Energy Frontier High Energy Physics

The LHC ProjectFebruary 18, 2009

Takahiko KondoKEK, 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

1Original file at : http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pdf

http://atlas.kek.jp/sub/OHP/2009/20090218KondoNagoya.pptx

V2 (2009.3.1)

Congratulations for the Nobel Prize in Physics 2008 !

Yoichiro Nambu Makoto Kobayashi Toshihide Maskawa1/2 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.

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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.

2V GeV 174

2V

3

1869

1995

Number of basic elements:

63 (year 1869)↓

12 (year 1995)↓

1 (year 2xxx ?) 4

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

Fundamental problems

[1] How to avoid infinity in calculations?Infinite number of higher orderterms must be summed andusually 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

7

Solution for [1] : Quantum Electro Dynamics （ QED)

Tomonaga Feynmann Schwingers

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 .

(theory) 88700011596521.0

exp.)(80850011596521.02

2

gae

"for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles”

1965

xh

(x1 y1 z1)x

hx

h

(x2 y2 z2)(x3 y3 z3)

Local gauge invariance

Theory is invariant under arbitrary rotations of internal coordinates.

)()( )( xex xiq

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 (π,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

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

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Glashow-Weinberg-Salam Theory

10[1] S. Wenberg, Phys. Rev. Lett. 19 (1967) 1264

, , ,21

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• 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

Predictions by Standard Model

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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

0gluonm

0 m

GeV 91GeV 80

Z

W

mm

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

• 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. 14

Properties of SM Higgs Particles

Higgs simulation at LHC: pp → H → Z Z → μ+μ-μ+μ- (yellow tracks).

(yellow) excluded by direct search.(blue) probability via SM radiative quantum corrections.

15

CERN 　

GenevaCERN

CERN

Founded in1954, 20 member countries, 2500 staffs, 9000 users annual budget 1,000 MCHF

Invention of WWW in 1990.

16

Circumference26.6 km

major experiments

ATLASCMS

ALICELHCb

Approved in 1994

Completed in 2008

Cost : 10B$

LHC (Large Hadron Collider)

17ATLAS

C M S

ALICE

tunnel 26.6 km 　　

pp energy 7+7 TeVluminosity 1034 cm-2s-1 dipole magnets 8.33T, 1232

LHCb

LHC accelerator and Detectors

Video: Construction of LHC 　 (magnetToRing.wmv)

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Superconducting Magnet

1232 dipole superconducting dipole magnet bends the beam.

2 beam in 1 magnetCool down to 1.9KMagnetic field 8.33

Tesla 19

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 contributionby Japan

21ATLAS detector under construction at November 2005

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

Construction of ATLAS 　 (ATLAS_construction.wmv)

23

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

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.

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• 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.

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He leak incident on 19 Sept. 2008

A cable connection melted down causing large He leak.

Some magnets moved due to He gas pressure.

28

Reconstruction of H→

Higgs discovery at LHC

2010 (?)

2011(?)

2012(?)

• 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.

(red) 5s discovery line(blue) 95% excllusion line

,

HjjWWH

ZZHH

Hierarchy (fine tuning, naturalness ) problem

• Higgs particles get large quantum mass corrections (because it is scalar)

mH = 200 GeVdmH = 1,000,000,000,000,000,000 GeVif next new physics were at ~1019 GeV (Planck scale). This is very unnatural.

Solution 1 : SUSYIf SUSY particles exist, the quadratic mass correction term exactly cancel out.

Solution 2 : Extra DimensionsThe next new physics exists at 1~10 TeV.

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...../ln6216 cutoff

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Quantum corrections by SUSY particles

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.

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

• 　

quark

quark

EM

EMEM qn

qN

q 2

2

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ln3

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Shielding by vacuum polarization in QED

Running coupling constants

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qn

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Anti-shielding by vacuum polarization in QCD if nq < 33/2

clouds of gluons & quarks

quark

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32

GUT (Grand Unification Theory)

11

21

31

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*cos2W

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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 ! !

SUS

Y (M

SSM

)

34

to be discovered

Dark Matter

candidate:Neutralino

s

within reach of LHC !!

Thermodynamics in expanding universe with cold DM scenario

Sta

ndar

d M

odel

223 EQnnvAHn

dtdn s

1.02 hDM

pb 1 ~ v TeV, 1~1.0~ sm

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 Et.

SLBR 231 0

1~ (LSP)

g~

g~

u

uq

qg

p

p

SUSY particle production at LHC.

dete

ctor

Detection of DM at LHC

Simulated SUSY event in CMS detector

Large Extra Dimension New approach to solve the hierarchy problem

Interaction energy

3 forces

gravity in 4+2 extra dimensions

Electro-weak scale Planck scale1016

Newton gravity F ~ 1/r2

Gravity extends to large bulk, while SM stays on 4-dim brane.

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

37

1K K 10K 10K 10K 10K 10K 10 51015202530

10 10 10 1 10 10 10 10 10 10 10 ssssecsssssss 18 1266-12-18-24-30-36-42

meVeVkeVMeVGeVTeV 1 1 1 1 1 1 10 10 10 10 10 GeV6 GeV9 GeV12GeV15GeV18

Rest Energy KE of Highest energy CM Energy Nuclear Binding Atomic of Flea Sprinter Cosmic rays of LHC Energy Binding Energy

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? ● Monploles Nucleosynthesis

● Inflation

History of Universefrom E. Kolb and M. Turner p.73

B I

G

B

A

N

G

Leptons &

Quarks

GaugeBosons

Photons

..... Y,X, Z,W

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3K CMB

2K bkgd

1 103 106 109 Years

1K K 10K 10K 10K 10K 10K 10 51015202530

10 10 10 1 10 10 10 10 10 10 10 ssssecsssssss 18 1266-12-18-24-30-36-42

meVeVkeVMeVGeVTeV 1 1 1 1 1 1 10 10 10 10 10 GeV6 GeV9 GeV12GeV15GeV18

Rest Energy KE of Highest energy CM Energy Nuclear Binding Atomic of Flea Sprinter Cosmic rays of LHC Energy Binding Energy

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? ● Monploles Nucleosynthesis

● Inflation

History of Universefrom E. Kolb and M. Turner p.73

B I

G

B

A

N

G

Leptons &

Quarks

GaugeBosons

Photons

..... Y,X, Z,W

GLUONS

bt

sc

duee

pn

e

,

eLiHeHeDH

,,,,,

7

4

3

LiHeHeDH

7

4

3

,,,,

R(matter/radiation)=5x10-10

3K CMB

2K bkgd

1 103 106 109 Years

LHC could elucidate this region

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 1016 GeV, corresponding to 10-11 to 10- 38sec after the Big Bang.

Summary

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

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