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Linear ColliderHitoshi Murayama (Berkeley)EPP2010@SLAC, Jan 31, 2005
2
Take-home messages
•We are approaching a new layer of energy scale: something is brewing at TeV-scale
•Solutions to many deep puzzles hinge on what we find at this energy scale
•multiple tools needed to get a complete picture
3
Outline
•Brief Recap of Science
•Need for Multiple Tools
•Dark Field=Cosmic Superconductor
•Linear Collider
Brief Recap of Science
5
Energy budget of Universe
•Stars and galaxies are only ~0.5%
•Neutrinos are ~0.1–1.5%
•Rest of ordinary matter
•(electrons, protons & neutrons) are 4.4%
•Dark Matter 23%
•Dark Energy 73%
•Anti-Matter 0%
•Dark Field (Higgs) ~1062%??
6
Einstein’s Dream•Is there an underlying
simplicity behind vast phenomena in Nature?
•Einstein dreamed to come up with a unified description
•But he failed to unify electromagnetism and gravity (GR)
7
History of Unification
gravity
electric magnetic
α-decay
-decay
-decay
planets apple electromagnet
ism
atoms
Quantum mechanics
mechanics
Special relativityQuantum ElectroDynamics
Weak force
Strong Force
Electroweak theory
GR
String theory? Grand Unification?
8
deeper into the heart of the
matter (literally)
My son on Halloween!Einstein?
increase resolution
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resolution=energy
•Quantum Mechanics: particle=wave
•higher energy
•= shorter wavelength
•= better resolution
low energy
high energy
10
a new layer of unification
•Unification of electromagnetic and weak forces
⇒electroweak theory
•Long-term goal since ‘60s
•We are finally getting there!
•If they are unified, what makes them so different?
⇒Dark Field!
HERA ep collider
EM
weak
electromagnet
ism
weak
inflation
unificationstringanti-matter
Need for Multiple Tools
13
Multiple Wavebands
in Astronomy
14
Evidence forDark Matter
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Galaxies are held together by mass far bigger than all stars combined
Radiovisible
15
•Yet another tool: cosmic microwave background
•matter/all atoms=6.03±0.03
•Dominant paradigm:
•Stable heavy particle produced in early Universe (E=mc2!)
•left-over from near-complete annihilation
•TeV: the correct temperature to produce them
Dark Matter is not atoms
16
Telescopes vs Accelerators
aim need telescopes acceleratorsprobe deeper
better resolution
better mirrors, CCD
higher energy
better imagebetter
exposure
larger telescopes, more time
more powerful beams
(luminosity)
full understandi
ng
multiple probes
visible, radio, X-ray,
infrared, UV, gamma
protons, electrons, neutrinos
17
QuickTime™ and aGIF decompressor
are needed to see this picture.
Strong Force•Back to 1930s•atomic nuclei made of
protons and neutrons•why don’t protons
repel each other and nuclei disintegrate?
•a new mysterious “strong force” binding them together
•range of the force 0.000001 nanometer
•need 100 MeV to study
Yukawa predicted the force carrier whose mass is 100 MeV in 1933
discovered in 1947 (140 MeV)case closed?
18
Strong Force•It was rather just
the beginning
•Soon proliferation of strongly-interacting particles at proton-based machines
•a big mess! (i.e. fun)
19
Obstruction to Cosmology
•S. Weinberg “Gravitation and Cosmology” (1972)
•15.11 The Very Early Universe• If we look back into the first 0.0001 sec of cosmic history,
we encounter theoretical problems. At such temperatures copious number of strongly interacting particles will be in a state of continual mutual interaction and cannot reasonably be expected to obey any simple equation of state.
•There are two extremely different simple models that reflect two divergent views of the nature of the strongly interacting particles. Neither model can be taken seriously.
20
Electron scattering•electron proton
scattering experiment
•looked dumb because electrons don’t do the strong force
•clear roles:
•electron=probe
•proton=object
•found that protons have constituents: “quarks”
•1990 Nobel:
•Friedman, Kendall, Taylor
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electron positron collider
can see quarks and a gluon ~19802004 Nobel to Gross, Wilczek, Politzer
Dark Field =cosmic
superconductor
23
Mystery ofthe “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 0.000000001 nanometer
•[need it for the Sun to burn!]
•We know the energy scale: 0.3 TeV
24
We are swimming in Dark Field
•There is something filling our Universe
•It doesn’t disturb gravity or electric force
•It does disturb weak force and make it short-ranged
•It slows down all elementary particles from speed of light
•What is it??•Extremely bizarre
theory!
25
Cosmic 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 superconductor
•She finally figured:
•magnetic field must be long-ranged
• there must be a mysterious charge-two “Dark Field” in her “Universe”
•But doesn’t know what the Dark Field is, nor why it is there
•Doesn’t have enough energy (gap) to break up Cooper pairs
• That’s the stage where we are!
QuickTime™ and aIndependent JPEG Group decompressor
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26
Kick out Dark Field from the vacuum
•We know the energy scale of the problem:
•0.3 TeV
•pump energy into empty space to kick out whatever makes Dark Field: “Higgs boson”
•LHC will find it!!!!!
27
Better be sure•For something this bizarre, we’d better
make sure
•Is the particle discovered really the Higgs boson?
•Is it really responsible for particle masses?
•Does this have the right properties?
•Is it really stuck in our Universe?
•Need detailed measurements for the proof
28
Post-Higgs Problem
•We see “what” is stuck in our universe
•But we still don’t know “why”
•Two problems:
Why anything is stuck at all
Why is the scale of Dark Field 0.3TeV much much smaller than the scale of gravity ~1015 TeV
•Explanation most likely to be at ≤TeV scale because this is the relevant energy scale
29
Three Directions•History repeats itself•discovery of anti-matter doubled #particles•Double #particles again ⇒ supersymmetry
•Learn from Cooper pairs again•Cooper pairs composite made of two electrons•Higgs boson may be pairwise composite • ⇒ technicolor
•Physics as we know it ends at TeV•Ultimate scale of physics: quantum gravity•May have quantum gravity at TeV • ⇒ hidden dimensions (0.01 cm to 10–17 cm)
30
•Higgs boson as a Pseudo-Nambu-Goldstone boson (Little Higgs)
•Higgs boson as an extra-dimensional gauge boson (Gauge-Higgs Unification)
•Fat Higgs (Composite)
•Higgsless and W± as Kaluza-Klein boson
•technicolorful supersymmetry
More Directions
31
32
Task•Why is there Dark Field?
•We can eliminate many possibilities at LHC
•But new interpretations necessarily emerge
•Race will be on:
•theorists coming up with new interpretations
•experimentalists excluding new interpretations
⇒A loooong process of elimination
•Crucial information is in details
⇒Reconstruct the theory from measurements
33
Need absolute confidence for a major
discovery
•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.”
As an example, supersymmetry
“New-York Times level” confidence
inflation
unificationstringanti-matter
InternationalLinear Collider
(ILC)
36
ILC
•electron position collider at 0.5-1 TeV
•about 20 miles long•super-high-tech: nanometer beams
37
ILC
•elementary particles
•well-defined energy, angular momentum
•uses its full energy
•can produce particles democratically
•can capture nearly full information
LHC
ILC
pp
e+ e-
38
ILC•superconducting
cavities for main accelerator
•technology is extremely challenging, yet basically at hand
•world-wide design in development
•need to complete the design (a real work!)
39
LHC vs ILC(oversimplified)
total energy 14TeV 0.5-1 TeV
usable energy a fraction full
beamproton
(composite)electron (point-
like)
signal rate high low
noise rate very high low
analysis specific modes nearly all modes
eventslose info along
the beamscapture the
whole
statusunder
constructionneeds to finish
design
40
Take-home messages
•We are approaching a new layer of energy scale: something is brewing at TeV-scale
•Solutions to many deep puzzles hinge on what we find at this energy scale
•multiple tools needed to get a complete picture
41
In the Next Talk:•See how ILC, together with LHC
•can establish Higgs generates all masses
•can establish supersymmetry
•can test unification
•can figure out what Dark Matter is
•can study extra dimensions, measure their number, shape, geometry