present and future of high energy physics - cern · present and future of high energy physics...

Present and Future of High Energy Physics

Hitoshi Murayama (IPMU Tokyo, Berkeley)EPAC 2008, Genoa, Italy

June 27, 2008

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Accelerators and Particle Physics

accelerators have been the enabling technology for particle physicsnon-accelerator experiments are becoming more important partly because of price tagsHowever, I expect & hope that accelerator-based HEP remains main drivers in the foreseeable future

2

non-accelerator physics

3


Many non-accelerator physics discoveries had to be confirmed, studied, and improved using accelerators

3


Many non-accelerator physics discoveries had to be confirmed, studied, and improved using acceleratorsbatteries: electrons as cathode ray

3


Many non-accelerator physics discoveries had to be confirmed, studied, and improved using acceleratorsbatteries: electrons as cathode raycosmic-ray: muons, pions, kaons

3


Many non-accelerator physics discoveries had to be confirmed, studied, and improved using acceleratorsbatteries: electrons as cathode raycosmic-ray: muons, pions, kaonsatmospheric neutrinos: oscillations

3


Many non-accelerator physics discoveries had to be confirmed, studied, and improved using acceleratorsbatteries: electrons as cathode raycosmic-ray: muons, pions, kaonsatmospheric neutrinos: oscillationsdark matter: LHC & ILC?

3

Major Achievements >2000

4


amazing precision measurements from PEP-II/KEK-B establishing KM theory

4



large data set from Tevatron discovering Bs mixing, precision studies of W, top, narrowing range for the SM Higgs

4



large data set from Tevatron discovering Bs mixing, precision studies of W, top, narrowing range for the SM Higgs

K2K/MINOS confirmation of neutrino oscillation

4

Outline

IntroductionEnergy Frontier

Firm and established needs for TeVless firm but exciting needs for beyond

Intensity Frontierneeds for intense neutrinoshigh precision flavor physics

5

Energy Frontier

New Era

7

New Era

∼1900 reached atomic scale 10-8cm≈α/me

7

New Era


∼1970 reached strong scale 10-13cm≈Me-2π/αs b0

7

New Era



∼2010 will reach weak scale 10-17cm

7

New Era



∼2010 will reach weak scale 10-17cmknown since Fermi (1933), finally there!

7

New Era



∼2010 will reach weak scale 10-17cmknown since Fermi (1933), finally there!presumably it is also a derived scale more fundamental theory

7

New Era



∼2010 will reach weak scale 10-17cmknown since Fermi (1933), finally there!presumably it is also a derived scale more fundamental theorysupersymmetry? extra dimensions? string theory?

7

New Era



∼2010 will reach weak scale 10-17cmknown since Fermi (1933), finally there!presumably it is also a derived scale more fundamental theorysupersymmetry? extra dimensions? string theory?If so, we expect rich spectrum of new particles!

7

9

Mystery of the “weak force”

Gravity pulls two massive bodies (long-ranged)Electric force repels two like charges (long-ranged)“Weak force” pulls protons and electrons (short-ranged) acts only over 10–16 cm [need it for the Sun to burn!]

10

Something is in the Universe

There is something filling our UniverseIt doesn’t disturb gravity or electric forceIt does disturb weak force and make it short-rangedIn fact, it is the “mother of mass” for all elementary particlesWhat is it??

gravity

electric force

weak force

11

Like a superconductor

In a superconductor, magnetic field gets repelled (Meißner effect), and penetrates only over the “penetration length” ⇒ Magnetic field is short-ranged!

Imagine a physicist living in a superconductorShe finally figured:

magnetic field must be long-ranged there must be a mysterious charge-two condensate in her “Universe”But doesn’t know what the condensate is, nor why it condensesDoesn’t have enough energy (gap) to break up Cooper pairs

That’s the stage where we are!

12

Large Hadron Collider (LHC):Exploring the TeV-scale

1

10

100

100 120 140 160 180 200

Sig

nal

sig

nif

ican

ce

Total significance

!Ldt = 30 fb"1

(no K-factors)

ATLAS

5#

mH (GeV/c2)

H $ %%

ttH (H $ bb)H $ ZZ(*) $ 4l

H $ WW(*) $ l&l&qqH $ qqWW(*)

qqH $ qq''

Robust discovery

13

Questions to be answered

13


Is the particle discovered really the Higgs boson?Is it really responsible for particle masses?Does this have the right quantum number JP=0+?Is it condensed in the Universe?

13


Is the particle discovered really the Higgs boson?Is it really responsible for particle masses?Does this have the right quantum number JP=0+?Is it condensed in the Universe?

Prove it is the “Mother of Mass”Spin/Parity CouplingsBranching RatiosSize of the condensate

14

Linear Collider

International Linear Collider (ILC)

ElectronsPositrons

Drawing not to scale

February 2007

14

Linear Collider

International Linear Collider (ILC)

ElectronsPositrons

Drawing not to scale

February 2007 ! !-

-+

+

(GeV)

10

10

1

-3

-2

10-1

SM

Hig

gs

Bra

nch

ing

Ra

tio

bb

ggcc

""

MH

W W

100 110 120 130 140 150 160

Branching Fractions test the relation: coupling ∝ mass

⇒ proves that Higgs Boson is the Mother of Mass

TeV to multi-TeV

Three reasons beyond Higgs

Hierarchy Problem

Dark Matter of the Universe

Physics behind Higgs

all suggest rich physics at

sub-TeV to multi-TeV

16

17

Evidence for Dark Matter

17

Evidence for Dark Matter

Galaxy is held together by mass far bigger than all stars

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WMAP satellite result ΩMh2=0.135±0.009Ωbh

2=0.0224±0.0009ΩM/Ωb=5.70+0.39-0.61dark matter is not atoms!

Cosmic Microwave Background

It must be WIMP (Weakly Interacting Massive Particle)

Stable heavy particle produced in early Universe, left-over from near-complete annihilation

WIMP

It must be WIMP (Weakly Interacting Massive Particle)

Stable heavy particle produced in early Universe, left-over from near-complete annihilation

WIMP

ΩM =0.756(n +1)x f

n+1

g1/2σannMPl3

3s08πH0

2 ≈α 2 /(TeV)2

σann

20

Post-Higgs Problem

We see “what” is condensedBut we still don’t know “why”From Ginzburg-Landau to BCS theoryTwo problems:

Why anything is condensed at allWhy is the scale of condensation ~TeV<<MPl=1015TeV

Explanation most likely to be at ~TeV scale because this is the relevant energy scalestudy Higgs properties and interaction in detail!

Once upon a time,there was a hierarchy problem...At the end of 19th century: a “crisis” about electron

Like charges repel: hard to keep electric charge in a small packElectron is point-likeAt least smaller than 10–17cm

Need a lot of energy to keep it small!

Correction Δmec2 > mec

2 for re < 10–13cmBreakdown of theory of electromagnetism ⇒ Can’t discuss physics below 10–13cm

Δmec2 ~ α

re~ GeV10

−17cmre

21

Anti-Matter Comes to Rescueby Doubling of #Particles

Electron creates a force to repel itselfVacuum bubble of matter anti-matter creation/annihilationElectron annihilates the positron in the bubble⇒ only 10% of mass even

for Planck-size

e–

!

e–

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for Planck-size

e–

e+

!

e–

!

e–

22



for Planck-size

e–

e+

!

e–

!

e–

e–

e+

!

e–

22



for Planck-size

e–

e+

!

e–

!

e–

e–

e+

!

e–

!me

me

!

!

4"

log(mere)

22

Higgs repels itself, too

Just like electron repelling itself because of its charge, Higgs boson also repels itselfRequires a lot of energy to contain itself in its point-like size!Breakdown of theory of weak forceCan’t even think about short distance physics!

€

ΔmH2 c4 ~ c

rH

2

shorter

distance

EW scale

SM breaks

down here

physics that

answers

questions

~100GeV

~1TeV

???

H H

H

23

History repeats itself?

Double #particles again ⇒ superpartners

“Vacuum bubbles” of superpartners cancel the energy required to contain Higgs boson in itselfStandard Model made consistent with whatever physics at shorter distances

24shorter

distance

EW scale

SM breaks

down here

physics that

answers

questions

~100GeV

~1TeV

???




€

ΔmH2 ~ α

4πmSUSY2 log(mHrH )

H H

H

H H

H~

W~

24shorter

distance

EW scale

SM breaks

down here

physics that

answers

questions

~100GeV

~1TeV

???




€

ΔmH2 ~ α

4πmSUSY2 log(mHrH )

H H

H

H H

H~

W~

24shorter

distance

EW scale

SM breaks

down here

physics that

answers

questions

~100GeV

~1TeV

???

shorter

distance

EW scale

SUSY

physics that

answers

questions

~100GeV

~1TeV

???

25

Three Directions

25

Three Directions

History repeats itselfCrisis with electron solved by anti-matterDouble #particles again ⇒ supersymmetry

25

Three Directions


Learn from Cooper pairsCooper pairs composite made of two electronsHiggs boson may be fermion-pair composite ⇒ technicolor

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Three Directions


Learn from Cooper pairsCooper pairs composite made of two electronsHiggs boson may be fermion-pair composite ⇒ technicolor

Physics as we know it ends at TeVUltimate scale of physics: quantum gravityMay have quantum gravity at TeV ⇒ hidden dimensions (0.01 cm to 10–17 cm)

Need absolute confidence for a major discovery


As an example, supersymmetry


As an example, supersymmetry“New-York Times level” confidence



The Other Half of the World Discovered

July 23, 2009

Geneva, Switzerland


still a long way to



July 23, 2009

Geneva, Switzerland


still a long way to

“Halliday-Resnick” level confidence



July 23, 2009

Geneva, Switzerland


still a long way to

“Halliday-Resnick” level confidence

“We have learned that all particles we observe have unique partners of different spin and statistics, called superpartners, that make our theory of elementary particles valid to small distances.”



July 23, 2009

Geneva, Switzerland

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Hidden Dimensions

Hidden dimensions

Can emit graviton into the bulk

Events with apparent energy imbalance

⇒ How many extra dimensions are there?

G

e

e

!

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Hidden Dimensions

Hidden dimensions

Can emit graviton into the bulk

Events with apparent energy imbalance

⇒ How many extra dimensions are there?

G

e

e

!

LC

5

10

20

30

50

100

200

400 450 500 550 600 650 700 750 800 850 900

ECM (GeV)

!G / (

fb)

D=6

D=7

D=8

D=9

D=10ILC

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Supersymmetry

Tevatron/LHC will discover supersymmetry

Can do many measurements at LHC

! L dt = 1, 10, 100, 300 fb-1

A0= 0, tan! = 35, µ > 0

ET

(300 fb-1)miss

ET

(100 fb-1)miss

ET

(10 fb-1)miss

ET

(1 fb-1)miss

g(1000)~

q(1500)

~

g(1500)~

g(2000)~

q(2500)

~

g(2500)~

q(2000)

~

g(3000)~

q(1000)

~

q(500)

~g(500)~

!h2 =

0.4

!h2 =

1

!h 2 =

0.15

h(110)

h(123)

1400

1200

1000

800

600

400

200

50000

1000 1500 2000

m0 (GeV)

m1

/2(G

eV

)

EX

TH

CMS

one year

@1033

one year

@1034

one month

@1033

Fermilab reach: < 500 GeV

one week

@1033cosmologically plausible

region

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300 350 400

S5

O1

M! (GeV)"1

0

Ml (

Ge

V)

" R

LHC LHC

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Prove Superpartnershave different spin

Discovery at Tevatron Run II and/or LHCTest they are really superpartners

Spins differ by 1/2Same SU(3)×SU(2)×U(1) quantum numbersSupersymmetric couplings

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Spin 0?

30




Spin 0?

#E

vents

cos !

150

100

50

0–1 –0.5 0 0.5 1

e+e" # µ+µ"

$s = 350 GeV

% %

Tsukamoto, Fujii, HM, Yamaguchi, Okada

ILC

31

Creating Dark Matter

Look for reactions where energy and momenta are unbalanced

“missing energy” Emiss

Something is escaping the detectorelectrically neutral, weakly interacting⇒Dark Matter!?

4.8Gev EC19.Gev HC

YX hist.of BA.+E.C.0| ! 500cm 500cm|X

0|!500cm

500cm|

Y

Dark Matter Concordance

abundance

32

Dark Matter Concordance

abundance direct detection

32

Required New Facilities

LHC & ILC may do it if new particles are light enoughPossibly, we need to go beyond themneed a tandem of proton & leptonneed to keep eyes on a few to 10 TeVhigher gradient cavities, CLIC, high-field magnets, muon collider, plasma

33

Intensity Frontier

35

Baryon AsymmetryEarly Universe

10,000,000,001 10,000,000,000

q q_

36

Baryon AsymmetryCurrent Universe

1us

The Great Annihilationq q

_

37

CP Violation

Is anti-matter the exact mirror of matter?1964 discovery of CP violation in neutral kaon systemBut only one system, hard to tell what is going on.2001 Found kaon and anti-kaon decay differently at 10–6 level2002 Found CP violation also in B-meson systemBut no CP violation observed so far is large enough to explain the absence of anti-matter

Entr

ies

/ 0.6

ps

B0 tags

B! 0

tags

Background

"t (ps)

Raw

Asy

mm

etry

0

50

100

150

-0.5

0

0.5

-5 0 5

BaBar

38

Leptogenesis

Neutrinos may be their own anti-particles

They can transform matter to anti-matter and vice versa

Maybe they are responsible for our existence!

38

Leptogenesis

Neutrinos may be their own anti-particles

They can transform matter to anti-matter and vice versa

Maybe they are responsible for our existence!

• CP-violation may be observed in neutrino oscillation

• Plans to shoot neutrino beams over thousands of kilometers to see this

P (!µ ! !e)" P (!̄µ ! !̄e) = "16s12c12s13c213s23c23

sin " sin

!!m2

12

4EL

"

sin

!!m2

13

4EL

"

sin

!!m2

23

4EL

"

First Steps

39

Neutrino beam

Far detector

NOνAMINOS

First Steps

39

Neutrino beam

Far detector

NOνAMINOS

T2K startsnext year

40

Very Long Baseline Experiment

40

Very Long Baseline Experiment

Shoot the beams over thousands of kilometers to see

CP violation in neutrinos

Once new particles at TeV

41

What do they do with flavor?Do they come in three generations?If so, do they mix the same way as quarks and leptons?If not, do their interactions preserve or violate flavor?

Ultimately, what is the origin of flavor?need a large sample of kaons, muons, B’s


high-intensity proton machine (4MW?)to produce intense neutrino beamsto create kaons for precision studies

high-intensity electron machine (1036?)to create B mesons for precision studies

high-intensity muon source (1020?)neutrino factorymuon flavor physics

42


high-intensity proton machine (4MW?)to produce intense neutrino beamsto create kaons for precision studies

high-intensity electron machine (1036?)to create B mesons for precision studies

high-intensity muon source (1020?)neutrino factorymuon flavor physics

42much stronger case with LHC discoveries

Conclusions

43

Conclusions

Accelerators will remain critical drivers for particle physics research

43

Conclusions

Accelerators will remain critical drivers for particle physics researchFirm case for LHC & ILC followup

43

Conclusions

Accelerators will remain critical drivers for particle physics researchFirm case for LHC & ILC followupGood reasons to except more excitement, likely to need to go multi TeV scales

dark matter, beyond Higgs, hierarchy

43

Conclusions


dark matter, beyond Higgs, hierarchyNeed high intensity neutrinos

43

Conclusions


dark matter, beyond Higgs, hierarchyNeed high intensity neutrinosneed to study consequences of new particles on flavor physics

43

Our Future Rests On You!

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