View
1
Download
0
Category
Preview:
Citation preview
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The high energy physics program at theNation’s Premier platform for
DISCOVERY
Millennial Physics atFermilab
• Introduction• Standard Model• Fermilab and detectors• Remembrance of Things Past
emphasis on top• The future
Raymond BrockDepartment of Physics and Astronomy
Michigan State Universitybrock@chip.pa.msu.edu
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
what is it?
Fermilab is many things…
First, a dedicated scientific community
made up of:
– 1200 physicists, engineers, and staff
– 1000 faculty, post docs, and students from > 80 US &20 foreign institutions
plus a wonderful scientific instrument
consisting of:
– a time machine
– A particle accelerator for antirotating beams of protonsand antiprotons
– hand-made vehicles to explore the current and the veryearly universe
– A source of high energy/intensity beams of kaons andneutrinos
Officially, a single-purpose DOE national lab
located at:
– real space: 60 mi west of Chicago– cyberspace: www.fnal.gov
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Standard Model–what we know
Quarks (spin 1/2, charge 2/3 and -1/3)
Leptons (spin 1/2, charge 1 and 0)
Gauge bosons (spin 1, charge 1 and 0)
Higgs (spin 0, charge 0)
ud
cs
tb
left-handed:
right-handed: u, d, c, s, t, b
weak, strong, andelectromagnetic interactions
electromagnetic and stronginteractions
eνe
µνµ
τντ
left-handed:
right-handed: e, µ, τ
weak and electromagneticinteractions
electromagnetic interactions
g,γ,
W±,Z 0
strong,
H 0Fills the vacuum and isresponsible for mass?
electromagnetic
electromagnetic & weak
electromagnetic & weak
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
B+
B-
B0
A0
complex, spin 0
doublets
The phase transition...
H0
You are here...
γ
Z0
1015 K10-12 sec
1 K10+18 sec
θW = 28º
W±
TC
A useful way to think about things: think back…way back
Count the dof: massless, spin 1 = 2massive spin 1 = 3
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
All mixed up
Important SM relations
– Mixing characterized by an angle, θW
(“Weinberg” or “weak” angle)
–
θW can be measured many ways…in different reactions
γ = B0 cosθW + W 0 sinθW
Z = W 0 cosθW − B0 sinθW
e = gW sinθW
GF
2= gW
2
8MW
MW = 12
gW v ≅ 80 GeV / c2 ⇒ v ≅ 246 GeV
MZ = MW / cosθW ≅ 90 GeV / c2
T>Tc , a triplet of spin 1 bosons,W±0 and a singlet, A0 – T<Tc W0-A0 mix
MZ constrained byMW and θW
scale of EWSymmetry breaking
Electromagnetism mixed withweak interactions
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
First, working within a restrictive, successfulsingle model is unusual – it works too well.
Gauge symmetry – a good idea … but why:– SU(2) x U(1) hard-wired to account for known weak
and electromagnetic phenomena. Higher symmetry?
Symmetry breaking– What is the character of the breaking?
Quarks-leptons?– Pattern looks suspicious, right? Why?
– 3 sets? Z decay & astrophysics suggest “yes”
– Substructure? Stringyness?
Fermion mixing– Why is there matter and not Antimatter?
– Do neutrinos also mix, and hence have mass?
Why and how is there mass?– Thought to be induced by the Higgs field…
• Ubiquitous, fills the vacuum acting almost like aviscous medium
• The Cooper Pair of the particle ground state
Gravity
Standard Model–what we don’t know
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Masses
so, what is it with mass, anyhow?
10 100 150 2001 50
up: 0.1 GeV/c2
strange: 0.3 GeV/c2
charm: 1.5 GeV/c2
bottom: 4.5 GeV/c2
top: 175 GeV/c2
electron: 0.0005 GeV/c2
e neutrino: 0
muon: 0.1 GeV/c2
µ neutrino: 0
tau: 1.7 GeV/c2
τ neutrino: 0
gluon: 0
photon: 0
W: 80 GeV/c2
Z: 91 GeV/c2
Higgs: > ~ 86 GeV/c2 from LEP
down: 0.1 GeV/c2
250
EW symmetry breakingscale…eh? eh??
favoredLogically heavier okay
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The vertices
Feynman diagrams for vertices (fermioninteractions)
Neutral electroweak
−ie
sinθW cosθW
1
2γ µ
1 −γ 5
2
−ieQ jγµδ ij
−igW
2γ µ (1 − γ 5 )
Charged electroweak
Strong
−igS
λα
2γ µ
Higgs
−ie
2 sinθW
m f
MW
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
New physics is in the loops
IVB Propagators contain the hints
Contribution ~ m 2top / M 2W)How we knew where to look then
Contribution ~ ln(m 2Higgs / M 2W)How we know where to look, now
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
HEP around the world
7 laboratories in the world dedicated to HEP– In the US: SLAC (e+e-); CESR (e+e-); Fermilab (pp &
assorted)
– In Europe: CERN (e+e-); HERA (ep); DAΦNE(e+e-)
– In Asia: BEPC(e+e-); KEK (e+e-)
Future facilities are:– In the US: PEPII1999(e+e-); CESRII1999(e+e-); Fermilab
MI2000(pp)
– In Europe: LHC2007(pp)
– In Asia: KEKB1999(e+e-)
The U.S. will lose the lead unless we figure outhow to build a facility beyond LHC, 2010
Imagined facilities include:
– In US: NLC(e+e-); muon collider(µ+ µ -); VLHC(pp)
– In Europe: NLC(e+e-), τ charm(e+e-)
– In Asia: NLC(e+e-)
To probe the important questions we get together with400-500 of our closest friends and perform experiments
at just a few international facilities.
To probe the important questions we get together with400-500 of our closest friends and perform experiments
at just a few international facilities.
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
HEP around the world, today.
SLAC e+e-
Fermilab pp
CERN e+e-
Cornell e+e-
KEK e+e-
BEPC e+e-
DESY ep
DAΦNE e+e-
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Some jargon: pT - transverse momentum (conserved)η - pseudo rapidity [ = ln(tan(θ /2)]
σ - barn (1b = 10-28 m2)
L - instantaneous luminosity #/cm2 s, N = σ L TL - integrated luminosity, [ = ∫ L dt ]
A dictionary & the calendar
• The currency at Fermilab is L in pb-1 and fb-1
To set the scale:
σtotal(inelastic) ≈ 50 mb; σ(W eν) ≈ 2 nb; σtotal(tt) ≈ 6 pb
• The first run of the Tevatron collider with bothdetectors was:– Run I 1993-1996: 100 pb-1
• 3 periods, 1a, 1b, and 1c• Center of mass energy: 1.8 TeV (plus 630 GeV)
• The next running will start soon – and go a while– Run II 2000-2003? 1-3 fb-1
• A few periods• Center of mass energy: 2 TeV
– Run III? 2003-2008? 30 fb-1
• many periods• Center of mass energy: 2 TeV
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Accelerator Complex - the time machine
A mixture of future technologies
Tevatron
LinacBooster
Main InjectorPbar Accumulator
(Extracted beams)
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Fermi National Accelerator Laboratory
New accelerator(s):Main Injector
Central labfacility
antiprotons protons
1 m
ile
CDFexperiment
CDFexperiment
DOexperiment
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
DO detector, Y1.999k
• magent: 2T, 60cm x 2.8msuperconducting solenoid
• tracking: ∆pT/pT ≤ 5% for
pT=10 GeV/c muons, η < ~1.8
1) Si: 4 layer barrels(dbl/sgl) & dbl-sided disks(|η | ≤ 3), 0.8M ch.
2) SciFi: 8 layers ribbondblets, 77k ch. w/VLPCreadout
3) preshower: central (η <~1.5), 6k ch./fwd, 16k ch.
• muons: forward and central
1) central: faster gas;deadtimeless; bottomscint.; φ trg scint
2) forward: timing/trk-matching pixel cntrs; 3layer prop min-drift
• trigger: significant upgrade
1) 10kHz L1; 1KHz 100µs
L2; 100ms 50 Hz L3
• all significant upgrades
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
CDF detector, Y1.999k
• tracking: significant upgrade
1) Si: 5 layer, dbl sided strips
(|η | ≤ ~2.5); ISL strips
(1 ≤ |η | ≤ 2)
2) outer: smaller, open-cell COT drift chmbr. 180µ m
3) Si vertex trigger (SVT)• calorimeter: significantupgrade, forward
1) endplug: (1.1 ≤ |η | ≤ 3.6), scint. tiles w/ WLS fiber
readout• muons: moderate upgrade
1) intermediate muon system• trigger: significant upgrade
1) 50kHz L1; 0.3KHz 20µs L2; 50 Hz L3
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Run 1 performance
Accelerator performance 900 GeV/beam was staggering
Designed for 1x10 30 s-1cm-2; actual: ≤ 1.6x1031 s-1cm-2
Designed for: ∫Ldt ~ 5pb-1 ; actual: ∫Ldt ~ 110 pb-1
900 GeV/beam; 6 bunches; 3.5 µs between bunches
1-3 int/crossing (important)
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
0.1
1
10
100
1030 1031 1032 1033 1034
Mean Interactions/crossingin
tera
cti
ons/c
rossin
g
instantaneous luminosity (per cm 2 s)
“ tev_2000 ” accelerator assumptions:—Run II: commissioning, late 1999 with physics, 2000 2002?
—2 TeV @ ≤ 2 x 1032 cm-2 s-1
—396ns - 132ns bunch spacing—2fb-1 to tape
Run III: Tev33: 2003 - ?
...LHC underway ? 2006? 7?
...something cool happens?
2 TeV @ ≤ 1033 cm-2 s-1
dynamically adjusted β * ?
~25-30% int. loss†
132ns bunch spacing30fb-1 to tape
Run 2 and beyond
1992-31994-5
load-levelingtrigger?
6 bunches
36 bunches
108 bunches
2000 ?
2001 ?
Run 1b, >2 int/crossing
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Run I physics, a (tiny) snapshot
Top quark– Discovery!– mt = 174.3 ± 3.2 (stat) ± 4.0 (sys) GeV/c 2
• Beginnings of detailed studies (cross sections,distns, BR, etc.)
W/Z bosons– MW = 80.45 ± 0.063 GeV/c 2
– V-V-V couplings studied
– W/Z + soft gluon radiation
Bottom quarks – a new field
– 100’s B J/Ψ- KS
– BC discovered
– Production σ’s & BR’s
Quantum Chromodynamics– Substructure probed, 10-18 cm
– Radiative corrections confirmed
– Colorless exchange - Pomeron
Exotic physics – searches– supersymmetry
– leptoquarks
– Higgs boson
– additional W/Z’s
unanticipatedprecision
Over 250 papers published inPRL, PR, NP
Over 250 papers published inPRL, PR, NP
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The decay of a quark, Q, with mQ > MW + mq is straightforward:
Vtb is an element of the quark mixing matrix, bounded by the requirement ofUnitarity and weak interaction phenomenology.
SO, the fraction of decay of t W b is almost 100%.SO, τ top ≈ 0.4 x 10-24 s … QCD confinement scale ≈ 1/ΛQCD ≈ few x 10-24 s
Which means…top quarks decay before they form top-mesons…barefermion… unprecedented and surely a clue to something?
Vud Vus Vub
Vcd Vcs Vcb
Vtd Vts Vtb
≈
0.9745 − 0.9760 0.217 − 0.224 0.0018 − 0.0045
0.217 − 0.224 0.9737 − 0.9753 0.036 − 0.042
0.004 − 0.013 0.035 − 0.042 0.9991 − 0.9994
The TOP quark, 1
Who ordered that? – the extraordinary massdistorts one’s normal picture of a quark...
90% qq and 10% gg for pp
Γ(Q → qW+ ) =GFmQ
3
8π 2Vtb
21−
MW2
mQ2
2
1 +2MW
2
mQ2
One power of GF
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The TOP quark, 2
Getting to the bottom of the top quark…
– The b quark lives a long time…τb ≈ 1.5 ps
Si vertex detectors are magic
Can tag the presence of b quarks
– Efficiency for 1 Si vertexing (SVX) tag is ε ~50% and
essentially p(b) independent
– Can double tag with ε > 40%
– also can detect the presence of a soft lepton (SLT) fromb c l ν
• long enough to measure• Important for top physics• now a precision industry
CDF
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The TOP quark, 3
Manifests itself three ways:
Huge backgrounds: QCD multijets w/ S/B~1/1
bqq’ bqq’ 44% “dijet”
blν blν 5% “dilepton”
blν bqq’ 30% “lepton + jets”
Charged leptonMissing energy2 jets2 b quarks
serious backgrounds: QCD Wjjbb w/ S/B~2/1, 4/1 with b tagging
But wait, there’s more:
low backgrounds: QCD Wjjbb, (fake e,missing j) w/ S/B~3-4/1
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Top, revealed
t W (eν )b
t W (qq)b
DO
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Top’s bare bottom revealed
CDF
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Top quark physics: cross section
A complicated theoretical effort for comparison– Stresses QCD understanding at a deep level
– Heavy quark QCD is tough
CDF: 7.6 pb DO: 5.9 ± 1.7 pb
+ 1.8- 1.5
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Top quark physics: mass determination
Full kinematical fitting of lepton+jets, dilepton, alljets candidates– A serious challenge for background simulation
– The QCD production of W+ multiple jets w/b’s
Very sophisticated likelihood combinations ofsamples are now done– eg., CDF combined 4 indepdendent samples for their
best result
– DO employs complicated kinematical and topologicalcuts
Channel DO DO CDF CDFsample bckgnd sample bckgnd
Di-lepton 5 1.4 ± 0.4 9 2.4 ± 0.5Lep+jets SVX 34 9.2 ± 1.5Lep+jets SLT 11 2.4 ± 0.5 40 22.6 ± 2.8Lep+jets top 19 8.7 ± 1.7All jets 41 24.8 ± 2.4 184 142 ± 12eν 4 1.2 ± 0.4
eτ, µτ 4 ≈2
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Lepton plus jets mass results
CDF
DO
Systematics (GeV/c2):Jet energy det 4.4FSR 2.2ISR 1.8Bckgnd shape 1.3btag bias 0.4pdf 0.3Total 5.3
Systematics (GeV/c2):Jet energy det 4.0Bckgnd model 2.5Signal model 1.9Fitting tech 1.5Cal noise 1.3Total 5.5
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
mt results
Top Quark Mass
mt = 174.3 ± 5.1 GeV/c 2
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
ElectroWeak Interactions
The physics of W’s, γ’s, and Z’s
σ (W,Z) & ΓW determination
– “tri-boson couplings”• Testing the gauge theory at the vertices – newphysics would reveal itself here
– Mass determination (remember the loops?)• Requires precision of ±0.06% Cross section –strong test of QCD
–Theoretical prediction: O(α 2S)
Hamberg, van Neerven, Matsuura;van Neerven & Zijlstra
Dominant uncertainties:Luminosity, ≈ 8% & Parton distribution functions, ≈ 3%
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
W mass determination
A tricky measurement
Isolated leptonMissing momentum
d) σ
dmT2 =
Vqq'2
4πGFMW
2
2
21
) s − MW
2( )2+ ΓW MW( )2
2 − mT2 ) s
1 − mT2 )
s ( )1/2
mT2(l,νl) =
r p l +
r p ν l( )2
−r p l +
r p ν l( )2
= 2ETlET
ν l 1 − cosφlν( )
Moderate hadronic recoil (~5 GeV/c)
2 body decay kinematicsdefine “transverse mass”
DO latest
MW = 80.474 ± 0.093 GeV/c2 DO = 80.433 ± 0.079 GeV/c2 CDF = 80.450 ± 0.063 GeV/c2 Tevatron
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Remember, if you don’t see anything,it’s a neutrino...
DO W eν
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
RW / Z =
σ W ⋅ BR(W → lνl )
σZ ⋅ BR(Z → ll)=
σ W ⋅ Γ(W → lνl)
σ Z ⋅ BR(Z → ll) ⋅ ΓW
The full width of the W can be measured in threeways (SM: ΓW = 2.077 ± 0.014 GeV)
– Indirectly from:
– Directly from the tail of the mT distribution:
– Simultaneously, in 2 parameter fit with MW
ΓW
ΓW = 2.130 ± 0.56 GeV DO (new)
= 2.064 ± 0.084 GeV CDF
ΓW = 2.130 ± 0.56 GeV DO
= 2.064 ± 0.084 GeV CDF
ΓW = 2.19 ± 0.19 GeV CDF
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Tri-boson couplings
The IVB can couple to one-another due to thenon-Abelian nature of the Yang-Mills prescription
Measurements characterized as parameterized deviations fromSM...an anomolous magnetic or electric momentStandard Model values: κγ, Z = 1; λγ, Z = 0; hZ,γ
1-4 = 0
hZ,γ1-4
κγ, Z , λγ, Z
CDF preliminary
DO
– 0.93 < κ γ -1 < 0.94
– 0.31 < λ γ < 0.29
DO
CDF preliminary
– 1.8 < κ γ -1 < 0.94
– 0.7 < λ γ < 0.6
DO + LEP @ 68% CL∆κ γ = 0.13 ± 0.14
λ γ = 0.6 ± 0.07
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The Standard Model Connection
• LEP2 has announced resultsfrom 183 GeV running (lastweek)
• NuTeV (ν N DIS) has
preliminary resultssin2θW, interpreted as MW
IT’S A DIFFERENTGAME NOW –THE SM HIGGSBOSON APPEARSTO BE LIGHT
IT’S A DIFFERENTGAME NOW –THE SM HIGGSBOSON APPEARSTO BE LIGHT
Run2 uncertaintiesintentionally plotted @1996 central valuesGood reminder of what 1 σmeans & reason forgrowing excitement atFermilab
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Quantum Chromodynamics
Study of strong interactions– Both basic and very complicated
phenomenology–rich field
Most basic measurement–thesearch for substructure…akinto the original discovery ofpartons at SLAC
Controversial for a while: was therean excess at high jet E T?could be evidence for substructure
False alarm? Both experimentsagree…both agree with theory. Probablya reminder of how hard it is to predict thegluon distribution in the proton
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Highest ET jet event in DO ET = 475 GeV
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
QCD
Much more…– Dijet mass spectrum - another substructure search
Excess would suggest a new length scale in 2
parton collisions
From CDF inclusive jets: Blue shows the running of the strong coupling, αS(E), with
changing scale, ET. Red, shows the lack of dependence at a fixed scale. Not absolute αS(E).
• α S running determination
CDF
at an electron collider …at a hadron collider!
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
QCD
Gluons are cheap…– Indeed, they radiate like mad from quarks and gluons
and accounting for them is complicated in processes inwhich there are two length scales
• eg, the dσ /dpT for W and Z production, or γγproduction
Must deal with ∞ series ofdivergences: ln(Q 2/p 2T)
Turn-over, theeffect of QCDradiativecorrections andinfinite gluonresummation
DO preliminary
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
B Physics – HEP with microbarns
Both experiments study B mesons
CDF’s SVX tags the detached vertices of the B’s
• Largest sample in the world.
Forward productionagrees with centralproduction
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
B ut wait, there’s more
CDF: lifetimes, eg.
CDF discovered the BC meson
M(Bc) = 6.40 ± 0.39 ± 0.13 GeV/c2
τ (Bc) = 0.46 ± 0.05 ps+0.18- 0.16
BC± J/ψ l X
bound (bc)
τ (B-) = 1.637 ± 0.058 +0.045/-0.043 ps
τ (B0) = 1.474 ± 0.039 +0.052/-0.051 ps
τ (B0s) = 1.34 + 0.23/-0.19 ± 0.05 ps
τ (Λ0b) = 1.36 ± 0.09 +0.06/-0.05 ps Λb Λc l ν
B J/ψ Κ & D l XBs J/ψ φ
• CDF observed and measured B0 - B0 oscillationparameters
Combination of 3 tagging techniques:SVX “same side” tagSLT tagJet charge tag
B J/ψ Κ0s
sin2β = 0.79+ 0.41– 0.44
Where the SM predicts 0.66 - 0.84First observation of CP in the Bsystem, confirming the largeexpected asymmetry
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
the zoo
Many extensions of the SM are imaginable– All must be dealt with systematicallyExotica including:Extra gauge bosonsLeptoquarks (bound lepton-quark states)Technicolora matter of luminosity...
Measured limits are right on schedule for 100 pb-1
1996 prediction
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Goals of Run II
Accelerator:– To deliver 10-30 x more integrated luminosity
Experiments:– To deal with it...and the required upgrades
Physics goals:
– Understand the top quark, measure δ mt ≈ 3 GeV/c2
– Determine the cross section to ± 8%
– Determine the W mass to δ MW ≈ 40 MeV/c2
– Determine the W width to few %
– Determine | Vtb | to ±10%
– Refine B physics measurements, extend rare decaysearches
– Extend the reach for compositeness to 500 GeV
– Test NNLO QCD and further study the pomeron
– Extend the search reach for Supersymmetry and exoticphenomena
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Top quark physics in the future
accepted/experiment
mode 2fb-1 10fb-1
tt produced 16,000 80,000
l + ≥ 3j / 1b tag 1,800 9,000
l + ≥ 4j / 2b tags 600 3000
l l + 2j 200 1,000
EW produced top 330 1,650
With ∫Ldt = 10 fb -1, we will:•determine mtop to 1-2 GeV/c2
•measure σ (tt) to 6%•measure BR(t → b) to 5%•probe for tt resonant states to
1 TeV/c2
•Michel analysis of top couplings•isolate EW produced top quarks and:
determine σ to 10%determine Γ(t →Wb) to 10%determine V tb to 5%search for anomalous couplingssearch for CP
•probe for rare decays to 10 -3 - 10-4
With ∫Ldt = 10 fb -1, we will:•determine mtop to 1-2 GeV/c2
•measure σ (tt) to 6%•measure BR(t → b) to 5%•probe for tt resonant states to
1 TeV/c2
•Michel analysis of top couplings•isolate EW produced top quarks and:
determine σ to 10%determine Γ(t →Wb) to 10%determine V tb to 5%search for anomalous couplingssearch for CP
•probe for rare decays to 10 -3 - 10-4
Fermilab is atop quark factory
The TOP might beSpecial…we aim tofind out.
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
IVB physics
With ∫Ldt = 10 fb -1, we will:
determine MW to ~30 MeV/c 2
– which will bound MH to 40-50% of itself– (good timing for direct searches)
measure Γ(W) to 15 MeV
refine asymmetries ( W and Z) and hence, pdf’s
limit WWV and Zγ couplings
quantify radiation zero in Wγ
search for rare W decayslimit CP violationquantify quartic gauge couplingsstudy resummation in 2 scale problems
– pT(W), pT(γγ)
With ∫Ldt = 10 fb -1, we will:
determine MW to ~30 MeV/c 2
– which will bound MH to 40-50% of itself– (good timing for direct searches)
measure Γ(W) to 15 MeV
refine asymmetries ( W and Z) and hence, pdf’s
limit WWV and Zγ couplings
quantify radiation zero in Wγ
search for rare W decayslimit CP violationquantify quartic gauge couplingsstudy resummation in 2 scale problems
– pT(W), pT(γγ) accepted/experimentchannel 2fb-1 10fb-1
W→eν 1.6M 8M
Z→ee 160k 800k
Wγ 1000 5000
Zγ 300 1500WW 100 500WZ 40 400ZZ few 30
Fermilabis a vector bosoncraft-workshop
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
QCD
With ∫Ldt = 10 fb -1, we will:Study the edge of phase space!Probe deep structure beyond 500 GeVMeasure IVB+jet production with high statisticsUnderstand multi-scale physicsUnderstand multi-gluon physicsHeavy quark production kinematics/dynamicsProbe jet structureUnderstand multi-jet kinematicsNNLO calculational comparisonUnderstand diffractive scatteringSupport all other collider analyses with crucial
background studies
Search for new phenomena!
With ∫Ldt = 10 fb -1, we will:Study the edge of phase space!Probe deep structure beyond 500 GeVMeasure IVB+jet production with high statisticsUnderstand multi-scale physicsUnderstand multi-gluon physicsHeavy quark production kinematics/dynamicsProbe jet structureUnderstand multi-jet kinematicsNNLO calculational comparisonUnderstand diffractive scatteringSupport all other collider analyses with crucial
background studies
Search for new phenomena!
Fermilab is aQCD conglomerate
Millions of events,period.
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
B physics
With ∫Ldt = 2 fb -1, we will:Measure CP violation in three modes
B0 J/ψKs
B0 ππ
B0 J/ψφ
Measure | V td | / | Vts | from BS mixing & ∆Γs
Refine rare decay searches
B µµK
B µµK*
Bd µµ
Bs µµ
Completely understand the B C system
Completely understand B s mixingSemileptonic decaysFully hadronic decays
With ∫Ldt = 2 fb -1, we will:Measure CP violation in three modes
B0 J/ψKs
B0 ππ
B0 J/ψφ
Measure | V td | / | Vts | from BS mixing & ∆Γs
Refine rare decay searches
B µµK
B µµK*
Bd µµ
Bs µµ
Completely understand the B C system
Completely understand B s mixingSemileptonic decaysFully hadronic decays
accepted/experimentchannel 2fb-1 10fb-1
B mesons 1010 5x1010
B baryons 108 5x108
Bc 109 5x109
B0 J/ψKs 15,000 75,000
Fermilab is abottom quark industry
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
There’s more
Multiple inverse fb make a qualitativedifference:
Supersymmetry
and
the Anderson-Higgs Boson
are accessible before the LHC
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Supersymmetry–in words
The SM is extraordinarily successful– nothing seems out of line…yet nobody is happy.
Digging deeper is troubling– The SM describes physics of the scale of the W/Z
masses ~ 100 GeV, or distances of ~ 10-18cm
– What about deeper scales? What are scale-milestones?
• Higgs is fat, due to radiative corrections– The “Hierarchy Problem” is due to quartic self-
interactions
H H HHThe only high energy scale is the Planck scale of 1018 GeVSo, the counter term must cancel to one part in ~ 1016
Ugly...the SM is fundamentally sick
one loop contribution to the mass
Suppose the theory has Higgs’, fermions, and additional scalars
MH2 ~ MH 0 +
λ4π 2 Λ2 +δMH
2
MH
2 ~ MH 02 +
gF2
4π 2 Λ2 + mF2( ) −
gS2
4π 2 Λ2 + mS2( ) + logs +K
Relating the regular fermions and the new scalars requires asymmetry between them so that the Λ terms cancel
SUSY provides that connection: S| F > = | B >
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
In practice, difficult
Supersymmetric partners for all particles– With a spin flip…and a cute s-prefix
• Electron (spin 1/2) becomes selectron (spin 0)• Quark (spin 1/2) becomes squark (spin 0)• Photon (spin 1) becomes photino (spin 1/2)• Gluon (spin 1) becomes gluino (spin 1/2)
– No SUSY at low energies, so supersymmetry isbroken…search for their interactions at higher energies
This is not just silly…– The Higgs mechanism is accounted for in a natural way
and the Weinberg angle is predicted
– Unification of forces appears to work
– Superstrings contain SUSY...
A bold theoretical suggestion, on par with Dirac’spositron, or Weinberg’s Z !!
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
SUSY provides a unification ofcouplings
•Unification – a goal – requires serious tinkering•Each force (electromagnetic, strong, and weak) is characterizedby a coupling, α i(q) (I = 1,2,s), for
2 EW couplings and 1 QCD coupling•Unification requires that α 1(MX) = α 2(MX) = α s(MX)
α s
α 2
α 1Modern analysessuggest α s≈ 0.13
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Seeking SUSY
SUSY is not the only solution…– composite Higgs can protect itself from infinities
(technicolor)
However, it is taken very, very seriously– Many flavors of models…thousands
– A particular brand is especially promising, called theMinimal SuperSymmetric Model (MSSM) containsdefinite predictions• 4 Higgs bosons, one of which is SM-like and mustbe lighter than ≈ 125 GeV/c2
• A supersymmetric “number” is conserved, sodecays of SUSY particle result in another SUSYparticle
• A mass spectrum is conceivable, so there is asterile Lightest SUSY state…which is missingenergy in a detector
• Signals are many leptons, and/or jets withsignificant missing energy
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The time is right...
Model space
Run IIRun III
you are here
trilepton search
-ino Predicted actual
Run I 2fb-1 10fb-1 Run I
χ± 65 ~220 235 70
g 170 ~360 400 270
t1 48 150 155 145
Fermilab could be aSUSY venture startup…
Dozens of limitshave been setalready by bothexperiments
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The HIGGS is the thing...
The Higgs couples to fermions via mfBig is beautiful..
we expect a light SM Higgs to decay overwhelmingly to bpairs, or 2W’s if slightly heavier...
The GoldenMode
Remember the EW connection? The SM seems to be pointing
to a light Higgs boson
For which there is rate~
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Higgs could be ours...
Needs:– Luminosity
– Ability to tag b’s of relatively high pT
– Ability to form M(bb) with good resolution
B tagging efficiencies arealready thereWill be better in Run II
CDF
2fb-1
potentiallybetter than“nominal”
CDF: Z bb CDF MC extrapolation to Run I
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Higgs will be surrounded
M(bb) in 10 fb-1
δM ≈ 8 GeV
S/B ≈ 1/1, dependent on cutsMass resolution is key
top eventsZ bb
Run II
Run III
WH region
WW region
Recently, a year-longworkshop at Fermilab:
Fermilab could be aHiggs cottage industry
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
The plan is clear...
Run II– Provides an ability to take the top quark apart
– Uncover CP violation in the B system
– Determine the W mass to precision necessary to cornerthe Higgs
Run III, above a critical L threshold of about 20pb-1
– Will possibly discover SUSY
– Should discover the Higgs Boson• If not there, then the more promising SUSY modelis wrong, the SM EW model will be in jeopardy,
–and a whole new era in elementary particlephysics will have opened.
• If it is there, it will be studied at LHC, NLC, and/ora µ collider
–and a whole new era in elementary particlephysics will have opened.
Chip Brock, Michigan State University
physics at fermilab
April 1, 1999 Fermilab at the Millennium
Conclusion
I’ve not talked about the Kaon CP program or theneutrino oscillation program
We are guaranteed a Complete Program
programmatic, evolutionary measurements blended withsignificant discovery potential
Fermilab is the place tofollow the connections.
Taken together…This is a great time to be at Fermilab
Recommended