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