Future Colliders: Opening Windows on the World

1. Future Colliders: Opening Windows on the World Young-Kee Kim The University of Chicago ICFA Seminar September 28 - October 1, 2005 Kyungpook National University, Daegu, Korea

2. Welcome to Korea Calligraphy by my father

3. Accelerators are Powerful Microscopes. They make high energy particle beams that allow us to see small things. seen by high energy beam (better resolution) seen by low energy beam (poorer resolution)

4. Accelerators are also Time Machines. They make particles last seen in the earliest moments of the universe. Energy anti-particle beam energy particle beam energy Particle and anti-particle annihilate. E = mc2

5. Accelerators powerful tools! KEKb, KEK, Tsukuba, Japan PEP-II, SLAC, Palo Alto, USA HERA, DESY, Hamburg, Germany Tevatron, Fermilab, Chicago, USA

6. Many generations of Accelerators created with higher and higher energy given to the beam particle 3/4 of century later Today CDF ~1500 Scientists D0 Tevatron at Fermilab x104 bigger, x106 higher energy 1929 Ernest Lawrence (1901 - 1958)

7. With advances in accelerators, we discovered many surprises. Luminosity (Collision Rate) Time Energy Our field has been tremendously successful in creating and establishing “Standard Model of Particle Physics” answering”what the universe is made of” and “how it works”

8. ~60 years ago ~40 years ago Present atom electron nucleus proton neutron up quark down quark 1 100,000 of human hair 1 10 1 100,000 1 10,000 What is the universe made of? ~90 years ago Rutherford

9. Everything is made of electrons, up quarks and down quarks. Are electrons, up and down quarks the smallest things? Are they made of even smaller things?

10. Elementary Particles and Masses top quark anti-top quark ne nm nt e-mt u d s c b . . . . - - - - - - - - ne nm nt e+mt u d s c b Z W+, W-  gluons (Mass proportional to area shown but all sizes still < 10-19 m) Why are there so many? Where does mass come from?

11. What holds the world together? Beginnings of Unification Gravitational Force Electromagnetic Force Issac Newton (1642 - 1727) James Clerk Maxwell (1831 - 1879)

12. Unification of Gravity and Electromagnetism? Einstein tried to unify electromagnetism and gravity but he failed.

13. radioactive decays Enrico Fermi (1901 - 1954) Weak Force holding proton, nucleus 1 fm = 10-15 m Strong Force gluons

14. Dream of Unification continues! We believe that there is an underlying simplicity behind vast phenomena in nature. Do all the forces become one? At high energy, do forces start to behave the same as if there is just one force, not several forces? Extra hidden dimensions in space?

15. Particle Physics & Cosmology Questions from Astrophysical Observations

16. Everything that we can see Everything is made of electrons, up quarks and down quarks. Galaxies are held together by mass far bigger (x5) than all stars combined. Dark Matter - What is it?

17. Create particles & antiparticles that existed ~0.001 ns after Big Bang E = mc2 particles Accelerators Inflation Big Bang particles anti-particles Where did all antimatter go?

18. BaBar Belle Matter and Anti-Matter Asymmetry (CP Violation)Belle at KEK in Japan and BaBar at SLAC in USdiscovered CP violation in the B system.From their subsequent precision measurements of CP violation we know now that there must be new physics with CP violation in order to explain matter and anti-matter asymmetry in the universe.

19. Not only is the Universe expanding, it is Accelerating!! Where does energy come from? Dark Energy

20. What is the world made of? What holds the world together? Where did we come from? Primitive Thinker

21. 1. Are there undiscovered principles of nature: New symmetries, new physical laws? 2. How can we solve the mystery of dark energy? 3. Are there extra dimensions of space? 4. Do all the forces become one? 5. Why are there so many kinds of particles? 6. What is dark matter? How can we make it in the laboratory? 7. What are neutrinos telling us? 8. How did the universe come to be? 9. What happened to the antimatter? Evolved Thinker From “Quantum Universe”

22. Answering the Questionswith Next Generation of Accelerators (Colliders)

23. today 1970 198019902000201020202030 Energy Frontier Colliders: LEP,SLC ILC CLIC  Collider e+e- e-proton proton-proton HERA LHC TEVATRON Flavor Specific Accelerators: LHCb e+e-(b factory) e+e-(c factory) e+e- (s factory)  PEP-II, KEKB VEPP, CLEO-c, BEPC DANE FNAL, CERN, J-PARC

24. Origin of Mass: There might be something (new particle?!) in the universe that gives mass to particles x x x x x x x x x Coupling strength to Higgs x x x x is proportional to mass Nothing in the universe Something in the universe Electron Z,W Boson Top Quark Higgs Particles:

25. top bottom W Tevatron Run II top top Z Higgs W, Z Tevatron: Improve Higgs Mass Pred. via Quantum Corrections MW (GeV) Mtop (GeV) Current precision measurements favor light Higgs: < ~200 GeV.

26. Tevatron: Improve Higgs Mass Pred. via Quantum Corrections LHC: Designed to discover Higgs with Mhiggs = 100 ~ 800 GeV 130 GeV Higgs L = 100 fb-1 # of events / 0.5 GeV MW (GeV) M(GeV) Mtop (GeV)

27. 5 Discovery Luminosity (fb-1) MW (GeV) Mtop (GeV) MHiggs (GeV) Tevatron: Improve Higgs Mass Pred. via Quantum Corrections LHC: Designed to discover Higgs with Mhiggs = 100 ~ 800 GeV

28. 5 Discovery Luminosity (fb-1) MW (GeV) hard easy Mtop (GeV) MHiggs (GeV) Tevatron: Improve Higgs Mass Pred. via Quantum Corrections LHC: Designed to discover Higgs with Mhiggs = 100 ~ 800 GeV 5 Discovery / Luminosity (fb-1) Will the Tevatron’s prediction agree with what LHC sees?

29. Higgs e+ Z e- Z Higgs d W Z W Z u 115 GeV Higgs is an interesting case! LEP Tevatron LHC But, Higgs sector may be very complex. New physics models expect multiple Higgs particles.

30. Symmetry between fermions (matter) and bosons (forces) “Undiscovered new symmetry” e superparticle ~ e+ e- e e spin 1/2 spin 0 Me ≠ Me super particle particle Higgs Mass: Supersymmetric Extension of Standard Model (SUSY) ~ SUSY solves SM problems: e.g. divergence of Higgs mass, unification. SUSY provides a candidate particle for Dark Matter, solution to matter-antimatter asymmetry, possible connection to Dark Energy? If msuper particle < ~1 TeV, fermion and boson loops cancel and Higgs mass becomes stable.

31. MSSM Tevatron LHC ILC MW (GeV) Mtop (GeV) Higgs in Minimal Supersymmetric Extension of Standard Model LHC tan  MA (GeV) LHC will be the best place to discover Higgs particles!

32. If we discover a “Higgs-like” particle, is it alone responsible for giving mass to W, Z, fermions? Experimenters must precisely measure the properties of the Higgs particle without invoking theoretical assumptions.

33. protonproton (anti-proton!) e- e+ LHC: ILC: • elementary particles • well-defined energy and angular momentum • uses its full energy • can capture nearly full information

34. MHiggs = 120 GeV Number of Events / 1.5 GeV 100 120 140 160 Recoil Mass (GeV) Only possible at the ILC ILC can observe Higgs no matter how it decays! ILC simulation for e+e- Z + Higgs with Z  2 b’s, and Higgs  invisible

35. ILC experiments will have the unique ability to make model-independent tests of Higgs couplings to other particles, at the percent level of accuracy • LEP e+e- collider • Coupling Strength • to Z boson • e : 0.1% • : 0.1% • : 0.1% • : 0.2% q : 0.1% (PDG values) Standard Model Coupling ∞ particle mass Standard Model Coupling ∞ particle mass This sensitivity is sufficient to discover extra dimensions, SUSY, sources of CP violation, or other novel phenomena. Coupling Strength to Higgs Particle Mass (GeV)

36. The Higgs is Different! All the matter particles are spin-1/2 fermions. All the force carriers are spin-1 bosons. Higgs particles are spin-0 bosons. The Higgs is neither matter nor force; The Higgs is just different. This would be the first fundamental scalar ever discovered. The Higgs field is thought to fill the entire universe. Could give some handle of dark energy(scalar field)? Many modern theories predict other scalar particles like the Higgs. Why, after all, should the Higgs be the only one of its kind? Once nature learns how to do something, she does it again! ILC can search for new scalars with precision.

37. HIGGSIf discovered,the Higgs is a very powerful probe of new physics.Hadron collider(s) will discover the Higgs.ILC will use the Higgsas a window viewing the unknown.

38. 1TeV = 103GeV (1016K) 10-11 s Energy Temp Time 2.3 x 10-13 GeV (2.7K) 12x109 y 1019GeV (1032K) 10-41 s 1016GeV (1029 K) 10-38 s Unification We want to believe that there was just one force after the Big Bang. As the universe cooled down, the single force split into the four that we know today.

39. Electromagnetic Force HERA Weak Force f  Beautifully demonstrated at HERA ep Collider at DESY The main missing link is Higgs boson Q2 [GeV2] Unification of electromagnetic & weak forces (electroweak theory) Long term goal since 60’s We are getting there. HERA: H1 + ZEUS

40. Stronger force Higher energy, Shorter distance

41. 13 orders of magnitude higher energy 60 40 20 0 -1 -1 -1 -1 104 108 1012 1016 1020 Q [GeV] The Standard Model fails to unify the strong and electroweak forces.

42. Adding super-partners

43. 60 40 20 0 With SUSY -1 -1 -1 But details count! Precision measurements are crucial. -1 104 108 1012 1016 1020 Q [GeV]

44. Masses also evolve with energy and matter unifies at high energies. ILC ability in measuring SUSY parameters accurately is crucial to extract mass evolution. Discovering Matter Unification in Supersymmetry Mass Squared Energy (TeV) Energy (GeV)

45. Unifying gravity to the other 3 is accomplished by String theory. String theory predicts extra hidden dimensions in space beyond the three we sense daily. Can we observe or feel them? too small? Other models predict large extra dimensions: large enough to observe up to multi TeV scale. With SUSY

46. Tevatron LHC ILC e+ e-  102 10 1 10-1 10-2 e+ e- q q  GN GN Tevatron Sensitivity 2.4 TeV @95% CL Graviton disappears into the ED Events / 50 GeV / 100 fb-1 Production Rate DZero Mee [GeV] Mee [GeV] Collision Energy [GeV] Large Extra Dimensions of Space LHC qq,gg GNe+e-,+- Mee, [GeV] LHC can discover partner towers up to a given energy scale. ILC can identify the size, shape and # of extra dimensions.

47. New forces of nature  new gauge boson Tevatron LHC ILC Events/2GeV 104 103 102 10 1 10-1 qq Z’ e+e- Related to origin of masses Tevatron sensitivity ~1 TeV CDF Preliminary Related to origin of Higgs Vector Coupling Related to Extra dimensions Axial Coupling Mee [GeV] M [GeV] LHC has great discovery potential for multi TeV Z’. Using polarized e+, e- beams, and measuring angular distribution of leptons, ILC can measure Z’ couplings to leptons and discriminate the origins of the new force.

48. Dark Matter (What is the role of Dark Matter in galaxy formation and shapes?) a common bond between astronomers, astrophysicists, and particle physicists Astronomers & astrophysicists over the next two decades using powerful new telescopes will tell us how dark matter has shaped the stars and galaxies we see in the night sky. Only particle accelerators can produce dark matter in the laboratory and understand exactly what it is. The ILC may be a perfect machine to study dark matter.

49. Dark Matter Mass [GeV] 10 100 1000 Interaction Strengh [cm2] 10-44 1043 10-24 Dark Matter in the Lab Underground experiments (CDMS) may detect Dark Matter candidates (WIMPS) from the galactic halo via impact on colliding DM particle on nuclei. LHC may find DM particles (a SUSY particle) through missing energy analyses. (LHC is the best place to discover many of SUSY particles)

50. Dark Matter Mass from Supersymmetry (GeV) Fraction of Dark Matter Density The ILC can determine its properties with extreme detail, allowing to compute which fraction of the total DM density of the universe it makes.