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MASSIVE THOUGHTS Young-Kee Kim University of California, Berkeley (CDF Experiment at Tevatron) University of Chicago February 8, 2002. OUTLINE. Mechanism of giving masses to particles  the Higgs Boson Indirect Probe of the Higgs Boson  Precision Meas.: M Z ,sin 2 q W , M W , M top

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MASSIVE THOUGHTS Young-Kee Kim University of California, Berkeley (CDF Experiment at Tevatron)


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    1. MASSIVE THOUGHTS Young-Kee Kim University of California, Berkeley (CDF Experiment at Tevatron) University of Chicago February 8, 2002

    2. OUTLINE • Mechanism of giving masses to particles  the Higgs Boson • Indirect Probe of the Higgs Boson  Precision Meas.: MZ,sin2qW, MW, Mtop • Direct Searches for the Higgs  current & future

    3. The Standard Theory of Particle Physics in the basic form A Symmetric System of Equations A Symmetric World GeV = 109 eV ~ Mpc2 Mass (GeV) force carriers : spin 1 bosons Leptons Quarks matter particles : spin ½ fermions

    4. Elementary particle masses in the real world Asymmetric World Mass (GeV) Leptons Quarks matter particles : spin ½ fermions force carriers : spin 1 bosons

    5. three most massive particles

    6. Particles Decay via Weak Interactions. nm b m+ t e+ e+ ne ne p (u) n (d) e- ne t b t c Mass (GeV) s m d W+ u e ne nm nt g W+ W-

    7. GF

    8. Sym. System of Eq.s Sym. Solution – Unstable Asym. Solution – Stable Asymmetric World  Spontaneous Sym. Breaking Sym. System of Eq.s Sym. Solution – Stable Symmetric World Add a field into our Symmetric Equations <f>0 0 0 • Add “Higgs” fields (neutral, spin 0) with non-zero vacuum expectation value <f>0 into out equations. • Physical vacuum is filled with Higgs particles, quanta of Higgs fields. (Higgs particles condensed)  Spontaneous Electroweak Symmetry Breaking

    9. n W g e W3 Z A qW B EW e x x x x t x x x x Higgs Particles Condensed g Mg = 0 g x x x MW= g <f>o W x x x x x Z MZ = MW/cosqW x x g = e/sinqW, <f>o-2 = 23/2 GF, MW = 37.3 GeV / sinqW Me= ge <f>o : ge ~ 10-6 ge Mt= gt <f>o : gt ~ 1 gt Higgs Mass : No specific prediction Some consistency conditions restrict MH < 1,000 GeV = 1 TeV

    10. OUTLINE • Mechanism of giving masses to particles  the Higgs Boson • Indirect Probe of the Higgs Boson  Precision Meas.: MZ,sin2qW, MW, Mtop • Direct Searches for the Higgs  current & future

    11. Electroweak Measurements • EW observables probe the Higgs bosons indirectly by means of quantum corrections. • Large quantum corrections to EW observables come from the top quark.

    12. Mtop : Direct vs. Indirect Indirect meas.s : fits to EW observables Direct meas.s : CDF and D0 Lower limits : direct searches in e+e- and pp

    13. Precision EW Measurements Inputs : GF aem(MZ2) MZ

    14. Mtdirect = 174.3 +- 5.1 GeV Mtindirect = 169 +10-8 GeV Mwdirect = 80.448 +- 0.034 GeV Mwindirect = 80.374 +- 0.034 GeV

    15. You should go to the masses, learn from them, and synthesize their experience into better, articulated principles and methods, …… - Mao -

    16. Energy Frontier Accelerators Tevatron (W, Top) LEP (Z, W) 900 GeV p on 900 GeV p 1 : 45 GeV e- on 45 GeV e+ 2 : 80~103 GeV e- on 80~103 GeV e+ SLC (Z) 45 GeV e- on 45 GeV e+

    17. 900 GeV p on 900 GeV p Chicago  Booster CDF DØ Tevatron p source Main Injector (new) Acceleration tt production u Wrigley Field b d e- b n

    18. Accelerators (Colliders) 100 GeV 1000 GeV SLC LEP Eg (Ebeam / M) 4

    19. Detection Tevatron: stt/sinelastic ~ 10-10 W, Z, Top events Contain e, m, n, b, … Detector cross-section n’s will escape, carrying away momentum. B b’s are detected by a silicon device. ~5mm

    20. CDF Detector

    21. - tt candidate (CDF) u b d e- b n

    22. OUTLINE • Mechanism of giving masses to particles  the Higgs Boson • Indirect Probe of the Higgs Boson  Precision Meas.: MZ,sin2qW, MW, Mtop • Direct Searches for the Higgs  current & future • Future Precision Measurements

    23. Precision Measurement of MZ LEP 1,2 s(pb) e+e- cm energy (GeV) 2 e+ e+ f f sff ~ sinqW + g Z e- f e- f Gee Gff s GZ2 12p sff = sg + sg/Z + MZ2 GZ2 (s- MZ2)2 + s2GZ2/MZ2

    24. Precision Meas.s of MZ & sin2qW Mz (LEP1) = 91.1871 +- 0.0021 GeV ~ 2 x 10-5 sin2qeff (LEP1 + SLC) = 0.23156 +- 0.00017 ~ 7 x 10-4 e+ f Z Z e- f

    25. Precision Measurement of MW LEP 2 (e+e-) Tevatron (pp) W- e+ e- u d W+ W+ p p W+ e+n, W- ud W+ e+n 3 Pi(W+) + Pi(W-) = 0, i=1,2,3 Pi(W+) = 0, i=1,2 2 i=1 E(W+) + E(W-) = E(e+) + E(e-) MW = 2PePn(1–cosq3D) MTW = 2PTePTn(1–cosq2D)

    26. Precision Measurement of MW Data Simulation LEP 2 (e+e-) Tevatron (pp) CDF: Ia(’92-’93) D.Saltzberg + H.Frisch (U.Chicago), R.Keup (UI), Y.K.Kim (Berkeley), … Ib(’94-’95) A.Gordon (Harvard), M.Lancaster + Y.K.Kim (Berkeley), … W  en Mw(ALEPH+DELPHI+L3+OPAL) = 80.442 +- 0.040 GeV Mw(CDF+D0) = 80.452 +- 0.062 GeV

    27. Measurement of Mtop at Tevatron tt production u b d e- b n Mtop(CDF+D0) = 174.3 +- 5.1 GeV

    28. Precision EW Measurements MH < 165 ~ 206 GeV at 95% CL Favor light Higgs

    29. EW Measurements (last ~10 years) 1991 Mtop limit Mw (GeV) MH (GeV) 2001 1991 1995 1s prediction year Mtop (GeV)

    30. OUTLINE • Mechanism of giving masses to particles  the Higgs Boson • Indirect Probe of the Higgs Boson  Precision Meas.: MZ,sin2qW, MW, Mtop • Direct Searches for the Higgs  current & future

    31. Light Higgs Searches u e- • If light Higgs exists • Tevatron (1800 GeV pp collider) LEP 2 (200 GeV e+e-) produce them. • Hard to observe • Higgs coupling to stable matter very small. • Low production rate • H  bb swamped by other processes. • Poor signal / background • Strategies • e+e- Z*  Z H • u d  W+*  W+ H (MH < 135 GeV) u u  H  W+W- (MH > 135 GeV) • Low production rate, Clean signature H H u e+ e- b ge H e+ b u b gu g u b

    32. Higgs Searches at LEP 2 (e+e- collider) M > 109 GeV 3.0 ZH, 3.6 bgrn, 6 observed e+e- ZH cross section (fb) e+e- cm energy (GeV) ~2s excess observed in agreement with MH ~ 115 GeV or MH > 113 GeV at 95% CL

    33. ZH Candidates at LEP 2 e+e-bb bb e+e-bb nn ALEPH L3

    34. Higgs Searches : LEP 2  Tevatron & girls LEP 2 Tevatron

    35. Tevatron & CDF/D0 Upgrade (Run II) Chicago  Booster CDF DØ Tevatron p source Main Injector (new) 1992-96 Run I : 0.1fb-1, 1.8TeV 1996-2001 : Major detector upgrades 2001-03 Run IIa : 2 fb-1, 1.96 TeV Short shutdown to install new silicon 2004-07(?) Run IIb : ~ 15 fb-1 Wrigley Field CDF DØ

    36. Tevatron Run IIa EW Measurements Run IIa

    37. Tevatron & CDF/D0 Upgrade (Run II) u W+ W+* - d H W+ H t W- LEP Reach

    38. Run IIb 2004 ~ 2007 (?) 20fb-1 (?) Run IIa 2001 ~ 2003 : 2fb-1

    39. Tevatron Higgs Discovery Potential • By the end of Run IIa (2003 ?) ~2fb-1 we are at limit set by LEP 2 and should have a small number of WH or ZH candidates if MH ~ 115 GeV. • By the end of Run IIb (2007 ?) ~15 fb-1 we should have 3s coverage over most of mass range, MH < 180 GeV. ** Well motivated extensions of the SM predict MH < 130 ~ 150 GeV.

    40. CDF Detector installing silicon tracker, prior to detector roll-in

    41. CDF Silicon System 1.5m ~722 k channels electronics silicon

    42. CDF Drift Chamber Hit Resolution ~200mm Goal : 180mm 96 layers residual dist. (cm) e+ g e- a collaboration of several groups including Y.K.Kim’s group (Berkeley)

    43. CDF Z event candidates Z  e+e- Calorimetery Muon systems Muon system Z m+m-

    44. CDF : Preparing for First Physics … J/ym + m- M(m m) GeV/c2 Kop+ p- L  p p B+ J/y K+ Z  e+ e- W  e n transverse mass Jets

    45. CDF Triggers

    46. CDF Near-term Prospects Physics with 200 pb-1 • B physics • BS mixing • Dsin2b • Top, EWK physics • a larger sample ~ (Run I) x 4 • Extend SUSY and new particle studies • QCD BS DSp, DSppp DS  fp discovery hint SM

    47. Physics beyond the Standard Model e superparticle ~ e+ e- e e Me Me ~ ~ Evolution of aEM, aWeak, aStrong • the Standard Model • Its foundation is symmetry. • Effective Theory • Supersymmetric extensions of the Standard Model • Supersymmetry relates bosons and fermions. • h, H, A, H+, H- • h SM Higgs • Mh < ~130 GeV • Grand Unified Theory • Unification of coupling strengths SUSY SM

    48. Energy Frontier Accelerators to understand origin of Mass necessary to understand EWSB 1991 2021 (year) 2001 2011 LEP (e e ) 208 GeV + - Tevatron (pp) 2 TeV Run I Run II LHC (pp) 14 TeV e e + - (0.5-1 TeV) ? , m+m- (2-4 TeV) ? e e + - pp (~100 TeV) ?