1. LHC: Seeking the Origin of Symmetry Breaking and Mass
何红建
清华大学
Nanchang, April 17-19, 2010.

3. It is beginning of the new start !
LHC: this not the end of the beginning --
It is beginning of the new start ! L H C

4. LHC Runs: 7TeV…10TeV…14TeV……
What discovery expected at LHC ?
What should We do for it ?

5. All Matter(Spin-1/2)+Forces(Spin-1) are discovered in SM!
The only Missing Particle: Higgs Boson H0 (Spin-0).
Higgs Boson gives Masses to All Particles except γ, gluons.

6. All SM Particles: Area of circle ∝ Particle-Mass Only Top, W/Z and Higgs stand out !

7. All spin-1/2 matter particles have
Masses ∝ Arbitrary Yukawa Couplings:
( Mw = g v/2 ) ??

8. SM: (Un)Naturalness of Matter Masses
Only Top & Neutrino masses are Natural
(adding Right-handed Neutrinos):
But, Why All Other Yukawa’s so tiny ?? e.g.,

9. It is often said that LHC is just to find a light fundamental Higgs Boson.
BUT, this is a quite misleading statement －
1. Higgs Boson may be heavy.
2. Higgs may be more than one and charged.
3. Higgs Boson may be composite.
4. Higgs Boson may Not exit at all.
5. Smoking-Gun Signals other than Higgs.

10. ★ Possibility of Heavy Higgs or No Higgs is fully open !
See: Gian Giudice (CERN), talk at Tsinghua on
The two best measurements of
sin2W do not agree :
NO compelling evidence for
Light Higgs Boson even in SM !
★ Possibility of Heavy Higgs or No Higgs is fully open ! 10 10

11. Heavy Higgs vs Precision Data: No Problem !
HJH etal, TopSeesaw Composite Higgs mH ≈ GeV
Top Seesaw Model

12. “Natural” SUSY requires heavier Higgs too !
MSSM
is already
Fine-tuned ! ’
Barbieri et al, ’
Extended SUSYs give:

13. ● Radiative Corrections to Higgs Mass:
Fine-Tuning Problem ?
● Radiative Corrections to Higgs Mass:
● Degree of Fine-Tuning (DFT):

14. Fine-Tuning is a Technical Problem !
14.5TeV
10TeV
7TeV
6.5TeV
3TeV
0.01
0.05
Not strong enough for LHC (ILC) !

15. Mysteries of Mass Origin: What can LHC probe ?ν
10-2 eV
GeV
Origin of Electroweak Symmetry Breaking:
-- Why are (W, Z) Massive but photon Massless ?
Does t-Quark conspire Electroweak Symmetry Breaking:
-- Why is t-Quark Mass so Close to W/Z Masses ?
Why is Neutrino Mass so tiny ? → Seesaw Mechanism !

16. in High Energy Scattering !!!!!
Origin of Electroweak Symmetry Breaking: Why Higgs Boson (light or heavy) at all ?!?
Real Physics Problem
with Electroweak Symmetry Breaking is
Unitarity Violation
in High Energy Scattering !!!!!

17. Unitarity of WLWL → WLWL: Electroweak Symmetry Breaking Scale
No Way to Escape this Physics Bound !!!
Much Stronger & More Robust than Fine-tuning bound!

18. 0.7

19. A New Way to Restore Unitarity: Higgsless Theory !!!
Crucial Observation:
New Spin-1 Gauge Bosons can Replace
Spin-0 Higgs to Restore Unitarity !!!
Chivukula,Dicus,He, 2001: New Gauge Bosons from 5d-KK
Chivukula,He, 2002: New Gauge Bosons from 4d-Deconstruction
and 19 series papers in

23. LHC Signals for Higgsless W1 Boson: pp→W1 Z→WZZ→jj+4Leptons
pp→jjWZ (including WZ─W1*→WZ→3l+nu)
HJH, YPK,YHQ, BZ & MSU
arXiv:

24. LHC Sensitivity for W1 in WZZ & jjWZ Channels:
HJH, YPK, YHQ, BZ & MSU
LHC Sensitivity for W1 in WZZ & jjWZ Channels:

25. Does top-Quark Conspire Electroweak Symmetry Breaking ??
Why is t-Quark Mass
so Close to W/Z Masses ?
Does top-Quark Conspire Electroweak Symmetry Breaking ??

26. 50 Years Ago
Lee and Yang, 1956
Parity
Ni60

27. We reveal the Intrinsic Connection between
Spontaneous Parity Violation (SPV) and
Electroweak Symmetry Breaking (EWSB)
SPV Scale is tied to TeV Scale
SPV Induces EWSB (W,Z Masses)
as Uniquely fixed by Top-quark Mass = 174 GeV

28. Predictions: A Sample Higgs Spectrum：
E.g.

29. LHC Discovery: Luminosity vs Higgs Mass

30. Signals at the LHC: and
pp (gb) → t H+ → t t b.
pp → WR → bbW

31. Scales of Fermion Mass Generation
New Physics that LHC canNot do ?
Scales of Fermion Mass Generation

32. Exciting Future: After LHC !!!

33. New Physics that LHC cannot do: Neutrino Mixing, CP-Violation, Matter-Antimatter Asymmetry…

34. Daya Bay’s Physics Potential on θ13 is Non-trivial to justify:

35. Our Theory Prediction gives strongest support for Daya Bay !!!
Ge, He, Yin, JCAP(2010),

36. than we naively thouhght !! Many New Scales ? Many New Forces ?
Nature may be
more complicated and
more interesting
than we naively thouhght !!
Many New Scales ?
Many New Forces ?
Is Gravity Emergent?
Is M_Planck fundamental?
KeV
TeV
1019 GeV

37. Keep Your Mind Fully Open !!!
2010 ─ 2030
Keep Your Mind Fully Open !!!

38. Thank You !

39. Backup Slides

41. 4 Fundamental Forces evolve back with Time/Temperature(Energy):Unification?

42. New Physics at TeV Scale ?
Hierarchy/Fine-Tuning Problem ?
→ Not strong enough !
Unification ?
→ Many possible realizations !
Light Higgs ?
→ Not enforced by data !
Then,
WHAT best justifies TeV Scale? …

44. Fine-Tuning Problem ? →No Fine-Tuning for MH around 300GeV !
SM Higgs Mass 1-Loop Quadratical Divergence:
Quadratical Divergence vanishes if
→No Fine-Tuning for MH around 300GeV !

45. SM Higgs Potential runs into more serious Vacuum Energy Problem even at TREE-Level: (eg, S.Weinberg, 1989)
Neutrino Mass !
<ρ> = Vmin – λv4/4
= Vmin －O(100GeV)4 == (2∙10-3eV)4
→ 55 Orders of Magnitude Fine-tuning !
Soft Breaking SUSY faces the same problem!
So, WHY do we care 1% Tuning at 1-Loop?!

46. RSC, DAD, HJH

48. VLHC: http://vlhc.org (50-200TeV)

49. Lessons:
(1) A Good Theory ! (2) Vigorous Experiments !! (3) Courage !!!

50. Origin of Masses, TeV Scale & LHC
Conclusions:
Origin of Masses, TeV Scale & LHC
Why TeV Scale: ( Strongest Bound is from Unitarity ! )
Unitarity of WLWL → WLWL ( < 1.2TeV )
Justify 1TeV Scale for LHC + ILC !!
What New Physics: Higss vs HiggsLess + SPV
Light Higgs or Heavy Higgs or HiggsLess;
4d Deconstruction vs Extra-dim →Unitarity !
New Spin-1 Gauge Bosons Restore Unitarity !!
How to Observe New Gauge Bosons: Signals vs Bkgnds
LHC is very Promising to find W1 by !!!