given by U. Amaldi et al., Phys. Lett. B260(1991)447. data for 1/a1 are scaled from 1/aEMby 3/5*cos2qW

  32. Dark Matter (DM) rotation of galaxy dark matter map using gravity lens motion of galactic cluster Standard Model explains only 4% of our Universe ! ! colliding galaxy cluster 3K microwave background

  33. Thermodynamics in expanding universe with cold DM scenario within reach of LHC !! Standard Model Dark Matter candidate: Neutralinos SUSY (MSSM) to be discovered

  34. Detection of DM at LHC • SUSY particles carry R-parity = -1: • Because of R-parity, LSP (lightest supersymmetricparticle) is neutral, stable and be intact with matter, a good DM candidate! • LSP escapes from the detector leaving large missing Et. detector p SUSY particle production at LHC. p (LSP) Simulated SUSY event in CMS detector

  35. Large Extra Dimension New approach to solve the hierarchy problem 1016 Electro-weak scale Planck scale 3 forces gravity in 4+2 extra dimensions Newton gravity F ~ 1/r2 Gravity extends to large bulk, while SM stays on 4-dim brane. Interaction energy

  36. LHC will reach back to 10-12 secafter the Big Bang.

  37. from E. Kolb and M. Turner p.73 History of Universe QUANTUM END OF END OF MATTER● Formation GRAVITY GRAND ELECTROWEAK DOMINATION of Atoms ● Supergravity?UNIFICATION UNIFICATION● Formation of ● Decoupling of - ● Ex Dim?● Origin of Matter- ● End of SUSY? Quark Hadron Structure begins Matter and ● Supersymmetry? Antimatter Symmetry Transition Big Bang ● Superstrings? ● MonplolesNucleosynthesis ● Inflation B I G B A N G Rest Energy KE of Highest energy CM Energy Nuclear Binding Atomic of Flea Sprinter Cosmic rays of LHC Energy Binding Energy 1 103 106 109 Years 2K n bkgd Leptons & Quarks Gauge Bosons Photons R(matter/radiation)=5x10-10 3K CMB

  38. from E. Kolb and M. Turner p.73 History of Universe QUANTUM END OF END OF MATTER● Formation GRAVITY GRAND ELECTROWEAK DOMINATION of Atoms ● Supergravity?UNIFICATION UNIFICATION● Formation of ● Decoupling of - ● Ex Dim?● Origin of Matter- ● End of SUSY? Quark Hadron Structure begins Matter and ● Supersymmetry? Antimatter Symmetry Transition Big Bang ● Superstrings? ● MonplolesNucleosynthesis ● Inflation B I G B A N G Rest Energy KE of Highest energy CM Energy Nuclear Binding Atomic of Flea Sprinter Cosmic rays of LHC Energy Binding Energy 1 103 106 109 Years 2K n bkgd Leptons & Quarks Gauge Bosons Photons R(matter/radiation)=5x10-10 3K CMB LHC could elucidate this region

  39. Summary • Standard Model describes all the phenomena with high accuracy . • Spontaneous Symmetry Breaking must exist to explain the masses of W, Z and quarks/leptons. Higgs particle must exist. • LHC accelerator and detectors ATLAS and CMS has just completed aiming at Higgs discovery. • Higgs will be discovered in a few years of LHC operation. • If LHC discover SUSY, hierarchy problem be solved, Grand Unification may become likely and dark matter may be explained. • New results from LHC may extend our understandings on fundamental principles from 100 GeV to1 possibly 1016GeV, corresponding to 10-11 to 10-38sec after the Big Bang.

  40. Some useful introduction references with more details:1) Lecture at the 2008 summer school for young students (日本語)http://atlas.kek.jp/sub/OHP/2008/20080820Kondo.ppt http://atlas.kek.jp/sub/OHP/2008/20080820Kondo.pdf2) Introduction to physics calculations and histrogramming(日本語) http://atlas.kek.jp/seminar課題１：パイオンの崩壊からニュートリノビームを作る課題２：陽子の中のクォークとグルーオンの分布課題３：ヒッグス粒子の崩壊比と生成断面積を計算する課題４：高エネルギーイベントのシミュレーション課題５：Running Coupling Strengthsを計算する課題６：Geant4による電磁シャワーのシミュレーション→ may be useful for Minima B3) ATLAS Japan groupHP (日本語)http://atlas.kek.jp4) LHC加速器の現状とCERNの将来計画(近藤)http://www.jahep.org/hepnews/2008/Vol27No3-2008.10.11.12Kondo.pdf

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