Post on 05-Jan-2016
FNAL Users’ Meeting, 06/02/03, p. 1
Top and Electroweak Results from CDF
Igor Volobouev
LBNL
for the CDF Collaboration
CDF
FNAL Users’ Meeting, 06/02/03, p. 2Igor Volobouev
Top / Electroweak Program
• Measurement of fundamental parameters Calibration (e.g., MZ ) Precision measurements of Mtop, MW, Vtb, etc.
• Tests of Standard Model predictions Cross sections, branching fractions, kinematical
distributions, lepton universality Top quark properties: unique to CDF/D0
• Searches for new phenomena Higgs Anomalous couplings, new particles and resonances, rare
and forbidden decays
• Discovery potential exists in all areas
CDF
FNAL Users’ Meeting, 06/02/03, p. 3Igor Volobouev
TOF
=2
=3
=1
CDF Run 2 Upgrade
• Improved Si coverage || < 2 up to 8 layers
• New central tracker 96 layers
• Time of Flight
• Expanded muon system
• Forward calorimeter
• Trigger and electronics
= -ln(tan(/2))
CDF
FNAL Users’ Meeting, 06/02/03, p. 4Igor Volobouev
Run 2 Data Sample
• Total current sample on tape: 175 pb-1
• “Winter analyses” sample: 56-91pb-1
• 4-9 pb-1/week90% efficiency
“Winter” sample
Commissioning
DeliveredOn Tape
Store Number
Tot
al L
umin
osity
(pb
-1)
CDF
FNAL Users’ Meeting, 06/02/03, p. 5Igor Volobouev
Electroweak Measurements
• Unambiguous predictions from the Standard Model, world averages, Run 1 measurements W, Z production cross sections Lepton universality Forward-backward asymmetry Di-boson production
• “New physics” reach at a few hundred pb-1
• Data analysis infrastructure Lepton and photon identification W and Z signatures Calibrations Luminosity monitoring
We
Z
CDF
FNAL Users’ Meeting, 06/02/03, p. 6Igor Volobouev
B(Wll)
Events Background •B(Wll) (nb)
e 38625 6% 2.64±0.01stat±0.09sys±0.16lum
21599 11% 2.64±0.02stat±0.12sys±0.16lum
• Clean signature Isolated lepton Missing ET
• High and S/B
• 72 pb-1
W
CDF
FNAL Users’ Meeting, 06/02/03, p. 7Igor Volobouev
Wand Lepton Universality
• Narrow, isolated hadronic jet from
• Missing ET > 25 GeV
• Electrons removed• Relatively low
background ( 26%)
sysstateWBR
WBR07.004.099.0
)(
)(
B(W) = 2.62 ± 0.07stat ± 0.21sys ± 0.16lum nb
CDF
FNAL Users’ Meeting, 06/02/03, p. 8Igor Volobouev
B(Zll)• Two leptons: negligible
background (< 1%)• Used for calibrations: energy
scale, resolutions
l =e: 267±6stat±15sys±16lum pb
l =: 246±6stat±12sys±15lum pb
CDF
FNAL Users’ Meeting, 06/02/03, p. 9Igor Volobouev
AFB with Z0/* e+e-
• Forward-backward asymmetry:)0(cos)0(cos
)0(cos)0(cos
dd
ddAFB
• Probes /Z interference, sensitive to new physics
• High mass reach is unique to Tevatron
• Measurement is consistent with the SM prediction
CDF
FNAL Users’ Meeting, 06/02/03, p. 10Igor Volobouev
• pp W, Z, WW• Depend on trilinear gauge
couplings (s-channel):
• Events found expected W Z WW 4.3
• Results are statistics-limited, consistent with the SM predictions
Di-boson Cross Sections
W
W
q
q'81 events
CDF
FNAL Users’ Meeting, 06/02/03, p. 11Igor Volobouev
Top Quark Measurements
• Main question: is top quark adequately described by the Standard Model?
• Run 2 results so far: Cross section Top mass
• Many precision tests of top to come with more data
• SM: tt production cross section at 1.96 TeV is 30% larger than at 1.8 TeV
Top spin polarization
Production Cross Section
Resonance production ?
Production kinematics
CDF
FNAL Users’ Meeting, 06/02/03, p. 12Igor Volobouev
Dilepton Cross Section
• Signature: 2 leptons, 2 jets, missing ET
• Backgrounds: WW, Z , Drell-Yan, fake leptons
• Event selection: signature and Scalar transverse energy > 200 GeV Background rejection: photon
conversion veto, Z veto, lepton isolation, for missing ET
• Found 5 candidates, expected 0.3 background events
tt =13.2 ± 5.9stat ± 1.5sys pb
CDF
FNAL Users’ Meeting, 06/02/03, p. 13Igor Volobouev
Lepton + Jets Cross Section
Control Signal15 candidate events with b tags, 3.8 background
tt = 5.3 ± 1.9stat ± 0.8sys pb
CDF
FNAL Users’ Meeting, 06/02/03, p. 14Igor Volobouev
Lepton + Jets Cross Section
Control Signal15 candidate events with b tags, 3.8 background
tt = 5.3 ± 1.9stat ± 0.8sys pb
CDF
FNAL Users’ Meeting, 06/02/03, p. 15Igor Volobouev
tt Cross Section Summary
hep-ph/0303085 (M. Cacciari et al)
CDF
FNAL Users’ Meeting, 06/02/03, p. 16Igor Volobouev
Top Quark Mass
• Lepton + jets channel: Run 1 CDF result was
176.1 ± 6.6 GeV/c2
• Statistical error is mainly due to jet combinatorics. Mtop with b tags will be presented at the summer conferences.
• Systematic errors will dominate the uncertainty Jet energy reconstruction MC top decay modeling Background
33 events
CDF
FNAL Users’ Meeting, 06/02/03, p. 17Igor Volobouev
Future Run 2 Measurements
• Electroweak Drell-Yan at high mass
(PDFs, new physics) W charge asymmetry Direct W width pp WZ, ZZ, trilinear
couplings MW with 40 MeV/c2
precision (400 pb-1 are needed if 1/L scaling holds)
• Top Analysis of production and
decay kinematics– Resonant production
– W helicity
– Spin correlations
Single top production Vtb
Rare and forbidden decays Mt with 3 GeV/c2
precision
Many of these measurements are already in the works
CDF
FNAL Users’ Meeting, 06/02/03, p. 18Igor Volobouev
Higgs ConstraintCurrent SM Higgs fit: MH = 81+52
–33 GeVLEP 2 direct search limit: MH > 114.4 GeV at 95% CL
CDF
FNAL Users’ Meeting, 06/02/03, p. 19Igor Volobouev
Summary
• A variety of Run 1 results have been reestablished We are confident that CDF components are working as
expected and the system integration was a success Our understanding of the CDF detector is improving. We
have already developed many building blocks needed for taking on really challenging physics problems.
• So far, top and electroweak results are consistent with the Standard Model predictions
• Most measurements are statistics limited, and will benefit from larger datasets
• Expect many new and improved Run 2 results this summer and during the next few years
CDF
FNAL Users’ Meeting, 06/02/03, p. 20Igor Volobouev
Backup Slides
CDF
FNAL Users’ Meeting, 06/02/03, p. 21Igor Volobouev
Electron Identification
• CEM transverse energy ET > 20 GeV
• Track pT > 10 GeV/c
• Track |z0| < 60 cm
• ET/pT < 2.0 when ET < 50 GeV
• Cluster EHAD/EEM < 0.055 + 0.00045 * E
• Track-to-shower match 3 cm
• Fractional calorimeter energy isolation < 0.1
• Shower profile consistent with electron
• Fiducial to CES
CDF
FNAL Users’ Meeting, 06/02/03, p. 22Igor Volobouev
Muon Identification
• Track pT > 20 GeV/c
• Track |z0| < 60 cm
• Cosmic ray veto
• EEM < 2 + max(0, 0.0115 * (p - 100)) GeV
• EHAD < 6 + max(0, 0.0280 * (p - 100)) GeV
• Fractional calorimeter energy isolation < 0.1
• Track match to a muon chamber stub: 3, 5, and 6 cm for CMU, CMP, and CMX, respectively
CDF
FNAL Users’ Meeting, 06/02/03, p. 23Igor Volobouev
B Jet Tagging with SVX
• At least two well-reconstructed tracks with 3 silicon hits
• Secondary vertex LXY significance at least +3• Efficiency in tt events: 45 1 5 % for “taggable” jets
CDF
FNAL Users’ Meeting, 06/02/03, p. 24Igor Volobouev
Weekly Delivered Luminosity
CDF
FNAL Users’ Meeting, 06/02/03, p. 25Igor Volobouev
Downtime and Deadtime
• Downtime – much better when we keep taking data…– HV Trips (COT, Silicon, muon, etc.) (not so often these days)– L3/EVB/CSL/L2, etc. (comes/goes in wave. Right now, it is good)– HRRs (bunch counter errors, TDC done timeout, etc.)– Trigger table tests, 2 SRC tests, XFT tests… (future investment)– Startup time, waiting to bring up HV at beginning of the store– Silicon D-mode calibration and other odds and ends– Downtime due to operator errors are very small
• Dead time – much easier when lumi is low and trigger rates low, but…– L1/L2 busy dead time (much work in progress, eg. 2SRC readout)– Hitting CSL output limit -- design 20Mb/sec. This current problem should be
solved by:• Tightening (wisely) trigger filters, limiting L3 output rates• Dropping L3 reconstruction banks and other diagnostic banks• Compressing silicon/COT raw data banks, etc.
– However, at the same time, we are also reviewing/studying the possibility/consequence of extending the current CSL 20Mb/sec limit
CDF
FNAL Users’ Meeting, 06/02/03, p. 26Igor Volobouev
Di-boson Run 2 Results
Cross section for ET() > 7 GeV, R > 0.7 :(W) = 17.2 3.8(stat.) 2.8(sys.) 1.0(lum.) pbSM: (W) = 18.7 1.3 pb
W, electron channel
(W) = 19.8 4.5(stat.) 2.4(sys.) 1.2(lum.) pbSM: (W) = 18.7 1.3 pb
W, muon channel
= 5.8 1.3(stat.) 0.7(syst.) 0.3(lum.) pbSM: = 5.3 0.4 pb
Z, combined
WW: expected 2.8 signal and 1.5 background events (SM), found 2