particle physics: the search for the essence of matter
TRANSCRIPT
Particle Physics: The Search for the Essence of Matter
Ronan McNulty (University College Dublin)
Particle Physics has been around for a long time…
It is in our natureas humans to be
inquisitive and to ask“Why?”
• Thales: “Of what is the universe made?”
• Anaximander: “Worlds appear and disappear as a bubble in the apeiron”
• Democritus:
Atom = ‘indivisible’
• Morning Ireland:
“What is the stuff in stuff?”
• Particle Physics
– searches for the building blocks of matter
– explains how they behave
Mendeleev 1869"fearful symmetry independent of any
conception as to the nature of the elements
The Periodic Table
The New Periodic Table
Exploring the very small requires high energy
E=hυ=hc/λ λ=(1x10-6)/E metres
Exploring the very small requires high energy
E=hυ=hc/λ λ=(1x10-6)/E metres
To see down to 10-19m requires 10 TeV of energy
Cockroft & Walton 1932
Linear Accelerator
Circular Accelerator
A low energy particle accelerator...
The LHC
The LHC
Tracking chambers measure Momentum of charged particles
Calorimeters measure energy of neutral particles
LHC recreates conditions of early universe
• Investigate matter-
antimatter assymetry
of universe
• Understand the origin
of mass
• Might find dark matter
Particle Physics|
Astrophysics
Where is all the Antimatter gone?
Matter and Antimatter
created equal and opposite
Today only Matter remains
Where is all the Antimatter gone?
Matter and Antimatter
created equal and opposite
Today only Matter remains
Sakharov Conditions
�Baryon Number Violation
�CP Asymmetry
�Universe not in Thermal
Equilibrium during expansion
Our Matter World
Our Matter World
An Antimatter World
C
Our Matter World Our World reflected in a mirror
P
C
P
CP
C
P
CP
Inexact CP symmetry
explains inexact
matter/antimatter symmetry
LHCb experiment
Matter
Antimatter
Do the
decays
mirror
each
other?
C P
UCD helped build and test the VELO: Reconstruct particle trajectories to 1/100 mm
LHCb see the first LHC collisions!
So have we reached the end?Do we “know everything” ?
• We have our ‘periodic table’ of fundamental particles.
• It is complete.
• We understand how the particles interact via four forces.
• Why are particles massive?
• Why is the universe dominated by matter and not anti-matter?
• What is the ‘dark matter’ in the universe?
• Are quarks/leptons fundamental?
• Why are there exactly three families?
The more we knowthe more we knowwe do not know.