MASSIVE THOUGHTS

Young-Kee KimUniversity of California, Berkeley

(CDF Experiment at Tevatron)

University of ChicagoFebruary 8, 2002

OUTLINE

Mechanism of giving masses to particles the Higgs Boson

Indirect Probe of the Higgs Boson Precision Meas.: MZ,sin2W, MW, Mtop

Direct Searches for the Higgs current & future

The Standard Theory of Particle Physicsin the basic form

A Symmetric System of EquationsA Symmetric World

GeV = 109 eV ~ Mpc2

Mass(GeV)

Leptons Quarksmatter particles : spin ½ fermions

force carriers : spin 1 bosons

Elementary particle masses in the real worldAsymmetric World

Leptons Quarksmatter particles : spin ½ fermions

force carriers : spin 1 bosons

Mass(GeV)

three most massive particles

d

s

cb

Mass(GeV)

Particles Decay via Weak Interactions.

t

e

u

n (d)

p (u)

e-

e

W-

e

t

b

e+

e

W+

e+

e

W+

g

GF

Add a field into our Symmetric Equations

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 “Higgs” fields (neutral, spin 0) withnon-zero vacuum expectation value <>0 into out equations.

Physical vacuum is filled with Higgs particles, quanta of Higgs fields.(Higgs particles condensed)

Spontaneous Electroweak Symmetry Breaking

0 0 <>0

Me= ge <>o : ge ~ 10-6

Mt= gt <>o : gt ~ 1

g = e/sinW, <>o-2 = 23/2 GF, MW = 37.3 GeV / sinW

Higgs Mass : No specific predictionSome consistency conditions restrict

MH < 1,000 GeV = 1 TeV

eW

g

B

W3

AZ

W

EW

xxx

xx

x

x

xe

t

x

xx

x

xx

xx

xx

MZ = MW/cosW

M = 0

W

Z

MW= g <>o

Higgs Particles Condensed

g

ge

gt

OUTLINE

Mechanism of giving masses to particles the Higgs Boson

Indirect Probe of the Higgs Boson Precision Meas.: MZ,sin2W, MW, Mtop

Direct Searches for the Higgs current & future

EW observables probe the Higgs bosons indirectlyby means of quantum corrections.

Large quantum corrections to EW observables come fromthe top quark.

Electroweak Measurements

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 EWMeasurements

Inputs : GF

em(MZ2)

MZ

Mtdirect = 174.3 +- 5.1 GeVMt

indirect = 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)

900 GeV p on 900 GeV p

LEP (Z, W)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+

tt production

Main Injector(new)

Tevatron

DØCDF

Chicago

p source

Booster

Wrigley Field

e-

u

db

b

Acceleration 900 GeV p on 900 GeV p

Accelerators (Colliders)

LEPSLC

100 GeV

1000 GeV

E (Ebeam / M) 4

W, Z, Top eventsContain e, , , b, …

Detectorcross-section

b’s are detected by a silicon device.

’s will escape, carrying away momentum.B

~5mm

Detection Tevatron:tt/inelastic ~ 10-10

CDF Detector

tt candidate (CDF)

e-

u

db

b

-

OUTLINE

Mechanism of giving masses to particles the Higgs Boson

Indirect Probe of the Higgs Boson Precision Meas.: MZ,sin2W, MW, Mtop

Direct Searches for the Higgs current & future

Future Precision Measurements

Precision Measurement of MZ

(pb)

e+e- cm energy (GeV)

12(s- MZ

2)2 + s2Z2/MZ

2MZ2

s Z2ee ff

Z2

e+

e-

f

Zf

e+

e-

f

f

ff = + /Z +

ff ~ +

2sinW

LEP 1,2

Precision Meas.s of MZ & sin2W

Mz (LEP1) = 91.1871 +- 0.0021 GeV~ 2 x 10-5

sin2eff (LEP1 + SLC) = 0.23156 +- 0.00017~ 7 x 10-4

e+

e-

f

Z Zf

LEP 2 (e+e-) Tevatron (pp)

W-

W+ W+

due-e+

pp

W+ e+W- ud W+ e+

i=1

2

3

MW = 2PeP(1–cos3D) MTW = 2PT

ePT(1–cos2D)

Precision Measurement of MW

Pi(W+) + Pi(W-) = 0, i=1,2,3 Pi(W+) = 0, i=1,2

E(W+) + E(W-) = E(e+) + E(e-)

Precision Measurement of MW

LEP 2 (e+e-) Tevatron (pp)

Mw(CDF+D0) = 80.452 +- 0.062 GeV

Mw(ALEPH+DELPHI+L3+OPAL)= 80.442 +- 0.040 GeV

DataSimulation

W e

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), …

Mtop(CDF+D0) = 174.3 +- 5.1 GeV

tt production

e-

u

db

b

Measurement of Mtop at Tevatron

MH < 165 ~ 206 GeV at 95% CLFavor light Higgs

Precision EW Measurements

Mw(GeV)

MH(GeV)

Mtop (GeV) year

1 prediction

1991 Mtop limit

1991

2001

1995

EW Measurements (last ~10 years)

OUTLINE

Mechanism of giving masses to particles the Higgs Boson

Indirect Probe of the Higgs Boson Precision Meas.: MZ,sin2W, MW, Mtop

Direct Searches for the Higgs current & future

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

Light Higgs Searches

H

e+

e-

H

u

u

He+

e- b

b

ge

gu

u b

b

gu

Higgs Searches at LEP 2 (e+e- collider)

e+e- ZHcross section (fb)

e+e- cm energy (GeV)

M > 109 GeV3.0 ZH, 3.6 bgrn, 6 observed

~2 excess observed in agreement with MH ~ 115 GeV

or MH > 113 GeV at 95% CL

ZH Candidates at LEP 2

e+e-bb bb ee++ee--bb bb

L3L3ALEPHALEPH

& girls

TevatronLEP 2

Higgs Searches : LEP 2 Tevatron

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

CDF DØMain Injector

(new)

Tevatron

DØCDF

Chicago

p source

Booster

Wrigley Field

Tevatron & CDF/D0 Upgrade (Run II)

Run IIa

Tevatron Run IIa EW Measurements

Tevatron & CDF/D0 Upgrade (Run II)

HW+

W-Hd-

u

W+*

W+

LEPReach

t

Run IIa2001 ~ 2003 : 2fb-1

Run IIb2004 ~ 2007 (?)

20fb-1 (?)

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 3 coverage over most of mass range, MH < 180 GeV.

** Well motivated extensions of the SM predict MH < 130 ~ 150 GeV.

Tevatron Higgs Discovery Potential

installing silicon tracker, prior to detector roll-in

CDF Detector

electronics

1.5m

~722 k channels

silicon

CDF Silicon System

residual dist. (cm)

Hit Resolution~200 m

Goal : 180 m

96 layers

e+

e-

CDF Drift Chamber

a collaboration of several groups includingY.K.Kim’s group (Berkeley)

Z +-

Muonsystems

Z e+e-

CDF Z event candidates

Calorimetery

Muon system

Ko p B+ J/ K+

Z e+ e- Jets

J/ +-

() GeV/c2

W e transverse mass

CDF : Preparing for First Physics …

CDF Triggers

Physics with 200 pb-1

B physics BS mixing sin2

Top, EWK physics a larger sample

~ (Run I) x 4

Extend SUSY and new particle studies

QCD

BS DS , DS DS

SM

discovery

hint

CDF Near-term Prospects

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

Physics beyond the Standard Model

Evolution of EM, Weak, Strong

SM

SUSY

~~

e+ e-

superparticle

e e~

e

Me Me

necessary to understand EWSB

1991 2021 (year)

LEP (e+e-) 208 GeV

LHC (pp) 14 TeV

Tevatron (pp) 2 TeVRun IIRun I

Energy Frontier Acceleratorsto understand origin of Mass

2001 2011

e+e-(0.5-1 TeV) ?

e+e-, +- (2-4 TeV) ?pp (~100 TeV) ?

Conclusions Origin of mass Higgs

Indirect probe from MW, sin2w, MZ, MTOP.

The Higgs boson is around the corner !

Possible senarios in this decade1. Discover Higgs : MH < 130 GeV

The Standard Model or New Physics ?2. Discover Higgs : MH > 130 GeV

Rules out some extensions of the Standard ModelDoes it agree with Electroweak measurements ?

3. No discovery upto LHC : MH > ~800 GeV

Detectable effects appear in W boson pairs at ~1 TeV.

Whatever the outcome, It will be extremely interesting. At present, it is essentially an experimental question.

spin ½ fermions spin 1 bosons

Higgs : spin 0 boson