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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) University of Chicago February 8, 2002
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
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
Elementary particle masses in the real world Asymmetric World Mass (GeV) Leptons Quarks matter particles : spin ½ fermions force carriers : spin 1 bosons
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-
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
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
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
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.
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
Precision EW Measurements Inputs : GF aem(MZ2) MZ
Mtdirect = 174.3 +- 5.1 GeV Mtindirect = 169 +10-8 GeV Mwdirect = 80.448 +- 0.034 GeV Mwindirect = 80.374 +- 0.034 GeV
You should go to the masses, learn from them, and synthesize their experience into better, articulated principles and methods, …… - Mao -
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+
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
Accelerators (Colliders) 100 GeV 1000 GeV SLC LEP Eg (Ebeam / M) 4
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
- tt candidate (CDF) u b d e- b n
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
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
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
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)
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
Measurement of Mtop at Tevatron tt production u b d e- b n Mtop(CDF+D0) = 174.3 +- 5.1 GeV
Precision EW Measurements MH < 165 ~ 206 GeV at 95% CL Favor light Higgs
EW Measurements (last ~10 years) 1991 Mtop limit Mw (GeV) MH (GeV) 2001 1991 1995 1s prediction year Mtop (GeV)
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
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
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
ZH Candidates at LEP 2 e+e-bb bb e+e-bb nn ALEPH L3
Higgs Searches : LEP 2 Tevatron & girls LEP 2 Tevatron
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
Tevatron Run IIa EW Measurements Run IIa
Tevatron & CDF/D0 Upgrade (Run II) u W+ W+* - d H W+ H t W- LEP Reach
Run IIb 2004 ~ 2007 (?) 20fb-1 (?) Run IIa 2001 ~ 2003 : 2fb-1
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.
CDF Detector installing silicon tracker, prior to detector roll-in
CDF Silicon System 1.5m ~722 k channels electronics silicon
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)
CDF Z event candidates Z e+e- Calorimetery Muon systems Muon system Z m+m-
CDF : Preparing for First Physics … J/ym + m- M(m m) GeV/c2 Kop+ p- L p p B+ J/y K+ Z e+ e- W e n transverse mass Jets
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
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
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) ?