1 / 50

何红建 清华大学

LHC: Seeking the Origin of Symmetry Breaking and Mass LHC: 探索对称性破缺与质量起源. 何红建 清华大学. Nanchang, April 17-19, 2010. LHC: this not the end of the beginning --. It is beginning of the new start !. L. H. C. LHC Runs: 7 TeV… 10 TeV… 14 TeV……. What discovery expected at LHC ?

shannon-dominguez
Download Presentation

何红建 清华大学

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LHC: Seeking the Origin of Symmetry Breaking and Mass LHC: 探索对称性破缺与质量起源 何红建 清华大学 Nanchang, April 17-19, 2010.

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

  3. LHC Runs: 7TeV…10TeV…14TeV…… What discovery expected at LHC ? What should Wedo for it ?

  4. 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.

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

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

  7. SM: (Un)Naturalness of Matter Masses • Only Top & Neutrino masses are Natural (adding Right-handed Neutrinos): • But,WhyAll Other Yukawa’sso tiny ?? e.g.,

  8. It is often said that LHC is just to finda 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.

  9. See: Gian Giudice (CERN), talk at Tsinghua on 3-28-2010 The two best measurements of sin2W do notagree : NO compelling evidence for Light Higgs Boson even in SM ! ★Possibility of Heavy Higgs or No Higgs is fully open ! 10

  10. Heavy Higgs vs Precision Data:No Problem ! HJH etal, TopSeesaw Composite Higgs mH ≈ 400-500GeV Top Seesaw Model

  11. “Natural” SUSY requires heavier Higgs too ! MSSM is already Fine-tuned ! ’ Barbieri et al, 1004.2256 ’ Extended SUSYs give:

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

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

  14. 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 ? →SeesawMechanism !

  15. Origin of Electroweak Symmetry Breaking:Why Higgs Boson (light or heavy) at all ?!? Real Physics Problem withElectroweak Symmetry Breakingis Unitarity Violation inHigh Energy Scattering!!!!!

  16. Unitarity of WLWL → WLWL: Electroweak Symmetry Breaking Scale No Way to Escape this Physics Bound !!! MuchStronger & More RobustthanFine-tuning bound!

  17. 0.7

  18. A New Way to RestoreUnitarity: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 2003-2009

  19. LHC Signals for Higgsless W1 Boson: • pp→W1Z→WZZ→jj+4Leptons • pp→jjWZ (including WZ─W1*→WZ→3l+nu) HJH, YPK,YHQ, BZ & MSU arXiv:0708.2588

  20. HJH, YPK, YHQ, BZ & MSU LHC Sensitivity for W1in WZZ & jjWZ Channels:

  21. Does top-Quark ConspireElectroweak Symmetry Breaking ?? Whyist-Quark Mass so Close toW/Z Masses ?

  22. 50 Years Ago Lee and Yang, 1956 Parity Ni60

  23. We reveal the Intrinsic Connection between Spontaneous Parity Violation (SPV) and Electroweak Symmetry Breaking (EWSB) • SPV Scaleis tied toTeV Scale • SPV InducesEWSB (W,Z Masses) as Uniquely fixed by Top-quark Mass = 174 GeV

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

  25. LHC Discovery: Luminosity vs Higgs Mass

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

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

  28. Exciting Future: After LHC !!!

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

  30. Daya Bay’s Physics Potential on θ13is Non-trivial to justify:

  31. Our Theory Prediction givesstrongest support forDaya Bay !!! Ge, He, Yin, JCAP(2010), 1001.0940

  32. 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? 1019 GeV KeV TeV

  33. 2010 ─ 2030 Keep Your MindFully Open !!!

  34. Thank You !

  35. Backup Slides

  36. 4 Fundamental Forces evolve back withTime/Temperature(Energy):Unification?

  37. 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?…

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

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

  40. RSC, DAD, HJH

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

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

  43. 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:Signalsvs Bkgnds LHC is very Promising to find W1by 2011-12 !!!

More Related