2. http://www.adams-institute.ac.uk Ken.Peach@adams-institute.ac.uk Particle Physics: Adventures in the Quantum Wonderland Ken Peach (John Adams Institute for Accelerator Science) Talk to the Purbeck Science and Technology Group 3 rd April 2008

3. Ken PeachJohn Adams Institute03 April 20082 What is ‘Particle Physics’? The Particle Physics (or ‘High Energy Physics’) ‘Mission’ –identify the fundamental constituents of matter –describe the interactions (forces) between them A long and honourable history –Constituents ‘Earth, Fire, Air and Water’ of the Greeks ‘Atoms’ of Democretus and Lucretius –Forces Gravity (Newton) Electricity (Coulomb) A significant achievement of the 20 th century –The electron (JJ Thomson, 1897) –The top quark (CDF & D0, 1995) –QED, QCD, electro-weak (gravity)

4. Ken PeachJohn Adams Institute03 April 20083 From the Big Bang to today © CERN Particle Physics

5. Ken PeachJohn Adams Institute03 April 20084 Probing Inner Space 3 basic ways Look at it Heat it Smash it Wavelength Temperature TEnergy E h c/ =kTE=

6. Ken PeachJohn Adams Institute03 April 20085 Remarkable comment All three the same fundamental physics! Uses ‘light’ Uses ‘heat’ TUses ‘probe’ E h c/ =kTE= Photons ‘Photons’        

7. Ken PeachJohn Adams Institute03 April 20086 Quantum Information

8. Ken PeachJohn Adams Institute03 April 20087 Scattered electronScattered lepton ConstituentsConstituents Particle Hammers proton electron { ProtonfragmentsProtonfragments Scattered ‘parton’ PhotonPhoton, W, Z

9. Ken PeachJohn Adams Institute03 April 20088 The Particle Physicist’s “Periodic Table” u u d d d u Proton Neutron The Chemist’s Periodic Table

10. Ken PeachJohn Adams Institute03 April 20089  photon e electron e e-neutrino d down up uI Leptons Quarks Particles and their Interactions © Brian Foster

11. Ken PeachJohn Adams Institute03 April 200810 … but there is more … the V event Opening angle 66.6 °; +ve track 340±100 MeV/c; +ve track 350±150 MeV/c Mass (assuming secondaries are pions) ~ 490 ± 90 MeV/c 2

12. Ken PeachJohn Adams Institute03 April 200811  photon Generations of matter Generations of matter  muon   -neutrino s strange c charm II e electron e e-neutrino d down up uI Leptons Quarks Particles and their Interactions © Brian Foster  tau   -neutrino b bottom t top III

13. Ken PeachJohn Adams Institute03 April 200812 The Neutral Kaon System The neutral kaon is a meson made of a  down-quark and an antistrange-quark The neutral antikaon is made of an  antidown-quark and a strange-quark d s ds

14. Ken PeachJohn Adams Institute03 April 200813  photon Generations of matter Generations of matter  tau   -neutrino b bottom t top III  muon   -neutrino s strange c charm II e electron e e-neutrino d down up uI Leptons Quarks Particles and their Interactions © Brian Foster Each with its own ‘antiparticle’

15. Ken PeachJohn Adams Institute03 April 200814 Forces LegoParticle Force g q q  q or + q or - Z q or + or q or - or W+W+ u, c, t or + d, s, b or Gluon Photon u c t d s b  u  c  t  d  s  b

16. Ken PeachJohn Adams Institute03 April 200815 More Forces LegoForce Force g Gluon g g ,Z W+W+ W-W- g g g g and other 3- and 4- particle interactions

17. Ken PeachJohn Adams Institute03 April 200816 Force Carriers Z Z boson W W boson  photon g gluon Generations of matter Generations of matter  tau   -neutrino b bottom t top III  muon   -neutrino s strange c charm II e electron e e-neutrino d down up uI Leptons Quarks Particles and their Interactions © Brian Foster

18. Ken PeachJohn Adams Institute03 April 200817 The problem of mass The Standard Model relies on –Relativity +Quantum mechanics Relativistic Quantum Field Theory –Each particle has an associated all-pervasive ‘field’  (x,t) –Symmetry There is no ‘special place’ in the Universe There are no ‘preferred directions’ in space-time There is ‘local autonomy’ for the particle fields –Produces a beautiful theory –… with all particles massless! Adding mass violates the beautiful symmetries The Higgs Mechanism –Fill space-time with another (Higgs) field  (x,t) A new type of force with special properties –… that give mass to the particles …and leaves a signature behind …– the Higgs Boson!

19. Ken PeachJohn Adams Institute03 April 200818 … but ‘empty space’ is now very busy It is filled with the ‘Higgs fields’

20. Ken PeachJohn Adams Institute03 April 200819 Origin of Mass ? m=0, v = speed of light No Higgs field 00 00H H H H V 0 With Higgs field

21. Ken PeachJohn Adams Institute03 April 200820 HiggsBosonHiggsBoson? Force Carriers Z Z boson W W boson  photon g gluon Generations of matter Generations of matter  tau   -neutrino b bottom t top III  muon   -neutrino s strange c charm II e electron e e-neutrino d down up uI Leptons Quarks Particles and their Interactions Each with its own ‘antiparticle’ © Brian Foster

22. Ken PeachJohn Adams Institute03 April 200821 The Standard Model The Parameters 6 quark masses –m u, m c, m t –m d, m s, m b 3 lepton masses –m e, m , m  2 vector boson masses –M w, M Z (m , m g =0) 1 Higgs mass –Mh–Mh 3 coupling constants –G F, ,  s 3 quark mixing angles –  12,  23,  13 1 quark phase – –  Neutrino masses set to 0!

23. Ken PeachJohn Adams Institute03 April 200822 The Standard Model in action Take a process e + e -     - 4  2 /3s a is the fine structure constant s is the (C.of.M Energy) 2 (neglecting masses and √s<<M Z )

24. Ken PeachJohn Adams Institute03 April 200823 How good is the Standard Model? 18 measurements 5 free parameters  2 = 18.1/13 d.o.f. 3 > 1  1 > 2  Almost too good!

25. Ken PeachJohn Adams Institute03 April 200824 What still remains to be done? The origin of mass –“Hunting the Higgs” The origin of the forces –Strong, electro-weak & gravity, or just one fundamental force The origin of “Dark Matter” (& Dark Energy) –Accounting for most of the mass of the universe The origin of cosmological matter-antimatter asymmetry –Why does the universe today consist only of matter, not equal amounts of matter and antimatter Fundamental questions in particle physics that are equally fundamental questions in cosmology

26. Ken PeachJohn Adams Institute03 April 200825 How do we know all this? © CERN Matter & antimatter annihilate into energy Go to the highest energy See what happens Energy (MeV) 0.000001 0.1 100,000 10,000 1,000 100 10 1 e u,d s  c b  W Z t leptons quarks Weak Bosons Higgs?

27. Ken PeachJohn Adams Institute03 April 200826 CERN from Space

28. Ken PeachJohn Adams Institute03 April 200827 Arial view of the CERN site © CERN

29. Ken PeachJohn Adams Institute03 April 200828 … and what is beneath the surface © CERN

30. Ken PeachJohn Adams Institute03 April 200829 ALEPH A detector for LEP Physics © CERN & PPARC

31. Ken PeachJohn Adams Institute03 April 200830 Some events Ze+e-Ze+e- Z+-Z+- Z   +  - ZqqZqq

32. Ken PeachJohn Adams Institute03 April 200831 More (complicated) events Z   +  -  Z  qqg Z  4 ‘jets’ e+e-W+W-e+e-W+W-

33. Ken PeachJohn Adams Institute03 April 200832 The Large Hadron Collider ATLAS CMS

34. Ken PeachJohn Adams Institute03 April 200833 New physics scale Note: The vacuum ‘knows’ about particles already found … and all of the particles still to be found! 30 60 50 40 20 10 0  i -1 Log 10 [Energy Scale (GeV)] 357911131517 No Grand Unification Unification ! “e/m” “weak” “strong” Supersymmetry? Evolution of the strength of the interactions with increasing energy  3 -1  2 -1  1 -1

35. Ken PeachJohn Adams Institute03 April 200834 From microscopes to telescopes …

36. Ken PeachJohn Adams Institute03 April 200835 The biggest challenge … the Creation of the Universe! The Big Bang

37. Ken PeachJohn Adams Institute03 April 200836 From the Big Bang to today © CERN

38. Ken PeachJohn Adams Institute03 April 200837 Galaxy formation The state of the Universe 10 -15 10 -12 10 -9 10 -6 10 -3 1 10 3 10 6 10 9 10 12 10 15 10 18 Time (sec) 1 10 4 10 8 10 12 10 16 10 20 Temperature ( o K) The Big Bang Biology Solar System forms Atoms form Chemistry begins Today 3 x 10 18 s 3 o K Neutron lifetime nucleosynthesis Protons, neutrons & nuclei form W & Z production Particle physics

39. Ken PeachJohn Adams Institute03 April 200838 Particle Physics and Cosmology The Higgs potential … Primordial ripples Fundamental mode Geometry Potential wells compression baryons Rarefaction… etc WMAP Data, Verde, LP03 the particle spectrum … and the unknown … Illustrations from Muryama, LP03 should explain

40. Ken PeachJohn Adams Institute03 April 200839 Dark vesus “Light” Matter Distributions Normal Matter Dark Matter

41. Ken PeachJohn Adams Institute03 April 200840 More Dark Matter

42. Ken PeachJohn Adams Institute03 April 200841 The Cosmological Budget -  From the ‘flatness’ of space   1 From the observed galaxies & nucleosynthesis  B   0.01 From rotation curves of galaxies & large scale structure  Matter   0.34 Rate of expansion  Space   0.65

43. Ken PeachJohn Adams Institute03 April 200842 Summary We have a wonderful “model” to describe the particle world –but it is not a theory it describes but does not explain –and has “missing links” What about gravity? Why 3 forces? Why 3 generations? How does the matter-antimatter asymmetry arise? Why 3 space and 1 time dimension? Are there more dimensions? … (fortunately) still a lot to learn!

44. Ken PeachJohn Adams Institute03 April 200843 http://www.physics.ox.ac.uk/users/peachk/ Thank You