Chip Brock, Michigan State University physics at fermilab April 1, 1999 Fermilab at the Millennium The high energy physics program at the Nation’s Premier platform for DISCOVERY Millennial Physics at Fermilab • Introduction • Standard Model • Fermilab and detectors • Remembrance of Things Past emphasis on top • The future Raymond Brock Department of Physics and Astronomy Michigan State University [email protected]
57
Embed
Millennial Physics at Fermilab - Michigan State University · Chip Brock, Michigan State University physics at fermilab April 1, 1999 Fermilab at the Millennium Standard Model–what
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
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
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
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
– 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