Transcript The Big Bang, the LHC and the Higgs Boson Dr Cormac O’ Raifeartaigh (WIT)

The Big Bang, the LHC and the Higgs Boson
Dr Cormac O’ Raifeartaigh (WIT)
Overview
I. LHC
What, How and Why
II. Particle physics
The Standard Model
III. LHC Expectations
The Higgs boson and beyond
Big Bang Cosmology
The Large Hadron Collider
High-energy proton beams
Opposite directions
Huge energy of collision
E = mc2
Create short-lived particles
Detection and measurement
No black holes
Why
Explore fundamental constituents of
matter
Investigate inter-relation of forces
that hold matter together
Study early universe
Highest energy since BB
Mystery of dark matter
Mystery of antimatter
Cosmology
E = kT → T =
How
E = 14 TeV
λ =1 x 10-19 m
Ultra high vacuum
Low temp: 1.6 K
LEP tunnel: 27 km
Superconducting magnets
Particle detectors
Careers
Mathematics
Theoretical physics
theory
expected collisions
Experimental physicists
Engineers
experiments
detector design
Computer scientists
Software engineers
world wide web
GRID
Particle physics (1930s)
• atomic nucleus (1911)
• most of atom empty
• electrons outside
• inside the nucleus
proton (1909)
neutron (1932)
• strong nuclear force?
Periodic Table:
determined by protons
Four forces of nature
Force of gravity
Holds cosmos together
Long range
Electromagnetic force
Holds atoms together
Strong nuclear force
Holds nucleus together
The atom
Weak nuclear force:
Radioactivity
Splitting the nucleus (1932)
Cockcroft and Walton: linear accelerator
Accelerator used to split the nucleus
H1 + Li3 = He2 + He2
Verified mass-energy (E= mc2)
Verified quantum tunnelling
Nobel prize (1956)
Cavendish Lab, Cambridge (1928)
Nuclear fission
fission of heavy elements
Meitner, Hahn
energy release
chain reaction
nuclear weapons
nuclear power
Particle physics (1950s)
Particle accelerators
cyclotron
Cosmic rays
π+ → μ+ + ν
Particle Zoo
Over 100 particles
Quarks (1960s)
new periodic table
p,n not fundamental
symmetry arguments
quarks
new fundamental particles
UP and DOWN
prediction of Stanford experiments 1969
Gell-Mann, Zweig
Quark model
Six different quarks
(u,d,s,c,t,b)
Strong force = quark force
Six leptons
(e, μ, τ, υe, υμ, υτ)
Gen I: all of matter
Gen II, III redundant
Electro-weak unification
Unified field theory
em + w = e-w interaction
Mediated by W and Z bosons
Higgs mechanism to generate mass
Predictions
• Weak neutral currents (1973)
• W and Z gauge bosons (CERN, 1983)
Rubbia, Van der Meer
Nobel prize
The Standard Model (1970s)
Strong force = quark force (QCD)
EM + weak force = electroweak
Matter particles: fermions
Force particles: bosons
QFT: QED
Prediction: W+-,Z0 boson
Detected: CERN, 1983
Standard Model : particles
• Success of QCD, e-w
many questions
Higgs boson outstanding
III. LHC expectations
Higgs boson
120-180 GeV
Set by mass of top quark,
Z boson
Search
Beyond the SM: supersymmetry
Extensions of Standard Model
Grand unified theory (GUT)
Theory of everything (TOE)
Supersymmetry
symmetry of bosons and fermions
improves GUT
circumvents no-go theorems
Theory of Everything
Phenomenology
Supersymmetric particles?
Broken symmetry
Expectations II: cosmology
√ 1. Exotic particles
√ 2. Unification of forces
3. Nature of dark matter?
neutralinos?
4. Matter/antimatter asymmetry?
LHCb
High E = photo of early U
Summary
Higgs boson
Close chapter on SM
Supersymmetric particles
Open next chapter
Cosmology
Nature of Dark Matter
Missing antimatter
Unexpected particles
Revise theory
Epilogue: CERN and Ireland
European Organization for Nuclear Research
World leader
20 member states
10 associate states
80 nations, 500 univ.
Ireland not a member
No particle physics in Ireland