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