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 T he Higgs boson and beyond Big Bang Cosmology

The Large Hadron Collider N o black holes High-energy proton beams Opposite directions Huge energy of collision E = mc 2 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 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 physicistsexperiments Engineersdetector design Computer scientistsworld 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 gravity Holds cosmos together Long 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) H 1 + Li 3 = He 2 + He 2 Verified mass-energy (E= mc 2 ) 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 rays Particle accelerators cyclotron 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  - Gell-Mann, Zweig Stanford experiments 1969

Quark model Six different quarks (u,d,s,c,t,b) Strong force = quark force Six leptons (e, μ, τ, υ e, υ μ, υ τ ) 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 +-,Z 0 boson Detected: CERN, 1983

Standard Model : particles Success of QCD, e-w many questions Higgs boson outstanding

III. LHC expectations Higgs boson 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 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