The Big Bang, the LHC and the Higgs Boson

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

2. Overview I.LHC What, How and Why II. Particle physics The Standard Model III.LHCExpectations The Higgs boson and beyond Big Bang cosmology

3. High-energy proton beams Opposite directions Huge energy of collision Create short-lived particles E = mc2 Detection and measurement The Large Hadron Collider No black holes

4. E = 14 TeV λ =1 x 10-19 m Ultra high vacuum Low temp: 1.6 K How LEP tunnel: 27 km 1200 superconducting magnets 600 M collisions/sec

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

6. Cosmology E = kT → T =

7. Particle cosmology

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

9. 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

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

12. 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

13. SF >> em charge indep protons, neutrons short range HUP massive particle Yukawa pion 3 charge states Strong force

14. New particles (1950s) • Cosmic rays Particle accelerators cyclotron π+ → μ + + ν

15. Particle Zoo (1960s) Over 100 particles

16. new periodic table p+,n not fundamental symmetry arguments (SU3 gauge symmetry) SU3 → quarks new fundamental particles UP and DOWN prediction of - Stanford experiments 1969 Quarks (1960s) Gell-Mann, Zweig

17. scattering experiments colour SF = chromodynamics asymptotic freedom confinement infra-red slavery Quantum chromodynamics The energy required to produce a separation far exceedsthe pair production energy of a quark-antiquark pair,

18. Six different quarks (u,d,s,c,t,b) Six leptons (e,μ,τ, υe,υμ,υτ) Gen I: all of matter Gen II, III redundant Quark generations

19. Electro-weak interaction • Gauge theory of em and w interaction Salaam, Weinberg, Glashow • Above 100 GeV • Interactions of leptons by exchange of W,Z bosons • Higgs mechanism to generate mass • Predictions • Weak neutral currents (1973) • W and Z gauge bosons (CERN, 1983) • Higgs boson

20. 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

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

22. Standard Model : 1980s • Experimental success but Higgs bosonoutstanding Key particle: too heavy?

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

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

25. Higgs decay channels • For low Higgs mass mh 150 GeV, the Higgs mostly decays to two b-quarks, two tau leptons, two gluons and etc. • In hadron colliders these modes are difficult to extract because of the large QCD jet background. • The silver detection mode in this mass range is the two photons mode: h   , which like the gluon fusion is a loop-induced process.

26. Decay channels depend on the Higgs mass: Ref: A. Djouadi, hep-ph/0503172

27. A summary plot: Ref: hep-ph/0208209

28. Unified field theory Grand unified theory (GUT): 3 forces Theory of everything (TOE): 4 forces Supersymmetry symmetry of fermions and bosons improves GUT makes TOE possible Phenomenology Supersymmetric particles? Not observed: broken symmetry Expectations: Beyond the SM

29. IV Expectations: cosmology √ 1. Exotic particles:S √ 2. Unification of forces 3. Nature of dark matter? neutralinos? 4. Missing antimatter? LHCb 1. Unification of forces: SUSY 2. SUSY = dark matter? double whammy 3. Matter/antimatter asymmetry? LHCb High E = photo of early U

30. Particle cosmology

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

32. Higgs boson Close chapter on SM Supersymmetric particles Open new chapter: TOE Cosmology Nature of Dark Matter Missing antimatter Unexpected particles? New avenues Summary http://coraifeartaigh.wordpress.com

33. 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