SubAtomic Physics

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SubAtomic Physics Astrophysics

Intimate Connexion between Very Large
and Very Small
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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

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Interest Groups _at_ 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
• Theoretical Particle Physics
• Origin of Mass,
• Structure of Hadronic Matter
• Holdom, Luke, ODonnell
• 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

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Is the Universe Made of These?
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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
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Weak Interaction

• A force very like electromagnetism but
• acts on Weak Charge

• In Fact, electromagnetism and weak force
• are aspects of unified electroweak force
• Electric charge and weak charge are
• related
• Three force carriers

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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
• Higgs makes massive, and actually
  generates masses of all particles. It is a
  quantum field permeating the universe.

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How Does Higgs Generate Mass?

• In vacuum, a photon
• has velocity c and has zero mass
• In glass a photon
• has velocity lt 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

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Grand Unification.

• At a high enough energy
• electromagnetism
• weak force
• strong (colour) force
• become aspects of Grand Unified Force

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• The Universe is Expanding
• Its ultimate fate depends on density of matter
  and energy
• If , the density of matter and energy is
  greater that a critical density the
  universe will start to contract
• If is less than the critical density,
  the universe will continue to expand.
• Usually measure the density in units of
• spherical space-time
  contraction
• flat space-time expansion
• hyperbolic space-time expansion

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Experimental Mystery

• Density of Standard Model Matter
• If Universe is made of quarks leptons
• Find
• Density of all gravitationally interacting matter
  
• Most of Universe is not Standard Model matter.
  Some kind of Dark Matter

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Measuring

• Amazingly enough can measure
• total matter/energy density in universe
• Measure temperature fluctuations in remnant of
  fireball from Big Bang.

Map of sky temp 3 Kelvin
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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.
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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 Bosinos Squarks Spin 1
Spin1/2
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SUSY Dark Matter

• Supersymmetric Particles are unstable
• Eventually decay chain ends in Normal matter
  lightest SUSY particle
• Lightest SUSYparticle cannot interact with
• normal matter
• Lightest SUSY particle good candidate for
• Dark Matter
• Hope to produce
• (SUSY - antiSUSY ) pairs and Higgs
• at

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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
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Typical Accelerator Complex
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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

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LHC Tunnel
This is an arc of the circular tunnel Circumferenc
e 26.7 Km
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Collider Detector _at_ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the six quark Top - completes
quark generations
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Collider Detector _at_ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the six quark Top - completes
quark generations
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Collider Detector _at_ Fermilab
UofT involved in upgrading silicon vertex detector
Discovered the six quark Top - completes
quark generations
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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
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ATLAS _at_ CERN LHC
Computer Simulation of discovery of Higgs Boson
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