The Big Bang, the LHC and the Higgs Boson
Dr Cormac O’ Raifeartaigh (WIT)
Overview
I. LHC
What, How and Why
II. Particle physicsThe Standard Model
III. LHC Expectations
The Higgs boson and beyond
Big Bang Cosmology
The Large Hadron Collider
No black holes
High-energy proton beams
Opposite directions
Huge energy of collision
E = mc2 Create short-lived particles
Detection and measurement
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 theory
Theoretical physics expected collisions
Experimental physicists experiments
Engineers detector design
Computer scientists world wide web
Software engineers GRID
Particle physics (1930s)
• atomic nucleus (1911)
• most of atom empty
• electrons outside
• strong nuclear force?
Periodic Table: determined by protons
• inside the nucleus proton (1909) neutron (1932)
Four forces of nature Force of gravityHolds cosmos togetherLong range
Electromagnetic force Holds atoms together
Strong nuclear force Holds nucleus together
Weak nuclear force: Radioactivity
The atom
Splitting the nucleus (1932)
Cockcroft and Walton: linear accelerator
Accelerator used to split the nucleus
Nobel prize (1956)
H1 + Li3 = He2 + He2
Verified mass-energy (E= mc2)Verified quantum tunnelling
Cavendish Lab, Cambridge (1928)
Nuclear fission
fission of heavy elements Meitner, Hahn
energy release
chain reaction
nuclear weapons
nuclear power
Particle physics (1950s)
Cosmic raysParticle accelerators
cyclotron π + → μ + + ν
Particle Zoo
Over 100 particles
Quarks (1960s)
new periodic tablep,n not fundamental symmetry arguments
quarks
new fundamental particlesUP and DOWNprediction of -
Gell-Mann, ZweigStanford experiments 1969
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 MeerNobel prize
The Standard Model (1970s)
Strong force = quark force (QCD)
EM + weak force = electroweak
Matter particles: fermions
Force particles: bosonsQFT: 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 ModelGrand unified theory (GUT) Theory of everything (TOE)
Supersymmetrysymmetry of bosons and fermionsimproves GUTcircumvents no-go theoremsTheory 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
SummaryHiggs bosonClose chapter on SM
Supersymmetric particlesOpen next chapter
CosmologyNature of Dark MatterMissing antimatter
Unexpected particlesRevise theory
Epilogue: CERN and Ireland
World leader
20 member states
10 associate states
80 nations, 500 univ.
Ireland not a member
No particle physics in Ireland
European Organization for Nuclear Research