Transcript SubAtomic Physics & Astrophysics Intimate Connexion

SubAtomic Physics
&
Astrophysics
Intimate Connexion
between Very Large
and Very Small
Plan of Talk
•
Research Interests at Toronto
•
Standard Model of Particle Physics
•
Puzzles
•
Profound connexion between
understanding of microstructure and
macrostructure of universe.
•
Solutions????
•
Experiments
Interest Groups @ UofT
•
Experimental Particle Physics
Origin of Mass, Structure of Proton ….
Large Projects: ATLAS, CDF, ZEUS
Bailey, Martin, Orr, Sinervo, Trischuk
6 Post Docs
12 grad students
•
Experimental Cosmology
Geometry of Space-Time
Large Project: Boomerang
Netterfield - just starting !
1 grad student
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Theoretical Particle Physics
Origin of Mass,
Structure of Hadronic Matter
Holdom, Luke, O’Donnell
3 Post Docs
4 grad students
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Large Program In Astrophysics
Galaxy Formation
Large Scale Structure of Universe
Cosmic Background Radiation
Stellar Dynamics ...
Bond, Martin, Kofman, Murray, Pen
25 visitor & fellows
9 grad students
Is the Universe Made of These?
Quantum Forces
•
In Quantum Field Theory, particles interact
via:.
Exchange of virtual particles
Electrons interact by exchanging:
Virtual Photons
Quarks interact by exchanging:
Virtual Gluons
Weak Interaction
•
A force very like electromagnetism; but
acts on Weak Charge
W  Z 0
• In Fact, electromagnetism and weak force
are aspects of unified electroweak force
• Electric charge and weak charge are
related
• Three “force carriers”
 0
W Z
Higgs Boson
• Electromagnetism on its own can be made
to give finite results for all calculations.
• Unified Electroweak theory gives infinite
results for process like:
• Become finite if include new particle
Higgs boson

0
Z massive, and
• Higgs makes W
actually generates masses of all particles. It
is a quantum field permeating the universe.
How Does Higgs Generate Mass?
• In vacuum, a photon:
has velocity c and has zero mass
• In glass a photon
has velocity < c , same as an effective mass
• This is due to photon interacting with
electromagnetic field in condensed matter
• By analogy can understand masses of particles
generated by Higgs Field in vacuum
Grand Unification.
•
At a high enough energy
electromagnetism
weak force
strong (colour) force
become aspects of Grand Unified Force
The Universe is Expanding
Its ultimate fate depends on density of matter
and energy
• If 0 , the density of matter and energy is
greater that a critical density c the universe
will start to contract
• If 0 is less than the critical density, the
universe will continue to expand.
• Usually measure the density in units of
0 8G 0
0 

c
3 H02
•  0 1 spherical space-time: contraction
•
 0 1 flat space-time: expansion
•  0 1 hyperbolic space-time: expansion
Experimental Mystery
B
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Density of Standard Model Matter
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If Universe is made of quarks & leptons
 B  0 1
 B 0.05
•
Find
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Density of all gravitationally interacting
matter
 M 0.4 0.1
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Most of Universe is not Standard Model
matter. Some kind of Dark Matter
Measuring  0
•
Amazingly enough can measure
total matter/energy density in universe
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Measure temperature fluctuations in
remnant of fireball from Big Bang.
 0 1
Map of sky temp
~ 3 Kelvin
Boomerang: Measuring Fluctuations in
Cosmic Microwave
Background Radiation.
Gondola with temperature
measuring “telescope”
Flight path over Antarctica
Readying for launch
Mount Terror forms
a backdrop.
Need for Supersymmetry
•
In Grand Unified Theories cannot Unify
forces, unless postulate unseen form of
matter
• Higgs mass runs away to Plank Scale
• Three forces never have same strength
• Unless all particles have supersymmetric
sparticle partners (of higher mass)
+
Sleptons
Squarks
Spin 1
Bosinos
Spin1/2
SUSY + Dark Matter
•
Supersymmetric Particles are unstable
Susy  Normal Susy
•
Eventually decay chain ends in Normal
matter + lightest SUSY particle
• Lightest SUSYparticle cannot interact with
normal matter
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Lightest SUSY particle good candidate for
Dark Matter
•
Hope to produce
(SUSY - antiSUSY ) pairs and Higgs
at
Large Hadron Collider
How to Make Matter / AntiMatter?
Colliding high energy beams
Energy of beams transformed into mass
of new particles
LHC will be proton - proton collider
Fermilab is proton - antiproton
HERA is electron - proton
Typical Accelerator Complex
CERN Seen from the Air
• Tunnels of CERN accelerator complex
superimposed on a map of Geneva.
• Accelerator is 4.3km in radius 50 m
underground
LHC Tunnel
This is an arc of the circular tunnel
Circumference 26.7 Km
Collider Detector @ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the
six quark
Top - completes
quark
generations
Collider Detector @ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the
six quark
Top - completes
quark
generations
Collider Detector @ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the
six quark
Top - completes
quark
generations
ZEUS ep Collisions - Proton Structure
ep Collision
seen in ZEUS
Experimental confirmation
of equal strength of weak
and electromagnetic forces
at high energy
Electroweak Unification
ATLAS @ CERN LHC
Computer Simulation
of discovery of
Higgs Boson