A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Top Physics and
SM Higgs Searches at the Tevatron
Outline:
•The Tevatron Upgrade
•CDF and DØ Detectors
•Top Physics:
•Cross Section Production
•Top Mass
•SM Higgs searches
Antonio Sidoti
University of Pisa and INFN XV IFAE Lecce 2003
24 Aprile 2003
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
CDF DØ
Main Injector Tevatron Booster
Recycler
Fermilab Tevatron Upgrade (RunII)
Not used yet!
Lum at RunI ~110 pb -1
√ s RunI = 1.8 TeV Now √s RunII = 1.96 TeV
Higher Luminosity for RunII
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
0.00E+00 1.00E+31 2.00E+31 3.00E+31 4.00E+31 5.00E+31
04/01/01 05/01/01 06/01/01 07/01/01 08/01/01 09/01/01 10/01/01 11/01/01 12/01/01 01/01/02 02/01/02 03/01/02 04/01/02 05/01/02 06/01/02 07/01/02 08/01/02 09/01/02 10/01/02 11/01/02 12/01/02 01/01/03 02/01/03 03/01/03
Date
Peak Luminosity
0.00E+00 1.00E+31 2.00E+31 3.00E+31 4.00E+31 5.00E+31
Peak Lum 20x Average
Peak Luminosity Peak Lum 20X Average
Peak Luminosity
Winter 03 Data
RunIIa Tevatron Performances
– Base goals:
¾200 pb
-1for 2003
¾10 pb
-1/week by the end of the year
– Stretch goals:
¾320 pb
-1for 2003
¾15 pb
-1/week by the end of the year
– 2002 comparison:
¾ 80 pb
-1for the year
¾ 6.7 pb
-1best week
0.00 1000.00 2000.00 3000.00 4000.00 5000.00 6000.00 7000.00 8000.00
1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101
Week # Weekly Integrated Luminosity (nb-1)
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00
Run Integrated Luminosity (pb-1)
Weekly Integrated Luminosity Run Integrated Luminosity
Integrated Luminosity
Winter 03 Data
10
31Bunch Crossing Interval:
τ RunI = 3.5 µs
τ Run II= 396/132 ns
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
DØ RunII Detector
Many improvements from RunI:
•New solenoid installed for
•RunII (2T 60cmx2.8m ) ->New Tracking system
•Trigger + Electronics and DAQ
Si Tracker: Layers&Disks
8 Layers Fiber Tracker
Preshower
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
CDF RunII Detector
From RunI:
•Solenoid
•Muon system
•Central Calorimeter
For RunII:
•Front-end DAQ
•Trigger
Track (L1) and Displaced Track (L2)
•New Silicon Tracker (8 Layers) (|η|<2)
•Central Outer Tracker
•TOF •Plug Calorimeters
•Extended Muon Coverage (eµ) Id up to |η|~2
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
¾ Today results only RunII although integrated luminosity ~60% of RunI
¾ Re-establish Run I results
Î Proof that RunII Detectors are working well!
¾ More statistics ÖStudy Top properties with more precision (charge,BR, rare decays,...)
¾ Search for new phenomena ( e.g. single top searches, SM Higgs searches, etc…)
Top Physics at the Tevatron (backup)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Tevatron RunI Results
ttbar production cross
section M W vs M top -> Higgs Mass
Luminosity ~110 pb -1 s = 1.8 TeV
√
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Run I Top Mass (backup)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
At the Tevatron, top quarks are primarily produced in pairs
mainly from qqbar Top decays as free quark BR(t
ÆWb) @ 100 %
3 classes of signal
Dilepton: Clean but small statistics: BR 5%
Lepton + jets: Larger statistics Higher background:
BR 30%All-hadronic: Higher statistics Huge background: BR 44%
Branching ratios for tt decay modes
Production and decay of Top quark
e-e(1/81) mu-mu (1/81) tau-tau (1/81) e -mu (2/81) e -tau(2/81) mu-tau (2/81) e+jets (12/81) mu+jets(12/81) tau+jets(12/81) jets (36/81)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Data
0.07±0.04 0.09±0.05 0.04±0.03 0.10 ±0.07
5
0.30±0.12 Background
2.5±0.03
Expected (σ=7pb)‡
Z →ττ WW/WZ QCD DY
CDF:Dilepton Channel
• Event selection
– 2 High P
T(P
T>20 GeV) oppositely charged leptons (ee,µµ,µe) |η|<1.
– Both isolated: I
CAL< 0.1 – Large missing E
T> 25 GeV
– at least 2 jets with E
T> 10 GeV – Total transverse energy of the
event (H
T)> 200 GeV
– Veto Z’s, cosmics, and conversions
•BR~5%, detection eff ~ 11%, expect S/B~9, S~2.5
•5 candidate events in 72 pb
-1‡ σ
tt(@ √s = 1.96 TeV and M
top=175 GeV/c
2) = 6.70
+0.71-0.88pb From Cacciari et al (hep-ph/0303085)
fro m da ta
fro m M C
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Met : Dilepton Events
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
σ tt = 13.2 ± 5.9 stat ± 1.5 syst pb
NLO for M
NLO for M
top top= 175 = 175 GeV GeV : 6.70 : 6.70
+0.71+0.71-0.88-0.88pb pb
CDF:Dilepton cross section (ee,µµ,eµ)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Dilepton e-µ
Run/Event 155114/478702
muon
electron
electron
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
• Event selection
– 1 High momentum,
central(|η|<1), and isolated lepton
– P
T>20 GeV/c, e or µ.
– Large missing E
T> 20 GeV – 3 or more jets with E
T> 15
GeV
– Veto Z’s, cosmics, and conversions
– at least 1 jet with secondary vertex tag (SVX)
• 15 observed events in 57.5 pb
-1• Backgrounds from
Wbb,Wcc,mistags,Wc, non-W (Data and MC): 3.8 ± 0.5
CDF: Lepton+Jets
signal
control
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
W+jet Background composition
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
CDF: b-tagging from Secondary Vertex
Kinematical distributions for b-jets MC data
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
µ +4jets(+2 SVX tag)
Run/Event 153693/799494
MET 40.2 GeV
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
CDF: tt cross section measurement
Dilepton
Theory (NLO)
Mtop=175 GeV/c2
√s=1.96 TeV
6.7 +0.71
-0.88
13.2 ± 5.9 stat ± 1.5 syst 5.3 ± 1.9 stat ± 0.8 syst Lept+Jet
CDF σ ttbar (pb) @ √ s=1.96 TeV
Run II (Lept+Jet) Run I CDF
combined
From Cacciari et al (hep-ph/0303085)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Luminosity:
Selection Criteria: 42.6 pb -1 (µµ)
2 Isolated muons, MET,H T and more than 2 jets
Data Signal (MC)
WW (MC) Z-> µµ
DØ:Dimuon channel
Data 2
0.60±0.30 Background
0.3±0.04 Signal (σ=7pb)
0.20±0.11 0.20±0.20 0.18±0.18 0.02±0.02 0.00±0.00 Z →µµ
DY →µµ QCD Z →ττ WW
From Data From MC
x
x
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Luminosity:
Selection Criteria: 33.0 pb -1
1 electron, 1 isolated muon, H T (e) and more than 2 jets
H
T(e) (GeV) N
jetsZ →ττ Z
Fakes Fakes
Data 1
0.07±0.01 Background
0.5±0.01 Signal (σ=7pb)
0.05±0.01 0.02±0.02 0.00±0.00 QCD Fakes
Z →ττ WW
DØ: Dilepton (eµ)
From Data
From MC
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Luminosity: e+jets 49.5pb -1 µ +jets 40.0pb -1 Preselection:
lepton with Pt>20 GeV/c MeT>20 GeV
Njet>=4
veto non-isolated soft muon
Evaluate W+4 jet scaling from W+n jets
Topological Selection
|η
W|<2.5 and E
T(W)>60 GeV H
T>220 GeV
Aplanarity>0.065
DØ: Lepton+Jet
α = 0.145±0.02 α = 0.164±0.02
) (
) ) 1 (
(
jets jets
n W
n W
+ +
≡ +
σ α σ
Behrends scaling:
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
µ -
MTC
Jet 3 Jet 1
Jet 2
Jet 4 Jet 5
µ +jet Candidate event
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Preselection: Topological + Aplanarity>0.04
3 jets with Et>20 GeV and |η|<2 H
T>110 GeV
Soft Muon Tag:
Pt(µ)<4 GeV/c
∆ R<0.5
Strategy: Use semileptonic b decay to identify b-jet
DØ:Lepton+Jet (Soft Muon Tag)
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
DØ:Cross Section Measurement
pb (lumi) 0.8
(syst)
(stat) 8.4
σ =
+−4.53.7 +−5.33.5±
Combining measurements
from the different decay
channels
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
METHOD
Use 2C constrained fitting technique with constraints M
ιν= M
W, M
jj=M
W, M
t1=M
t224 combinations:
12 correspond to the jet parton match
every combination has 2 solutions for neutrino P
ZChoose combination with lowest χ
2.
l ν
W +
W - t t
b-jet
b-jet
jet jet
X
Select lepton + 4 jet events, similar to the σ(tt)
lepton+jet measurement, except no requirement on silicon.
CDF: Top Mass
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Reconstructed top masses from data are compared to parameterized templates of top and background Monte Carlo.
signal
background
CDF:Top Mass
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Use a continuous likelihood method to extract top mass and
statistical uncertainty
CDF: Top Mass
RunI Uncertainty was 4.4 !
We know how to improve it!
M
Top Run(II)=171.2±13.4±9.9 GeV/c
2A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Top Mass: b-tag
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
M Top : Run II Perspectives
Full Run IIa Luminosity: 2 fb
-1Larger statistics for the signal sample
Larger number of control
sample Î Smaller systematics
Run II expectations in 2 fb
-1Channel
Dilepton (e,m) Dilepton t
Lepton+3 jet/+1 btag Lepton +4 jet/+2 btag
155 19 1520/990 1200/240
∆ M top ~3 GeV/c 2
Run IIa
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Tevatron may play a role with low mass range M H .
•gg->H
•Huge background for
H->bb (may be H->ττ/WW)
•Associated Production (HW/HZ) with H->bb
Most promising channel!
•qqHqq and ggHQQ Overwhelmed by background
SM Higgs Production and Decay
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
SM Higgs: Run I and Run II
Run I W/Z H and H->bb
Direct searches:
factor 30 below SM!
RunII Combined Higgs Sensitivity
Subject to a critical re-evaluation based on RunII experience.
LEP excluded at 95% C.L.
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
W/Z+jets production:DØ
•Key for W/Z associated production
•Select a clean sample of W/Z + jets (using leptons)
•Understand background, tune MC, etc...
2
ndleading jets 1
stleading jets
GeV QCD BKG
QCD BKG
Dot : Data Bar : MC
GeV
Di-jet Mass W(eν)+jets
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Z+jets production:DØ
Combined Z(ee)+jets and Z(µµ)+jets
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Tools for Higgs Searches
Combine CDF and DØ results: Advanced Statistical Tools B-tagging: (cf. CDF:Lepton+Jet)
Jet corrections: Improve M
bbresolution with specific corrections Z->bb
(Data RunI) Specific b-jet
corrections
A. Sidoti INFN Pisa and University
IFAE Lecce 2003
Perspectives
Tevatron
A. Sidoti INFN Pisa and University