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Tevatron Run 2 Physics Tevatron Run 2 Physics ResultsResults
Dhiman ChakrabortyNorthern Illinois University
for
The D0 and CDF The D0 and CDF collaborationscollaborations
ACFA workshop15-17 December, 2003
TIFR, Mumbai, India
Dhiman Chakraborty Tevatron Run 2 Physics Results 2
OutlineOutline• Introduction
– The collider upgrade - Tevatron Run 2– The detector upgrades – CDF & D0
• New Physics results– QCD– Bottom– W/Z– Top– Higgs– New Phenomena
• Summary & Outlook
Dhiman Chakraborty Tevatron Run 2 Physics Results 3
The Tevatron Collider in The Tevatron Collider in Run 2Run 2
• Proton-antiproton collisions at s = 1.96 TeV
• 36 bunches each of p & p 396 ns between bunch crossings – Increased from 6x6 bunches
with 3.5ms in Run 1
• Increased instantaneous luminosity:– Run 2 goal: 30 x 1031 cm–2 s-1
– Current: ~4.5 x 1031 cm–2 s-1
• Projections through FY 2009:– “Base”: 4.4 fb-1
– “Design”: 8.6 fb-1
Dhiman Chakraborty Tevatron Run 2 Physics Results 4
Run 2 luminosity profileRun 2 luminosity profile
• Lint~300 pb-1 delivered by the Tevatron
• Good quality data since Spring 2002• D0 & CDF collecting data with 85%-90% eff.
Projection for 2004:additional 310-380 pb-1
delivered
The Tevatron Collider The Tevatron Collider ExperimentsExperiments
19 countries83 institutions, 664 physicists
Dhiman Chakraborty Tevatron Run 2 Physics Results 6
The upgraded D0 Run 2a The upgraded D0 Run 2a detectordetectorMultipurpose collider detector:
Tracking
● silicon vertex detector● fiber tracker● 2T magnetic field
Calorimetry - preshowers - U/LAr calorimetersMuon - drift tubes and scintillatorTrigger+ Data Acquisition System
Dhiman Chakraborty Tevatron Run 2 Physics Results 7
•New bigger silicon, new drift chamber•Upgraded calorimeter, muon system•Upgraded DAQ/trigger, esp. displaced-track trigger
The upgraded CDF Run 2a The upgraded CDF Run 2a detectordetector
Dhiman Chakraborty Tevatron Run 2 Physics Results 8
The new silicon The new silicon detectorsdetectors
6 Barrels
12 F-disks 4 H-disks
Common features:•Coverage of the luminous regions•Extended acceptance at large pseudo-rapidity•3D Tracking capability •Excellent I.P. resolution
D0
CDF
Dhiman Chakraborty Tevatron Run 2 Physics Results 9
QCDQCDInclusive jet cross section vs. NLO predictions
•Theoretical uncertainties dominated by PDF’s
• Full Run 2 data set will help reduce this uncertainty
• So far the data agrees reasonably well with NLO predictions
Dhiman Chakraborty Tevatron Run 2 Physics Results 10
• Search for new phenomena, e.g. compositeness (qq, qg, gg)
• Sensitive to gluons at large x
QCDQCDDijet mass vs. NLO predictions
Dhiman Chakraborty Tevatron Run 2 Physics Results 11
Heavy flavor: B hadronsHeavy flavor: B hadronsSeveral new measurements on masses, lifetimes & branching fractions of B hadrons performed by both CDF and D0, manymore, such as Bs oscillation, M(Bc), & B(Λb), coming soon.
B hadron mass measurements using fully reconstructed decays:
Bs and b measurements world’s best:
CDF result: M(Bs)=5365.5 1.6 MeV
World avg: M(Bs)=5369.60 2.40 MeV
CDF result: M(b)=5620.4 2.0 MeV
World avg: M(b)=5624.4 9.0 MeV
Bd** B
5.71 ± 0.016 GeV 5.71 ± 0.016 GeV (PDG: 5.698 ± 0.008 GeV)
1st observation at Tevatron
Dhiman Chakraborty Tevatron Run 2 Physics Results 12
mass: 5.272 ± 0.005 GeV
Lifetime:
1.671 ± 0.018 ps (PDG)
1.650.08(stat.) 0.120.10 (sys.) ps
B J/K
Bs lifetime - 1.33± 0.14(stat)
±0.02(sys) ps
PDG: 1.461 ± 0.057 ps
Bs→J/ψ Φ with J/ψ→μ+μ- and
Φ→K+K- B+→ J/ΨK+, B0 →J/ΨK*0 check
technique, systematics
BT
Bxy p
mLct
Heavy flavor: B hadron Heavy flavor: B hadron lifetimeslifetimes
Dhiman Chakraborty Tevatron Run 2 Physics Results 13
Use fully reconstructed b J/ with J/ + and p
Lxy
+p
primary
Mb560025MeV
Only at the Tevatron !
Heavy flavor: Heavy flavor: b lifetimelifetime
Dhiman Chakraborty Tevatron Run 2 Physics Results 14
Heavy flavor: Heavy flavor: new particle decaying to new particle decaying to
J/J/ππ++ππ
Belle observes narrow statefinal state J/π+π • exclusive: B+ →J/π+π K+
• 35.7 ±6.8 events• possibly charmonium• mass is unexpected• shown August 12, 2003
CDF confirms this onSeptember 20 • final state J/π+π • mostly prompt prodction• 709±86 events
Dhiman Chakraborty Tevatron Run 2 Physics Results 15
Heavy flavor: Towards a Measurement of BHeavy flavor: Towards a Measurement of Bss MixingMixing
• Bs reconstruction – e.g.
• Flavor tagging ( Bs or Bs at the time of production?)– Tagging “dilution”: D=1-2w– Tagging power proportional to: D2
• Proper decay time
– Crucial for fast oscillations (i.e. Bs)
s sB D
Typical power (one tag):
D2 = O(1%) at Tevatron
D2 = O(10%) at PEPII/KEKB
T
xy
pBct
xy xy B
TL
T T
L L mct
m
p ppct
uncertainty
Dhiman Chakraborty Tevatron Run 2 Physics Results 16
Bs->Ds ln
opposite side soft muon tagging:
tagging power:1.6%
opposite side jet charge tagging:
Heavy flavor: Towards a Measurement of BHeavy flavor: Towards a Measurement of Bss MixingMixing
Dhiman Chakraborty Tevatron Run 2 Physics Results 17
Electroweak: Z Electroweak: Z →l→l++ll−−
Ncand = 1631
∫L = 72 pb-1
εtotal = 9%
Z→μ+μ−:CDF Event selection:• Two central tracks:
– pT > 20 GeV, opposite charge, MIP trace in CAL
– at least one |η| < 0.6, both |η| < 1.0
• 66 < Mμμ < 116 GeV , Cosmic veto (bkg <1%)
CDF: σZ • B(Z→μ+μ−) = 246 ± 6 ± 12 ± 15 pb
stat. syst. lumi.
D0: σZ • B(Z→μ+μ−) = 261.8 ± 5.0 ± 8.9 ± 26.2 pb
stat. syst. lumi.Ncand = 1631
∫L = 42 pb-1
Z→e+e−:Two isolated electrons, ET > 25 GeV, |η| < 1.1
CDF: σZ•B(Z→e+e−) = 267.0 ± 6.3 ± 15.2 ± 16.0 pb lumi. stat. syst.
DØ: σZ•B(Z→e+e−) = 275 ± 9 ± 9 ± 28 pb lumi. stat. syst.
Dhiman Chakraborty Tevatron Run 2 Physics Results 18
Electroweak: looking for ZElectroweak: looking for Z→ → ++−−• Look for isolated, high pT e or μ opposite narrow
hadronic jet
CDF DØ
• • small numbers of• candidates• • rates consistent • with expectations
Dhiman Chakraborty Tevatron Run 2 Physics Results 19
Electroweak:Electroweak: ((W→lW→l)) • pT(e) > 25 GeV, ET
miss > 25 GeV
OR• pT(μ) > 20 GeV, ET
miss > 20 GeV
D0:σW • B(W→e)
= 2.884 ± 0.021 ± 0.128 ± 0.284 nbσW • B(W→μ)
= 3.226 ± 0.128 ± 0.100 ± 0.322 nb
CDF:σW • B(W→e)
= 2.64 ± 0.01 ± 0.09 ± 0.16 nbσW • B(W→μ)
= 2.64 ± 0.02 ± 0.12 ± 0.16 nb(all uncertainties are stat. ± syst. ±
lumi.)
Dhiman Chakraborty Tevatron Run 2 Physics Results 20
Electroweak:Electroweak: (ratio & (ratio & widths)widths)
R = σW • B(W→l)
σZ • B(Z→l+l−) • Luminosity, pdf, some expt. sys.
uncertainties cancel• R = 10.34±0.35 (stat)±0.48 (sys)
Indirect measurement of ΓW :
Using NNLO calculation of the cross section ratio and the LEP measurement of B(Z→l+l−), one can extract B(W→l). The SM prediction for Γ (W→l) then gives ΓW = Γ (W→l) / B(W→l):
Dhiman Chakraborty Tevatron Run 2 Physics Results 21
HiggsHiggs• D0 & CDF are picking up searches for SM-like Higgs where LEP left it off.• Must look hard despite limited sensitivity.• While LEP expts are now rigorously studying a broad spectrum non-SM
scenarios, Tevatron expts. Are focusing on MSSM, with the expectation of a light SM-like Higgs.
Dhiman Chakraborty Tevatron Run 2 Physics Results 22
Higgs sensitivity at the Higgs sensitivity at the TevatronTevatronThe 1998-99 FNAL study updated in Sep 2003 with
– Hit-level simulations– Background modeling based on Run 2 data and improved analysis techniques– Focus on 115 Gev < M(H) < 140 GeV (lowered expectation for int lum)– Focus on pp -> Wh -> lnubb (CDF) and pp -> Zh -> nunubb – Results combined for both channels and experiments.
Despite optimistic assumptions in the previous study, the newer study suggests that we can do better than we thought 5 yrs ago.
With 4-5 fb**-1, DO+CDF together may be able to exclude M(H)<130 GeV at 95% CL if it isn’t there.
Note: systematic uncertainties have not been taken into account.
Dhiman Chakraborty Tevatron Run 2 Physics Results 23
Doubly charged Doubly charged HiggsHiggs
• appear in left-right symmetric models• for M(H±±) < 160 GeV, dilepton decay modes dominate• 107 pb-1
• M(H±±) > 95 GeV @ 95% c.l. (right-handed)• M(H±±) > 115 GeV @ 95% c.l. (left-handed)
– world’s best limit
pp H H
Dhiman Chakraborty Tevatron Run 2 Physics Results 24
TopTop • top-antitop production– mainly quark-antiquark
annihilation
• W and b-quark decays specify final states– isolated high PT leptons– soft leptons in jets– detached vertices in jets
Dhiman Chakraborty Tevatron Run 2 Physics Results 25
Top: tagging high-pT b Top: tagging high-pT b jetsjets
Silicon Vertex Tag• Signature of a b decay is
a displaced vertex:– Long lifetime of b
hadrons (c ~ 450 m)+ boost
– B hadrons travel Lxy~3mm before decay
with large charged track multiplicity
Soft Lepton Tag• Exploits presence of e/ in
semileptonic decays– On average, hese leptons
have lower pT than those from W/Z,
– and are not as isolated B-tagging at hadron machines established:•crucial for top discovery in RunI •essential for RunII physics program
Dhiman Chakraborty Tevatron Run 2 Physics Results 26
D0 Run II preliminary - L=45 pb-1
• 1 high pT lepton(e,m)
• Large Missing ET
• 3 central jets
This signature suffers from largeW+jets background. Isolate signal using:SVX B-tag and/or kinematics
Top: Run 2 cross section Top: Run 2 cross section (l+jets)(l+jets)
Dhiman Chakraborty Tevatron Run 2 Physics Results 27
0.9(lum)(syst)(stat)8.7 2.72.0
6.44.7
(syst)(stat)7.6 1.51.9
3.83.1
1.7(syst)3.4(stat)7.3
0.7(lum)(syst)(stat)7.4 2.11.8
4.43.6
1.1(lum)(syst)(stat)10.8 2.12.0
4.94.0
0.5(lum)(syst)(stat)4.6 2.12.0
3.12.7
1.1(lum)(syst)(stat)11.4 2.01.8
4.13.5
0.8(lum)(syst)(stat)8.0 1.71.5
2.42.1
0.9(syst)1.9(stat)5.3 2.1(syst)1.8(stat)5.1
0.8(lum)(syst)(stat)8.1 1.61.4
2.22.0
Top: Run 2 cross section Top: Run 2 cross section summary (pair production)summary (pair production)
Dhiman Chakraborty Tevatron Run 2 Physics Results 28
• Template method:– Kinematic fit under the tt
hypotesis– Combinatorial issues– best 2 combination chosen– Likelihood fit
• Dynamical method:– Event probability of being
signal or background as a function of m(t)
– Better use of event information increase statistical power
– Well measured events contribute more
New D0 Run 1 result: factor of 2.5 improvement on the statistical uncertainty!
25.4GeV/c180.1 D0 l+jets
Top: Mass Measurement Top: Mass Measurement (Run 1)(Run 1)
Dhiman Chakraborty Tevatron Run 2 Physics Results 29
A precise measurement of the top mass combines cutting edge theoretical knowledge with state of the art detector calibration
CDF Run 2 preliminary, 108 pb-1
D0 Run 2 preliminary
Mass in l+jets channel with a b-tagged jet 212.7
9.4 GeV/c 7.1(syst)(stat)177.5
CDF Run 2 preliminary, 126 pb-1
Mass in dilepton channel 217.4
16.9 GeV/c 7.9(syst)(stat)175.0
Top: Mass Measurement Top: Mass Measurement (Run 2)(Run 2)
Dhiman Chakraborty Tevatron Run 2 Physics Results 30
• Multitude of choices for models/params• generic MSSM • vs.• SUGRA, cMSSM, RPV, GMSB, AMSB, …
• There is no absolute exclusions in SUSY• Use theories only as guides and• Concentrate on experimental signatures
rather than individual models• After all, he real goal and hope is to find
something…
CDF has searched for in Run 2
and D0 for
A lot of emphasis also on signatures with
photons and ’s.
New Phenomena: SUSYNew Phenomena: SUSY
Dhiman Chakraborty Tevatron Run 2 Physics Results 31
ee
•Appear in several extensions to the SM: GUTs, RPV SUSY, TC, …• Carries both lepton & baryon numbers• Pair production most likely at Tevatron• Assume coupling to l & q of same generation only, to avoid FCNCs• Most combinations of charged & neutral leptons of the 1st two generations analyzed.• Run 2 data so far consistent with expected background
New Phenomena: New Phenomena: leptoquarksleptoquarks
Dhiman Chakraborty Tevatron Run 2 Physics Results 32
New Phenomena: Z’ to New Phenomena: Z’ to dileptonsdileptons
• Look for narrow resonance beyond M(Z) in dilepton mass spectrum• No significant excess over expected background in Run 2 data yet
Z’()Z’(ee)
Dhiman Chakraborty Tevatron Run 2 Physics Results 33
New Phenomena: small & New Phenomena: small & large EDslarge EDs Analysis similar to Z’ search
CDF: m_g>600 GeV at 95% CL
for Small (warped) ED (Randall-Sundrum)
D0: MS(GRW) > 1.37 TeV @ 95% CL (incl. Run 1)
for Large (flat) EDs (Arkani-Hamed, Dimopoulos, Dvali)
Dhiman Chakraborty Tevatron Run 2 Physics Results 34
New Phenomena: other New Phenomena: other resultsresults
CDF has searched for
in
windows about the B meson masses: best limits, still O(100) above SM predictions, but near SUSY enhancement scenarios.
D0 has performed a model-independent search for deviations in data from SM predictions for eevents (a la Sleuth)SM background: Ztt, WW, ttbar, fake isolated leptonsData:
–e: 1.8 ± 0.1 expected, 2 obs.–ej: 0.1 evt expected, 0 obs.
Dhiman Chakraborty Tevatron Run 2 Physics Results 35
Summary & OutlookSummary & Outlook Run 2 of the Tevatron has already produced
many new results on b, electroweak, Higgs, top, & New Phenomena- Most have already superceded Run 1 results,- Several measurements are world’s best.
Many many more are on their ways: stay tuned as theintegrated luminosity grows and our understanding of the detectors’ performance improves.
We’ve entered a new territory in discovery potential for physics beyond the SM.
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