tevatron run 2 physics results dhiman chakraborty northern illinois university for the d0 and cdf...

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


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


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


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


•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


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


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


• Search for new phenomena, e.g. compositeness (qq, qg, gg)

• Sensitive to gluons at large x

QCDQCDDijet mass vs. NLO predictions


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


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


Use fully reconstructed b J/ with J/ + and p

Lxy

+p

primary

Mb560025MeV

Only at the Tevatron !

Heavy flavor: Heavy flavor: b lifetimelifetime


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


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


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


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.


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


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.)


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):


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.


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.


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


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


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


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)


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)


• 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)


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)


• 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


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


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)


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)


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.


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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