The Big Bang, the LHC and the God Particle

1. The Big Bang, the LHC and the God Particle Dr Cormac O’Raifeartaigh (WIT) The Big Bang, the LHC and the God Particle Cormac O’Raifeartaigh (WIT)

2. Overview I.LHC What, why, how II. A brief history of particles From atoms tothe Standard Model III.LHCExpectations The God particle Beyond the Standard Model Cosmology at the LHC

3. Particle accelerator Head-on collision Huge energy density Create short-lived particles E = mc2 Detection The Large Hadron Collider (CERN) No black holes

4. Ultra high vacuum Low temp: 1.6 K v = speed of light E = 14 TeV (2.2 µJ) How LEP tunnel: 27 km Superconducting magnets 600 M collisions/sec (1.3 kW)

5. I. Explore fundamental constituents of matter Investigate inter-relation of forces that hold matter together II. Study early universe Highest energy since BB Why • Puzzle of antimatter • Puzzle of dark matter • T = 1019 K • t = 1x10-12 s • V = football

6. Cosmology E = kT → T =

7. Particle detectors • 4 main detectors • CMS multi-purpose • ATLASmulti-purpose • ALICEquark-gluon plasma • LHC-bantimatter decay

8. Particle detectors • Tracking device measures momentum of charged particle • Calorimeter measures energy of particle by absorption • Identification detector measures velocity of particle by Cherenkov radiation

9. 9 accelerators • recycling • velocity increase? K.E = 1/2mv2

10. Applications • Computer science Data analysis • World Wide Web Platform for sharing data • Hospital physics Accelerators Positron Emission Tomography (PET) • GRID Distributed computing Tim Berners-Lee

11. II Particle physics (1930s) • electron (1895) • atom (1909) • nuclear atom (1911) • Rutherford Backscattering • proton(1918) • what holds nucleus together? • what holds electrons in place? • what causes radioactivity? • neutron (1932)

12. Protons and the Periodic Table • Fundamental differences • no. protons in nucleus • Determines no. electrons • Determines chemical properties what holds nucleus together?

13. strong force >> em charge indep (p+, n) short range Heisenberg Uncertainty massive particle 3 charge states Strong force Yukawa Yukawa pion (π)

14. 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: Beta decay The atom

15. New particles (1950s) Cosmic rays Particle accelerators LINACS (Walton) synchrotrons π+ → μ+ + ν

16. Particle Zoo (1950s, 1960s) Over 100 particles

17. p not fundamental new periodic table symmetry arguments new fundamental particles quarks Up, down, strange prediction of - Quarks (1960s theory) Gell-Mann, Zweig

18. Stanford experiments 1969 Scattering experiments Similar to RBS SF = interquark force! defining property = colour confinement infra-red slavery Quarks (experiment, 1970s) The energy required to produce a separation far exceedsthe pair production energy of a quark-antiquark pair

19. 30 years experiments Six different quarks (u,d,s,c,t,b) Six leptons (e,μ,τ, υe,υμ,υτ) Gen I: all of ordinary matter Gen II, III redundant? Quark generations (1970s –1990s)

20. Electro-weak force (1970s) • Electromagnetic + weak forces = e-w force • Single interaction above 100 GeV • Mediated by new particles • Higgs mechanism to generate mass • Predictions • W and Z gauge bosons (CERN, 1983) • Higgs boson (the God particle) Rubbia and van der Meer Nobel prize 1984

21. The Origin of Mass The strong nuclear force cannot explain the mass of the electron though… Or very heavy quarks top mass = 175 proton mass The Higgs Boson We suspect the vacuum is full of another sort of matter that is responsible – the higgs…. a new sort of matter – a scalar? To explain the W mass the higgs vacuum must be 100 times denser than nuclear matter!! It must be weak charged but not electrically charged

22. Strong force = quark force (QCD) EM + weak force = electroweak Matter particles: fermions Force particles: bosons The Standard Model (1970s) • Prediction: W+-,Z0 boson • Detected: CERN, 1983

23. Standard Model: 1980-1990s • experimental success but Higgs bosonoutstanding key particle: too heavy?

24. Higgs boson Determines mass of other particles 120-180 GeV Set by mass of top quark, Z boson Search…surprise? III LHC expectations (SM)

25. Main production mechanisms of the Higgs at the LHC Ref: A. Djouadi, hep-ph/0503172

26. Higgs search: summary Ref: hep-ph/0208209

27. Unified field theory Grand unified theory (GUT): 3 forces Theory of everything (TOE): 4 forces Supersymmetry symmetry of fermions and bosons improves GUT (circumvents no-go theorems) gravitons: makes TOE possible LHC Supersymmetric particles? Extra dimensions? Expectations II: Beyond the SM

28. Expectations III: Cosmology • Superforce: SUSY particles? 2. SUSY = dark matter? neutralinos? double whammy 3. Missing antimatter ? LHCb High E = photo of early U

29. Tangential to ring B-meson collection Decay of b quark, antiquark CP violation (UCD group) LHCb (UCD) • Where is antimatter? • Asymmetry in M/AM decay • CP violation

30. Higgs boson (God particle) Close chapter on SM Supersymmetric particles Open chapter on unification Cosmology Missing antimatter Nature of dark matter Surprises New dimensions - string theory? Summary Further reading: ANTIMATTER

31. World leader 20 member states 10 associate states 80 nations, 500 univ. Ireland not a member Epilogue: CERN and Ireland European Organization for Nuclear Research No particle physics in Ireland…..almost