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
Original file at :
http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pdf
http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pptx
1
Congratulations for the Nobel Prize in Physics 2008 !
Yoichiro Nambu
Makoto Kobayashi
Toshihide Maskawa
1/2 of the prize
1/4 of the prize
1/4 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
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.

V
2
V
 174 GeV
2
- Below ~1 TeV , the vacuum (= ground state)
has a non-zero Higgs field spontaneously.
3
1869
Number of basic elements:
63 (year 1869)
↓
12 (year 1995)
↓
1 (year 2xxx ?)
1995
4
Four forces (interactions)
All forces are generated by the
exchange of gauge bosons
Force :
Strong
Gauge boson:
spin:
gluon
1
Electro-Magnetic
photon
1
Gauge boson
Weak
Gravity
W, Z
1
graviton
2
Standard Model
(based on gauge-invariant Quantum Field Theory)
5
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 !
6
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.
Tomonaga Feynmann Schwingers
e.g. anomalous magnetic moment
ae 
g 2
 0.00115965218085　(exp.)
2
 0.00115965218870 (theory)
Renormalization is possible because QED
is gauge invariant.
Theory must be local gauge invariant .
1965
"for their fundamental work in
quantum electrodynamics, with
deep-ploughing consequences
for the physics of elementary
particles”
Local gauge invariance
h
(x1 y1 z1)
x
(x3 y3 z3)
(x2 y2 z2)
Theory is invariant under arbitrary
rotations of internal coordinates.
 ( x)  eiq ( x ) ( x)
7
Solution for [2] : Quantum Chromo Dynamics (QCD)
• Quarks have 3 color charges.
• Gluons of 8 colors carry force.
• Particles (π,p, n….) have no color.
• Asymptotic freedom: Force is like
D. Gross
rubber band. Smaller as closer,
stronger as farther.
2004
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.
8
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.
W
1
W
2
W
m=0
m=0
m=0
1
2
3
3
B
"for their contributions to the
theory of the unified weak and
electromagnetic interaction
between elementary particles,
1979 including, inter alia, the prediction
of the weak neutral current"
_
0
W W Z
mW mW mZ
+
m=0
4
S. Glashow S. Weinberg A. Salam
Spontaneous
Symmetry
Breaking
m=0
mH
9
Glashow-Weinberg-Salam Theory


 

2
2
1 
1
L  L i  D L  R i  D R  W   W  B  B  D    2 †    †  Ge R  †L  L R
4
4
 
 
1
where D     ig2W   ig1 B Y , B   B    B , L   e  , R  eR
2
2
 e L

SU(2)L : L
 
i  ( x )
e 2
L,




1
R  R, W  W    ( x)   ( x)  W , B  B
g2


1
U(1)Y : L  ei ( x )Y L, R  ei ( x )Y R, W  W , B  B     ( x)
g1
 Z   cos W  sin  W W3 
 ,
   
 A   sin  W cos W  B 
g2 
e
e
, g1 
sin  W
cos  W
after Supontaneous Symmetry Breaking : SU (2) L  U (1)Y  U (1)Q ,  ( x) 

1  0 

　2   h ( x ) 

1
g 22
4h 3 h 4 
2 1 2  
2 1
2 1
2 2 1 2 2
L  h   g 2W W   h  
ZZ   h    2  h     1  3  4   Gee e  Ge he e
2
4
8 cos2 W
2
4

 

m
1
1 g2
therefore　mW  g 2 , mZ 
  W , mH  2  , me  Ge ,  
2
2 cosW
cosW
[1] S. Wenberg, Phys. Rev. Lett. 19 (1967) 1264
10
1
 246 GeV
2GF
GWS model is renomalizable
• In 1971, ‘t Hooft proved GWS model is
renormalizable.
D ‘t Hooft
• Discovery of neutral current in 1973 at CERN.
• ep scattering experiment at SLAC proved the
GWS model in 197
1999
M. Veltman
"for elucidating the
quantum structure of
electroweak interactions
in physics"
Why it is called Higgs particle ?
R. Brout
F. Englert
P. Higgs
In 1964, several theorists independently
pointed that mass-less gauge bosons
become massive when the symmetry breaks
down spontaneously in the presence of selfcoupling scalar field, mathematically.
Weinberg and Salam applied their findings in
the electroweak theory.
11
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).
12
Standard Model : SU(3)C×SU(2)L×U(1)Y
mgluon  0
m  0
mW  80 GeV
mZ  91 GeV
Higgs particles is the only missing element to be discovered.
All other elements were discovered in 20th Century.
13
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
(yellow) excluded by direct search.
(blue) probability via SM radiative
quantum corrections.
• The main goal of the LHC project is to
discover the Higgs particles.
Higgs simulation at LHC: pp → H →
Z Z → μ+μ-μ+μ- (yellow tracks). 14
CERN
CERN
Founded in1954,
20 member countries,
2500 staffs, 9000 users
annual budget 1,000 MCHF
CERN
Geneva
Invention of WWW in 1990.
15
LHC (Large Hadron Collider)
Circumference
26.6 km
major experiments
ATLAS
CMS
ALICE
LHCb
Approved in 1994
Completed in 2008
Cost : 10B$
16
LHC accelerator and Detectors
CMS
ALICE
tunnel
26.6 km
pp energy
7+7 TeV
luminosity
1034 cm-2s-1
dipole magnets
8.33T, 1232
LHCb
ATLAS
17
Video: Construction of LHC
(magnetToRing.wmv)
18
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
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
20
ATLAS detector under construction at November 2005
21
ATLAS : example of contribution by Japan
Endcap Muon 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 22
(2006-2008）
Construction of ATLAS
(ATLAS_construction.wmv)
23
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.
24
The beam orbit is measured
on-line by position monitors
with instant feedback actions.
Beam successfully
went 1 turn clockwise within 50 min.
of injection start.
ATLAS observed many
muons created upstream
by the proton beam.
Next day, the beam was
synchronously captured by
RF cavity resulting several
undred turns.
25
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.
A cable connection melted down
causing large He leak.
• 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.
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:
H
H
H
H
 
 Z Z         
 W W      ,   j j
 
Reconstruction of H→
2012(?)
2011(?)
• Data taking will start in Oct. 2009
(hopefully) at ECMS = 10 TeV.
2010 (?)
(red) 5s discovery line
(blue) 95% excllusion line
28
Hierarchy (fine tuning, naturalness ) problem
• 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 ~1019 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.
eR
H
H
eL
dm 
2
H
ye
16
2
2
 2
2
cutoff

 6me2 ln  cutoff / me   .....
Quantum corrections on mH
~e , ~e
R
L
H
dmH2 
H


y e~
22cutoff  4m 2e~ ln cutoff / m e~   .....
2
16
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
• Coupling constants varies as a function
of energy (distance).
 EM ( 0 )
 EM ( 0 )  q 2 
1 N
ln 2
 0 
3
 
-
+
QED : shielding (stronger as E↑）
 EM (q 2 ) 
+
2
, N  n  3  qquark
quark
Shielding by vacuum
polarization in QED
QCD : anti-shielding (weaker as E↑）
 3 (q ) 
 3 ( 02 )
2
 q2 
 3 ( 02 )
2n f  33ln 2 
1
12
 0 
due to gluon self-coupling
gluon
quark
q
clouds of gluons
& quarks
Anti-shielding by vacuum
polarization in QCD if nq < 33/2
31
GUT (Grand Unification Theory)
1 1
1 2
1 3
Three forces may be unified at 2x1016 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*cos2W
32
Dark Matter (DM)
rotation of galaxy
dark matter map
using gravity lens
motion of galactic cluster
3K microwave background
Standard Model
explains only 4%
of our Universe ! !
colliding galaxy cluster
33
Thermodynamics in expanding universe with cold DM scenario
dn
 3Hn   s A v
dt
n 2  n 2 
EQ 

 DM h 2  0.1
m ~ 0.1 ~ 1 TeV,
sv ~ 1 pb
within reach of LHC !!
Dark Matter
candidate:
Neutralinos
to be discovered
34
~
g
Detection of DM at LHC
p
• SUSY particles carry R-parity = -1:
R   13B L2 S
• Because of R-parity, LSP (lightest
supersymmetric particle) is neutral,
p
u
u
q
~
g
g
q
~0

1
(LSP)
SUSY particle production at LHC.
stable and be intact with matter, a
good DM candidate!
• LSP escapes from the detector leaving
large missing Et.
Simulated SUSY event
in CMS detector
35
Large Extra Dimension
Electro-weak scale
New approach to solve
the hierarchy problem
1016
Planck scale
3 forces
gravity in 4+2 extra
dimensions
Newton gravity
F ~ 1/r2
Interaction energy
Gravity extends to large bulk,
while SM stays on 4-dim brane.
36
LHC will reach back to 10-12 sec after the Big Bang.
37
from E. Kolb and M. Turner p.73
History of Universe
QUANTUM
GRAVITY
● Supergravity?
● Ex Dim?
● Supersymmetry?
● Superstrings?
END OF
GRAND
UNIFICATION
END OF
ELECTROWEAK
UNIFICATION
10 25 K
10 20 K
1015 K
1018 GeV 1015 GeV 1012 GeV 109 GeV 10 6 GeV
Rest Energy
of Flea
KE of
Sprinter
Highest energy
Cosmic rays
1TeV
CM Energy
of LHC
1010 K
1GeV
105 K
1MeV
1keV
Nuclear Binding
Energy
10 42 s 10 -36 s 10 -30 s 10 -24 s 10 -18 s 10 -12 s 10 -6 s 1sec
Photons

1K
1eV
1meV
Atomic
Binding Energy
1
 e      
     
Leptons  e     
&  u  c  t 
Quarks    
 d  s  b 
GLUONS
Gauge
W , Z
Bosons
X, Y, .....
of Atoms
● Formation of ● Decoupling of ● End of SUSY? Quark Hadron
Structure begins
Matter and
Transition
Big Bang
Nucleosynthesis
● Origin of MatterAntimatter Symmetry
● Monploles
● Inflation
1030 K
● Formation
MATTER
DOMINATION
103 106 109 Years
10 6 s 1012
s
 
e
n, p


H ,D ,
3
He  ,
4
He  ,
7
Li    , e 
1018 s
2K  bkgd
H , D,
3
He,
4
He,
7
Li
R(matter/radiation)=5x10-10
3K CMB
from E. Kolb and M. Turner p.73
History of Universe
QUANTUM
GRAVITY
● Supergravity?
● Ex Dim?
● Supersymmetry?
● Superstrings?
END OF
GRAND
UNIFICATION
END OF
ELECTROWEAK
UNIFICATION
10 25 K
10 20 K
1015 K
1018 GeV 1015 GeV 1012 GeV 109 GeV 10 6 GeV
Rest Energy
of Flea
KE of
Sprinter
Highest energy
Cosmic rays
1TeV
CM Energy
of LHC
1010 K
1GeV
105 K
1MeV
1keV
Nuclear Binding
Energy
10 42 s 10 -36 s 10 -30 s 10 -24 s 10 -18 s 10 -12 s 10 -6 s 1sec
 e      
     
Leptons  e     
&  u  c  t 
Quarks    
 d  s  b 
GLUONS
Gauge
W , Z
Bosons
X, Y, .....

LHC could elucidate this region
1K
1eV
1meV
Atomic
Binding Energy
1
Photons
of Atoms
● Formation of ● Decoupling of ● End of SUSY? Quark Hadron
Structure begins
Matter and
Transition
Big Bang
Nucleosynthesis
● Origin of MatterAntimatter Symmetry
● Monploles
● Inflation
1030 K
● Formation
MATTER
DOMINATION
103 106 109 Years
10 6 s 1012
s
 
e
n, p


H ,D ,
3
He  ,
4
He  ,
7
Li    , e 
1018 s
2K  bkgd
H , D,
3
He,
4
He,
7
Li
R(matter/radiation)=5x10-10
3K CMB
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 1016 GeV, 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.pdf
2) 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 B
3) ATLAS Japan group HP (日本語)
http://atlas.kek.jp
4) 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
41