2. http://www.adams-institute.ac.uk Ken.Peach@adams-institute.ac.uk Introduction to Particle Physics Saturday July 3 rd 2010 APPEAL, Oxford Prof. Ken Peach

3. Ken PeachJohn Adams Institute3 July 20102 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 Institute3 July 20103 An important equation  U=0 “U” is “the equation of state of the Universe”! Of course, we do not know what U is … but we can try to find out what U contains U = U known + U unknown U known is the result of experiment U unknown is the object of theory

5. Ken PeachJohn Adams Institute3 July 20104 Probing Inner Space 3 basic ways Look at it Heat it Smash it Wavelength Temperature TEnergy E h c/ =kTE=

6. Ken PeachJohn Adams Institute3 July 20105 Remarkable comment All three the same fundamental physics! Uses ‘light’ Uses ‘heat’ TUses ‘probe’ E h c/ =kTE= Photons ‘Photons’        

7. Ken PeachJohn Adams Institute3 July 20106 Scattered electronScattered lepton ConstituentsConstituents Particle Hammers proton electron { ProtonfragmentsProtonfragments Scattered ‘parton’ PhotonPhoton, W, Z

8. Ken PeachJohn Adams Institute3 July 20107 The Particle Physicist’s “Periodic Table” u u d d d u Proton Neutron The Chemist’s Periodic Table

9. Ken PeachJohn Adams Institute3 July 20108 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

10. Ken PeachJohn Adams Institute3 July 20109 The Standard Model … After G Barbieri, ICHEP04

11. Ken PeachJohn Adams Institute3 July 201010 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!

12. Ken PeachJohn Adams Institute3 July 201011 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 )

13. Ken PeachJohn Adams Institute3 July 201012 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

14. Ken PeachJohn Adams Institute3 July 201013 High Precision Frontier Known phenomena studied with high precision may show inconsistencies with theory High Energy Frontier New phenomena (new particles) created when the “usable” energy > mc 2 [×2] How will we do it? 2 routes to new knowledge about the fundamental structure of the matter

15. Ken PeachJohn Adams Institute3 July 201014 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?

16. Ken PeachJohn Adams Institute3 July 201015 Arial view of the CERN site © CERN

17. Ken PeachJohn Adams Institute3 July 201016 ALEPH A detector for LEP Physics © CERN & PPARC

18. Ken PeachJohn Adams Institute3 July 201017 Some events Ze+e-Ze+e- Z+-Z+- Z   +  - ZqqZqq

19. Ken PeachJohn Adams Institute3 July 201018 More (complicated) events Z   +  -  Z  qqg Z  4 ‘jets’ e+e-W+W-e+e-W+W-

20. Ken PeachJohn Adams Institute3 July 201019 The Standard Model Where are we?  ? ? Neutrino Oscillations need a neutrino mass term  i  M ij  j Why are the strong, electromagnetic and weak interactions like they are?

21. Ken PeachJohn Adams Institute3 July 201020 New physics scale Energy evolution of the interaction strength 30 60 50 40 20 10 0  i -1 Log 10 [Energy Scale (GeV)] 357911131517 No Grand Unification Unification ! “e/m” “weak” “strong” Supersymmetry?  3 -1  2 -1  1 -1

22. Ken PeachJohn Adams Institute3 July 201021 The Large Hadron Collider ATLAS CMS

23. Ken PeachJohn Adams Institute3 July 201022 ATLAS Z 0 event

24. Ken PeachJohn Adams Institute3 July 201023 ATLAS W +  e + event

25. Ken PeachJohn Adams Institute3 July 201024 ATLAS 4-jet event

26. Ken PeachJohn Adams Institute3 July 201025 ATLAS – a potential problem

27. Ken PeachJohn Adams Institute3 July 201026 A CMS event

28. Ken PeachJohn Adams Institute3 July 201027 First data Before discovering new things, need to “discover” the old things, just to be sure that we understand the new instruments.

29. Ken PeachJohn Adams Institute3 July 201028 From microscopes to telescopes …

30. Ken PeachJohn Adams Institute3 July 201029 The biggest challenge … the Creation of the Universe! The Big Bang

31. Ken PeachJohn Adams Institute3 July 201030 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

32. Ken PeachJohn Adams Institute3 July 201031 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

33. Ken PeachJohn Adams Institute3 July 201032 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!

34. Ken PeachJohn Adams Institute3 July 201033

35. Ken PeachJohn Adams Institute3 July 201034 What is the Vacuum? Dictionary Definitions: An entirely (or very nearly) empty space Chambers 20 th Century 1.Emptiness of space; space unoccupied by matter 2.(a) A space entirely empty of matter (b) A space empty of air, esp. one from which the air has been artificially withdrawn 3.An empty space; a portion of space (left) unoccupied or unfilled with the usual or natural contents OED My definition: That which remains when everything else is taken away

36. Ken PeachJohn Adams Institute3 July 201035 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!

37. Ken PeachJohn Adams Institute3 July 201036 Origin of Mass ? m=0, v = speed of light No Higgs field 00 00H H H H V 0 With Higgs field

38. Ken PeachJohn Adams Institute3 July 201037 … but look what we have done to ‘empty space’ It is filled with these ‘fields’

39. Ken PeachJohn Adams Institute3 July 201038 The vacuum … 1.‘knows’ about all particles that exist …and that can exist 2.‘knows’ about all forces that exist …and that can exist 3.has more energy (x 10) than all normal matter in the universe …we are cosmologically less significant than ‘empty space’ 4.created the Universe …as we know it today 5.made more matter than antimatter … and so created the conditions that allow us to exist! Remember The vacuum is the most complicated thing in the Universe