Slide 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 1 Original file at :http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pdf http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pptx V2 (2009.3.1)

Slide 2

Congratulations for the Nobel Prize in Physics 2008 ! Yoichiro NambuMakoto KobayashiToshihide Maskawa 1/2 of the prize1/4 of the prize "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics" "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature" Experimentally confirmation is not yet completed ! Experimentally three families and CP violation were confirmed. 2

Slide 3

Spontaneous Symmetry Breaking Example: Ferromagnetic material -Equation of motion is symmetric under rotation, with no specific direction. -Above T C (Curie Temp.) paramagnetic. -Below T C, 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. 3

Slide 4

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

Slide 5

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

Slide 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, m W ~81 GeV, m Z ~91GeV, m t ~172 GeV, m e =0.55 MeV. (Note:Without gauge-invariance, infinity problem (1) cannot be solved.) Nobel prizes were awarded to the solvers of each problem ! 6

Slide 7

7 Solution for [1] : Quantum Electro DynamicsQED) Tomonaga Feynmann Schwingers In 1940s, a renormalization method 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. "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles 1965 (x 1 y 1 z 1 ) (x 2 y 2 z 2 ) (x 3 y 3 z 3 ) Local gauge invariance Theory is invariant under arbitrary rotations of internal coordinates.

Slide 8

Solution for [2] : Quantum Chromo Dynamics (QCD) D. Gross H.D. Politzer F. Wilczek Quarks have 3 color charges. Gluons of 8 colors carry force. Particles (,p, n.) have no color. Asymptotic freedom: Force is like rubber band. Smaller as closer, stronger as farther. "for the discovery of asymptotic freedom in the theory of the strong interaction" 2004 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. 8

Slide 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 spontaneously broken 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. 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" 1979 Spontaneous Symmetry Breaking 9

Slide 10

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

Slide 11

11 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 "for elucidating the quantum structure of electroweak interactions in physics" 1999 D t Hooft M. Veltman R. Brout F. Englert P. Higgs 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. GWS model is renomalizable

Slide 12

Predictions by Standard Model 12 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). Total hadronic cross section of the e - e + annihilation process Standard model

Slide 13

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

Slide 14

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

Slide 15

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

Slide 16

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

Slide 17

17 ATLAS C M S ALICE tunnel26.6 km pp energy7+7 TeV luminosity10 34 cm -2 s -1 dipole magnets8.33T, 1232 LHCb LHC accelerator and Detectors

Slide 18

Video: Construction of LHC (magnetToRing.wmv) 18

Slide 19

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

Slide 20

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 Silicon detector Superconducting solenoid Major contribution by Japan

Slide 21

21 ATLAS detector under construction at November 2005

Slide 22

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

Slide 23

Construction of ATLAS (ATLAS_construction.wmv) 23

Slide 24

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

Slide 25

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

Slide 26

26

Slide 27

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. 27 He leak incident on 19 Sept. 2008 A cable connection melted down causing large He leak. Some magnets moved due to He gas pressure.

Slide 28

28 Reconstruction of H Higgs discovery at LHC 2010 (?) 2011(?) 2012(?) (production) and decay branchin rations are well predicted as a function of m H. Main decay modes for discovery: Data taking will start in Oct. 2009 (hopefully) at E CMS = 10 TeV. (red) 5 discovery line (blue) 95% excllusion line

Slide 29

Hierarchy (fine tuning, naturalness ) problem Higgs particles get large quantum mass corrections (because it is scalar) m H = 200 GeV m H = 1,000,000,000,000,000,000 GeV if next new physics were at ~10 19 GeV (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. 29 Quantum corrections on m H H H H H Quantum corrections by SUSY particles

Slide 30

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

Slide 31

q + 31 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 Shielding by vacuum polarization in QED Running coupling constants - + - + - + - + - + - + - + - + Anti-shielding by vacuum polarization in QCD if n q < 33/2 clouds of gluons & quarks

Slide 32

32 GUT (Grand Unification Theory) Three forces may be unified at 2x10 16 GeV 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/ 1 are scaled from 1/ EM by 3/5*cos 2 W

Slide 33

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

Slide 34

34 to be discovered Dark Matter candidate: Neutralinos within reach of LHC !! Thermodynamics in expanding universe with cold DM scenario

Slide 35

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

Slide 36

Large Extra Dimension New approach to solve the hierarchy problem Interaction energy 3 forces gravity in 4+2 extra dimensions Electro-weak scalePlanck scale 10 16 Newton gravity F ~ 1/r 2 Gravity extends to large bulk, while SM stays on 4-dim brane. 36

Slide 37

LHC will reach back to 10 -12 sec after the Big Bang. 37

Slide 38

38 Rest EnergyKE ofHighest energyCM EnergyNuclear BindingAtomic of FleaSprinterCosmic rays of LHCEnergyBinding Energy QUANTUMEND OFEND OFMATTER Formation GRAVITYGRANDELECTROWEAKDOMINATION of Atoms Supergravity? UNIFICATIONUNIFICATION Formation of Decoupling of - Ex Dim? Origin of Matter- End of SUSY? Quark HadronStructure begins Matter and Supersymmetry?Antimatter SymmetryTransitionBig Bang Superstrings? MonplolesNucleosynthesis Inflation History of Universe from E. Kolb and M. Turner p.73 Leptons & Quarks Gauge Bosons Photons R(matter/radiation)=5x10 -10 3K CMB 2K bkgd 1 10 3 10 6 10 9 Years

Slide 39

39 Rest EnergyKE ofHighest energyCM EnergyNuclear BindingAtomic of FleaSprinterCosmic rays of LHCEnergyBinding Energy QUANTUMEND OFEND OFMATTER Formation GRAVITYGRANDELECTROWEAKDOMINATION of Atoms Supergravity? UNIFICATIONUNIFICATION Formation of Decoupling of - Ex Dim? Origin of Matter- End of SUSY? Quark HadronStructure begins Matter and Supersymmetry?Antimatter SymmetryTransitionBig Bang Superstrings? MonplolesNucleosynthesis Inflation History of Universe from E. Kolb and M. Turner p.73 Leptons & Quarks Gauge Bosons Photons R(matter/radiation)=5x10 -10 3K CMB 2K bkgd 1 10 3 10 6 10 9 Years LHC could elucidate this region

Slide 40

40 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 10 16 GeV, corresponding to 10 -11 to 10 - 38 sec after the Big Bang. Summary

Slide 41

Some useful introduction references with more details: 1) Lecture at the 2008 summer school for young students () http://atlas.kek.jp/sub/OHP/2008/20080820Kondo.ppt http://atlas.kek.jp/sub/OHP/2008/20080820Kondo.pdf 2) Introduction to physics calculations and histrogramming () http://atlas.kek.jp/seminar Running Coupling Strengths Geant4 may be useful for Minima B 3) ATLAS Japan group HP () http://atlas.kek.jp 4) LHCCERN() http://www.jahep.org/hepnews/2008/Vol27No3-2008.10.11.12Kondo.pdf 41