1. KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association Institut für Experimentelle Kernphysik www.kit.edu CMS Observation of a new boson at the LHC and its implications for the origin of mass. Wim de Boer (for the CMS Collaboration)

2. 2 Wim de Boer Time and Matter, Venice, March 2013 Outline  Evidence for a Higgs particle in CMS  Is it Peter´s Higgs or just a Higgs?  What it has to do with the “origin of mass” in the universe?  What is the Higgs boson good for?  What is so special about observed Higgs particle?

3. 3 Wim de Boer Time and Matter, Venice, March 2013 The LHC Two rings with 1232 superconducting dipoles and 858 quadrupoles, 26,7 km circumference max. 2808 proton bunches, 40 MHZ collision rate, ~10 11 Protons / bunch ~500 million pp collisions / s at 7 & 8 TeV centre of mass energy Bending magnets Cavities for acceleration

4. 4 Wim de Boer Time and Matter, Venice, March 2013 Design Criteria for the CMS Experiment  Very good muon identification and momentum measurement. H  ZZ, with Z   Most precise photon detector. H   Powerful inner tracking for electron identification. H  ZZ, Z  ee  Hermetic calorimetry for missing E T signatures: H  WW, W  First conceptual design of a “Compact Muon Solenoid” (CMS) was presented in Aachen (1990) based on a 4 Tesla solenoid. 4 From M. Della Negra, Wess-prize recipient (with P. Jenny), 2013, Karlsruhe

5. 5 Wim de Boer Time and Matter, Venice, March 2013 Compact Muon Solenoid (CMS) Experiment Silicon Detectors Measure tracks left by charged particles Silicon Detectors Measure tracks left by charged particles Calorimeters Absorb particles and measure their energy Calorimeters Absorb particles and measure their energy Muon Detectors Identify and measure muons that penetrate Muon Detectors Identify and measure muons that penetrate 3.8 T Magnet Bend tracks of charged particles 3.8 T Magnet Bend tracks of charged particles z 0 (center)

6. 6 Wim de Boer Time and Matter, Venice, March 2013 CMS Collaboration 1400 Physicists 600 Graduate students 175 Institutes 38 Countries

7. 7 Wim de Boer Time and Matter, Venice, March 2013 Assembly in the surface hall Waiting for the cavern to be ready

8. 8 Wim de Boer Time and Matter, Venice, March 2013 Descent of the central wheel (2000 tons)

9. 9 Wim de Boer Time and Matter, Venice, March 2013 Heart of CMS: all silicon tracker (200 m 2 !) 66 million silicon pixels: 100  150 µm 2 9.3 million silicon microstrips: 80µm - 180µm. ~200 m 2 of active silicon area (cf ~ 2m 2 in LEP detectors) ~13 precise position measurements (15 µm ) per track. 9 Pile-up: many collisions pro bunch crossing

10. 10 Wim de Boer Time and Matter, Venice, March 2013 78 reconstructed vertices in high pile-up run

11. 11 Wim de Boer Time and Matter, Venice, March 2013 Dimuon mass resolution 24 years of e+e- machines 24 hours of LHC

12. 12 Wim de Boer Time and Matter, Venice, March 2013 LHC Luminosity New records: – centre-of-mass energy 8 TeV – peak luminosity 0.77∙ 10 34 / cm² /sec – best week ∫L=1.35 fb -1 ( 75% design luminosity @ half energy & half # of bunches) summer conferences 2012 HCP 2012 (delivered) TAM 2013

13. 13 Wim de Boer Time and Matter, Venice, March 2013 Status of Higgs Hunt in July 2012

14. 14 Wim de Boer Time and Matter, Venice, March 2013 pp processes in Standard Model 7 14 TeV 9 orders of magnitude: 1 in a billion Higgs events are rare ! Need  5x more lumi at 14 TeV to discover 500 GeV Higgs

15. 15 Wim de Boer Time and Matter, Venice, March 2013 SM background well understood

16. 16 Wim de Boer Time and Matter, Venice, March 2013 Higgs Production at the LHC „gluon fusion“ „vector boson fusion“ „vector boson radiation“ „tt associated produktion“ Rate @ 8 TeV 25-50% higher than7 TeV

17. 17 Wim de Boer Time and Matter, Venice, March 2013 Higgs branching ratios Note that q,l width ~ M while W,Z width ~ M 3. Hence bb dominates below WW “threshold”.  is down by ~ 9 due to coupling to mass, and 1/3 color factor.

18. 18 Wim de Boer Time and Matter, Venice, March 2013 Higgs branching ratios  bb dominates below WW threshold.   is down by ~ 9 due to coupling to mass, and 1/3 color factor.  WW higher than ZZ because distinguisable particles:  In addition phase space. We are lucky with Mh=126 GeV: bb down to 60 % and „golden“ channels ZZ->4l and  already appreciable! (golden, since they show narrow invariant mass peak with width limited by experimental resolution)

19. 19 Wim de Boer Time and Matter, Venice, March 2013 Searching for the Higgs in the four leptons final state For a low mass Higgs the fourth lepton is soft. Selection cuts: Electrons p T > 7 GeV Muons p T > 5 GeV 40 GeV < m 12 < 120 GeV m 34 > 12 GeV

20. 20 Wim de Boer Time and Matter, Venice, March 2013 Higgs candidate ZZ event (8TeV) with 2 µ and 2 e

21. 21 Wim de Boer Time and Matter, Venice, March 2013 H  ZZ  4 leptons Expected: BG:9.4, SIGNAL: 18.6 Total: 28 Observed: 25 Signal strength:  0.9  0.3 Significance 6.7  exp) Mass: 125.8 ± 0.5 (stat) ± 0.2 (syst) GeV 66 77

22. 22 Wim de Boer Time and Matter, Venice, March 2013 December 2012 data Significance 4.5  Mass 126.2 ± 0.6 (stat) ± 0.2 (syst) GeV

23. 23 Wim de Boer Time and Matter, Venice, March 2013 Search for the SM Higgs boson in the  channel  m /m = 0.5 [  E1 /E 1   E2 /E 2  cot(  /2)  ] H   Simulation (100 fb -1 ) PbWO4 crystals Test Beam October 2003 Target for the intercalibration < 0.5% Mass resolution is the key for Higgs discovery in this channel

24. 24 Wim de Boer Time and Matter, Venice, March 2013 Mass resolution of  system: Find the right vertex Algorithm to find the right vertex based on  p T 2 of tracks and p T  balance. Tested on Z  events by treating muons as gammas. Overall efficiency to find the right vertex for Higgs (m = 120 GeV) integrated over p T spectrum: ~ 80%    m /m = 0.5 [  E1 /E 1   E2 /E 2  cot(  /2)  ] Need vertex to better than 10 mm, bunch 50 mm

25. 25 Wim de Boer Time and Matter, Venice, March 2013 Diphoton Candidate

26. 26 Wim de Boer Time and Matter, Venice, March 2013  Mass Distribution Background is estimated from the data by a polynomial fit. An excess is observed consistent with a narrow resonance around 125 GeV mass at 4.1 

27. 27 Wim de Boer Time and Matter, Venice, March 2013 Outline  Evidence for a Higgs particle in CMS  Is it Peter´s Higgs or just a Higgs?  What it has to do with the “origin of mass” in the universe?  What is the Higgs boson good for?  What is so special about observed Higgs particle?

28. 28 Wim de Boer Time and Matter, Venice, March 2013 Other Channels Search for the Higgs in other decay modes : WW, bb and  Combined significance at M H =125.8 GeV: 6.9  Overall satisfactory level of compatibility with the SM cross section. Combined  /  SM = 0.88 ± 0.21 (so signal consistent with Peter’s Higgs) MH=125.8 GeV Expected (  ) Observed (  ) ZZ5.04.5  2.84.1 WW4.33.0 bb2.21.8  2.51.5 Combination7.86.9

29. 29 Wim de Boer Time and Matter, Venice, March 2013 A first glimpse at Spin Parity in favour of 0 + ! p(0 – ) = 0.072 p(0 + ) = 0.72 So spin and parity consistent with Peter’s Higgs  Spin 0  2 S=1 particles  angular correlations.  Positive parity   1  2 allowed  decay planes aligned.  Negative parity   1  2 allowed  decay planes orthogonal

30. 30 Wim de Boer Time and Matter, Venice, March 2013 Couplings for various channels

31. 31 Wim de Boer Time and Matter, Venice, March 2013 Fit of generalized couplings So couplings consistent with Peter’s Higgs

32. 32 Wim de Boer Time and Matter, Venice, March 2013 Outline  Evidence for a Higgs particle in CMS  Is it Peter´s Higgs or just a Higgs?  What it has to do with the “origin of mass” in the universe?  What is the Higgs boson good for?  What is so special about observed Higgs particle?

33. 33 Wim de Boer Time and Matter, Venice, March 2013 Is Higgs Field the „Origin of Mass“? Answer: Yes and No. Energy or mass in Universe has little to do with Higgs field. Higgs field gives only elementary particles mass. Mass in universe: 1)Atoms: most of mass from binding energy of quarks in nuclei, provided by energy in colour field, not Higgs field. (binding energy  potential energy of quarks  kinetic energie of quarks, ca. 1 GeV, mass of u,d quarks below 1 MeV!) 2) Mass of dark matter: unknown, but in Supersymmetry by breaking of this symmetry, not by breaking of electroweak symmetry. 3)Dark energy: Higgs energy density seems too large. Why? Gigantic problem!  matter = 0.3  dark energy = 0.7

34. 34 Wim de Boer Time and Matter, Venice, March 2013 The gigantic dark energy problem Accelerated expansion of universe implies a constant energy density in space time, either a cosmological constant or some kind of vacuum energy. The Higgs field is thought of as permeating space time with a constant energy density, which can be easily estimated from the effective potential to be 55 orders of magnitude above the dark energy density of about 10 -29 g/cm 3 If zero-point fluctuations of field considered and integrated to Planck scale, problem even more severe: (10 18 ) 4 GeV 4 = 120 orders of magnitude larger than the dark energy density In Supersymmetry problem somewhat less, since above breaking scale fermions and bosons cancel in zero-point fluctuations, problem „only“ 60 orders of magnitude. V(  =  0 ) = -m H 2 m W 2 /2g 2 = O(10 8 GeV 4 ) = 10 26 g/cm 3 1 GeV 4 =(GeV/c 2 )(GeV 3 /(ħc) 3 ) = 10 -24 g 10 42 cm -3 = 10 18 g/cm 3 Average density in universe:  crit = 2.10 -29 g/cm 3 WHY IS THE UNIVERSE SO EMPTY???

35. 35 Wim de Boer Time and Matter, Venice, March 2013 Outline Evidence for a Higgs particle in CMS Is it Peter´s Higgs or just a Higgs? What it has to do with the “origin of mass” in the universe? What is the Higgs boson good for? What is so special about observed Higgs particle? Does the observation point to physics beyond the Standard Model?

36. 36 Wim de Boer Time and Matter, Venice, March 2013 What is the Higgs boson good for? Answer: without Higgs field we would not exist! E.g. It gives mass to the electron: without electron mass no atoms (r  1/m e ) It gives mass to the W,Z bosons, which make weak interactions weak at low energy, so the sun shines for 8 billion years

37. 37 Wim de Boer Time and Matter, Venice, March 2013 Outline Evidence for a Higgs particle in CMS Is it Peter´s Higgs or just a Higgs? What it has to do with the “origin of mass” in the universe? What is the Higgs boson good for? What is so special about the observed Higgs particle?

38. 38 Wim de Boer Time and Matter, Venice, March 2013 What is so special about the Higgs boson? Higgs mass below 130 GeV, as PREDICTED by SUSY! W. Hollik: for me the observed Higgs boson with a mass consistent with Supersymmetry is the strongest hint for Supersymmetry! H (SM, 1 doublet) h,H,A,H +,H - (MSSM, 2 doublets) h1,h2,h3,a1,a2,H +,H - ( NMSSM, 2 doublets, 1 singlet)

39. 39 Wim de Boer Time and Matter, Venice, March 2013 Other beautiful SUSY features  SUSY provides UNIFICATION of gauge couplings  SUSY provides UNIFICATION of Yukawa couplings  SUSY has no quadratic divergencies  Higgs mass can be calculated up to unification scale  SUSY predicts EWSB with lightest Higgs below 130 GeV LHC: Mh = 126 GeV  SUSY provides „dark matter miracles“: Neutralino annihilation x-section a few pb  correct relic density Neutralino-nucleon scattering cross section < 10 -8 pb  consistent with experimental limits

40. 40 Wim de Boer Time and Matter, Venice, March 2013 Unification for TeV SUSY masses U. Amaldi, WdB, H. Fürstenau, PLB, 1991, wdb. C, Sander, PLB 2004, hep-ph/0307049  i are gauge couplings of SU(3)  SU(2) L  U(1) (in first order  i  1/log (energy Q)

41. 41 Wim de Boer Time and Matter, Venice, March 2013 Common masses at GUT scale: m 0 for scalars m 1/2 for S=1/2 gauginos m 1,m 2 for Higgs bosons m 2 driven negative by top loops , electroweak symmetry breaking at M Z for 140<M t <200 GeV! BINGO, Mtop predicted in this range by SUSY and it was found at 171 ± 1.3 GeV! Higgs mechanismus predicted in SUSY EWSB only works if starting point at GUT scale not too large: need   EW scale, but it is term of supersymm. potential, could be GUT scale (  -problem)

42. 42 Wim de Boer Time and Matter, Venice, March 2013 is  term of MSSM. If  is vev from singlet S, no problem to be small. Now 3 scalar Higgs bosons! (and 2 pseudoscalar) NMSSM solves  -problem MSSM NMSSM

43. 43 Wim de Boer Time and Matter, Venice, March 2013 Higgs mass in MSSM and NMSSM MSSM Higgs mass in MSSM  125 GeV for mstop  3 TeV NMSSM: mixing with singlet increases Higgs mass at BORN level for small tan  and large NO MULTI-TEV stops needed

44. 44 Wim de Boer Time and Matter, Venice, March 2013 Branching ratios in NMSSM may differ from SM  Total width of 126 GeV Higgs  tot may be reduced somewhat by mixing with singlet (singlet component does not couple to SM particles).  Then branching ratios enhanced, e.g. BR(H  tot enhanced (enhancement may be reduced by light stops at gluon fusion loop by neg. interference with top loops)  Main decay mode BR(H  bbar  bbar  tot hardly effected, as long as  bbar    tot  Higgs with largest singlet component usually lightest one. Since it has small couplings to SM particles, it is NOT excluded by LEP limit.

45. 45 Wim de Boer Time and Matter, Venice, March 2013 Many papers on NMSSM after Mh=126 GeV and hint of too high Br into , see arXiv:1301.6437, arXiv:1301.1325, arXiv:1301.0453, arXiv:1212.5243, arXiv:1211.5074, arXiv:1211.1693, arXiv:1211.0875, arXiv:1209.5984, arXiv:1209.2115, arXiv:1208.2555, arXiv:1207.1545, arXiv:1206.6806, arXiv:1206.1470, arXiv:1205.2486, arXiv:1205.1683, arXiv:1203.5048, arXiv:1203.3446, arXiv:1202.5821, arXiv:1201.2671, arXiv:1201.0982, arXiv:1112.3548, arXiv:1111.4952, arXiv:1109.1735, arXiv:1108.0595, arXiv:1106.1599, arXiv:1105.4191, arXiv:1104.1754, arXiv:1101.1137, arXiv:1012.4490, ……….. Status of NMSSM NMSSM consistent with h1=95 GeV, h2=126 GeV, motivated by 2  excess observed at LEP at 95 GeV with signal strength  2 well below SM. Hard to discover at LHC, may be in decay mode h3  h2+h1

46. 46 Wim de Boer Time and Matter, Venice, March 2013 Determining allowed SUSY parameter range Variables calculated with NMSSMTools 3.2.4 using Ulrich Ellwanger*, John F. Gunion**, Cyril Hugonie*** http://www.th.u-psud.fr/NMHDECAY/nmssmtools.html MicrOMEGAs 2.4.1 G. Bélanger, F. Boudjema, P. Brun, A. Pukhov, S. Rosier-Lees, P. Salati, A. Semenov http://lapth.in2p3.fr/micromegas/ Minuit for minimization  LHC limits on squarks and gluinos.  Mh=126 GeV These dominate parameter space

47. 47 Wim de Boer Time and Matter, Venice, March 2013 Allowed parameter space LHC Xenon  +M A B s  LEP

48. 48 Wim de Boer Time and Matter, Venice, March 2013 LHC exclusion at 7 and 14 TeV

49. 49 Wim de Boer Time and Matter, Venice, March 2013 Expected Higgs masses in NMSSM

50. 50 Wim de Boer Time and Matter, Venice, March 2013 Expected Higgs decays in NMSSM

51. 51 Wim de Boer Time and Matter, Venice, March 2013 Expected Higgs x-sections in NMSSM

52. 52 Wim de Boer Time and Matter, Venice, March 2013 Expected coupling precision (SM)

53. 53 Wim de Boer Time and Matter, Venice, March 2013 Summary  Higgs boson at 126 GeV well established  All properties (Br and Spin) consistent with SM Higgs boson  Higgs hunt not over, since mass in range expected from Supersymmetry, which predicts more Higgs bosons  Hopefully a Higgs comes seldom alone  Need Br at level of a few % to check possible deviations expected in NMSSM

54. 54 Wim de Boer Time and Matter, Venice, March 2013 From Concept to Data Taking: 18 years CMS cut in mid-plane Letter of Intent (1992) Technical Proposal (1995) 10 Technical Design Reports (1997-2006) 3000 scientists from 40 countries Silicon Tracker Hermetic electromagnetic calorimeter Scintillating Crystals Hermetic electromagnetic calorimeter Scintillating Crystals Hermetic Hadron Calori- meter: Brass scintillator Muon Chambers

55. 55 Wim de Boer Time and Matter, Venice, March 2013

56. 56 Wim de Boer Time and Matter, Venice, March 2013

57. 57 Wim de Boer Time and Matter, Venice, March 2013

58. 58 Wim de Boer Time and Matter, Venice, March 2013

59. 59 Wim de Boer Time and Matter, Venice, March 2013

60. 60 Wim de Boer Time and Matter, Venice, March 2013

61. 61 Wim de Boer Time and Matter, Venice, March 2013