Tevatron Results and Future Prospects

Russian Academy of Sciences Nuclear Physics Session

November 23, 2009 - ITEPDmitri Denisov, Fermilab

Tevatron Results and Future Prospects

Disclaimer: DØ is used for majority of the examples, CDF in most cases has Ø is used for majority of the examples, CDF in most cases has similar resultssimilar results

Outline

The Tevatron

Detectors and dataDetectors and data

Highlights of the recent Tevatron results

Standard Model Higgs searches

Future Tevatron experimental program

Summary

Dmitri Denisov, RAS, November 2009 2

Tevatron: Proton-antiproton Tevatron: Proton-antiproton ColliderCollider

82.32.5Interactions/ crossing

3963963500Bunch crossing (ns)

50173 Ldt (pb-1/week)

3 10329 10311.6 1030Typical L (cm-2s-1)

1.961.961.8s (TeV)

36 3636 366 6Bunches in Turn

Run IIbRun IIaRun I

Run I Run IIa Run IIb 0.1 fb-1 ~1fb-1 ~12 fb-1

Energy and luminosity

Nevents (sec-1) = L

World highest energy collider1.96 TeV center of mass

energy

Run IIa Run IIb

Tevatron PerformanceTevatron Performance• Peak luminosity is 3.5.1032 cm-2sec-1

– A lot of anti-protons made!• Reliable operation of very complex

accelerators– In stores ~120 hours/week

• Total 7.2 fb-1 delivered in Run II• Integration rate is steadily raising

3

7.2 fb-

1

Integrated Luminosity vs Fiscal Year

Performance continues to improve!

Peak Luminosity

Dmitri Denisov, RAS, November 2009

FY2010

2009

2002


Precision tests of the Standard Model– Weak bosons, top quark, QCD, B-physics…

Search for particles and forces beyond those known– Higgs, supersymmetry, extra dimensions….

Tevatron Physics GoalsTevatron Physics Goals

Fundamental Questions

Quark sub-structure?

Origin of mass?

Matter-antimatter asymmetry?

What is cosmic dark matter? SUSY?

What is space-time structure? Extra dimensions?…


Tevatron DetectorsTevatron Detectors

Driven by physics goals, the detectors

emphasize

Electron, muon and

tau identification

Jets and missing transverse

energy

Flavor tagging through

displaced vertices

6

The DØ CollaborationThe DØ CollaborationDØ is an international collaboration of

510 physicists from 18 nations who have designed, built and operate the DØ detector at the Tevatron and perform data analysis

Institutions: 89 total, 38 US, 51 non-US Collaborators:~ 50% from non-US institutions with strong European involvement~ 100 postdocs, 110 graduate studentsDmitri Denisov, RAS, November 2009

7

• DØ experiment is smoothly recording high quality physics data – Typical week ~50 pb-1

• On average 92% data taking efficiency

• As of today DØ has ~6.5 fb-1 on tapes– Was ~4.9 fb-1 on tapes at 2008

RAS meeting– All detectors functioning well

Data CollectionData Collection

Preliminary Results


Many results published

November 20092002

Most results published

November 20092002

Experimental ChallengesExperimental Challenges

Average number of interactions per crossing is reaching ~10 at 3.1032 cm-2sec-1


• Radiation doses of the inner silicon layer are reaching Mrads levels

• Carefully monitoring silicone performance

• Layer 1 (one out of 5 layers) will become under depleted after ~8 fb-1

• All other layers are far from been affected

• No deterioration of tracking performance is expected up to ~12 fb-1

A zero bias DØ data event at 0.6.1032 cm-2sec-1 ... and at 2.4.1032

cm-2sec-1

TriggeringTriggering

Typical store with starting luminosity of 3.5 .1032 cm-2sec-1

All high pt triggers are un-prescaled at all luminosities



Detectable Objects – Particle Detectable Objects – Particle IdentificationIdentification

Muons

Jets

Final decay products electrons

muons charged tracks

jets (b) missing Et ()

Detection and MC optimization using well known objects

Electrons

Zee

Z

• Excellent understanding of the detector and algorithms achieved

• Took many years…

• Certification of additional data for identification methods within a few weeks

• Automated software

~2%

Rapidity

b-tagging

Continuing ImprovementsContinuing Improvements

Optimizing muon acceptance bytriggering on jets and missing

energy

Tagging of b-jets with Neural Network

11Dmitri Denisov, RAS, November 2009

• Measured in the widest kinematic region– In rapidity and transverse

momentum• 8+ orders of magnitude changes• In agreement with pQCD predictions


Use partons scattering to study proton structure Quarks sub-structure? Rutherford style experiment

Measure QCD parameters and structure functions

Determine Jet Energy Scale Critical for top mass and Higgs searches

Understand the backgrounds to physics beyond Standard Model

QCD StudiesQCD StudiesInclusive jet cross sections

Pt, GeV

Di-jet ResonancesDi-jet Resonances• Di-jet resonances predicted in

beyond Standard Model theories• Masses up to 1.2 TeV studied• Tight limits set


W’

Talk of N. Skachkov


Top Quark StudiesTop Quark StudiesHeaviest known elementary particle: 173 GeV

Measure properties of the least known quark

mass, charge, decay modes, etc. data sets of 1000’s of top quarks exist

Short life time: probe bare quark Top quark cross sections

in multiple channels: top quark identification

p

p tb

W

q

q’

t b

W+

l

X

Production cross-section

Resonant production

Production kinematics

Top Spin Polarization

Top Mass W helicity

|Vtb|

Branching Ratios

Rare/ non SM Decays

Anomalous Couplings

CP violation

Top Spin

Top Charge

Top Width

_ __

_

CDF August 2009

Combination precision is 6.5%


Top Quark Mass MeasurementTop Quark Mass Measurement

DØ and CDF combined top mass result

mt = 173.11.2 GeV 0.7% accuracy

Best (of any) quark mass measurement!

• Top mass is measured using decay products in many different channels

• Lepton+jets channel with two jets coming from W is the most precise

First measurement of quark-anti quark mass difference: CPT test in

quark sector

7.38.3 tt mm GeV

16

Single Top Quark Production – 5Single Top Quark Production – 5 Observed!Observed!

EW production of top quark direct probe of |Vtb|

similar to hunt for Higgs: (Wb)b

High backgrounds

Developed and used advanced methods to separate signal

events from substantial backgrounds


Tevatron (3.2 fb-1, mt=170 GeV):

σs+t = 2.76+0.6-0.5 pb

|Vtb| > 0.77 @ 95% C.L.Talks of V. Shary, L. Dudko


Electroweak PhysicsElectroweak PhysicsIndirectly constrain new physics through precision measurements of electroweak parameters

Measure single and multi-boson production, W mass, W production asymmetry,…Leptonic decay modes of W/Z are maiunly used as hadronic modes are overwhelmed by QCD

80.401 ± 0.021(stat.) ± 0.038(syst.) GeV

Single most precise W mass measurement!

World average is now 80.399 ± 0.023 GeV

(0.025%)Statistic limited


Studies of di-boson ProductionStudies of di-boson ProductionDetect very rare SM processes, search for anomalous vector boson couplings

and develop experimental methods for Higgs hunting

• ZZ is the smallest SM di-boson cross section:(ZZ)=1.6 ± 0.1 pb

• On the road to Higgs Talk of V. Shary

H WW

2009!


b Quark Studiesb Quark StudiesHigh b quark cross section: ~10-3 tot

~104 b’s per second produced!All b containing species are produced

B, B0, Bs, Bc, b…

Large b quark data samples provide• B mesons lifetime studies• Mass spectroscopy (Bc, etc.)• Studies of Bs oscillations• CP violation studies• Search for new b hadrons• Search for rear decays

b observed! b lifetime from CDF now agrees with others

BBss Mixing Parameters Mixing Parameters

Bs meson allows to probe

the entire matrix:

Very sensitive to New Physics

P-value(SM)=3.4%

Mass difference between mass eigenstates

20

Hint of physics beyond Standard Model?!

Talk of N. Skachkov



Search for New PhenomenaSearch for New PhenomenaOne of the most natural studies is to look for New Phenomena at energy frontier machine: SUSY, leptoquarks, Technicolor, new exotic particles, extra dimensions…

Recipe: search for irregularities in effective mass spectra or otherkinematic parameters looking for events not described by the SM

A. Popov talk

Z’ decays to electron pair search

SUSY

WZ resonances search

““Ghost” MuonsGhost” MuonsIn November 2008 CDF reports observation of excess of di-muons

with large decay distances

• DØ Ø has substantially thicker muon system and magnetized iron toroid– Punchthrough is much less

• Excellent time resolution of trigger counters in all layers of the muon system– Rejection of cosmic muons


~20% excess observedNew Physics?!

CDF Preliminary

• DØ repeated similar study in March Ø repeated similar study in March 20092009• No excess found within ~1% No excess found within ~1%

uncertaintyuncertainty

• Two lessons• Importance of two

experiments• Time scale to perform new

analysis could be ~4 months


Standard Model Higgs SearchStandard Model Higgs Search

Tevatron provides:

Precision mtop and Mw measurements

Direct searches

LEP

Available experimental limits

Direct searches at LEP: MH >114 GeV at 95% C.L.

Precision EW fits

Light Higgs favored – in the Tevatron energy range!

MH 157 GeV (95%) or <185 GeV with direct LEP limit


SM Higgs Production and Decays at the SM Higgs Production and Decays at the TevatronTevatron

Production cross sections in the 1 pb range for gg H in the 0.1 pb range for associated vector boson production

Decays bb for MH < 130 GeV WW for MH > 130 GeV

Search strategy: MH <130 GeV associated production and bb decay W(Z)H l(ll/) bb

Backgrounds: top, Wbb, Zbb… MH >130 GeV gg H production with decay to WW

Backgrounds: electroweak WW production…

Major Experimental ChallengesMajor Experimental ChallengesLow cross sections and high backgrounds

• Inclusive production– at 115 GeV ~5 inclusive Higgs

bosons would be produced per day– QCD backgrounds too high…


Cross section x BR for key Higgs modes

Required - highest acceptance, use of modern analysis tools


SM Higgs Search: WH SM Higgs Search: WH l lbb (Mbb (MHH<130 <130 GeV)GeV)

• One of the most sensitive channels in the ~110-130 GeV mass range

• Consider 8 independent channels• e+jets, +jets• 2, 3 jets• 1, 2 b-tags (NN-based)

• Main background: W+b/c jets, tt• Dijet mass multivariate

discriminantLimits are used for DØØ combinationTalk of I. Razumov


SM Higgs Search: H SM Higgs Search: H WW WW l lll(M(MHH >130 >130 GeV)GeV)

Search strategy: 2 high Pt leptons and missing Et

WW pair comes from spin 0 Higgs:

leptons prefer to point in the same directionW+ e+

W- e-

n

H

Setting Limits on Standard Model Setting Limits on Standard Model HiggsHiggs

Using Neural Network plots limits on Higgs cross section set in each individual channel and normalized to Standard Model

Higgs cross section at a given mass


Limit at 165 GeV : 1.36 (expected) and 1.55(observed)

H WW

Combining Multiple ChannelsCombining Multiple Channels

Similarly, DØ uses 58 sub-channels



Standard Model Higgs SearchStandard Model Higgs SearchCombining multiple search channels Tevatron sets Standard Model

Higgs limits

Ratio to SM observed(expected): 2.70 (1.78) at 115 GeV, 0.94 (0.89) at 165 GeV

When ratio equals to one – specific Higgs mass is excluded at 95% CL


Confidence Level Combined PlotConfidence Level Combined Plot

Tevatron demonstrated sensitivity to Higgs and will continue to increase exclusion region or… find the Higgs

• SM Higgs excluded in the range 163-166 GeV at 95% CL• Expected exclusion range 159-168 GeV

Future Accelerator ScheduleFuture Accelerator Schedule


Tevatron Luminosity Tevatron Luminosity ProjectionsProjections

• Projections are based on extrapolations of the current performance

• Improvements are still coming• We expect 12 fb-1 delivered by 2011• Excellent physics program

• Many studies are statistically limited


With data accumulated by the end of 2011

95% exclusion over entire allowed mass range

Tevatron SM Higgs Exclusion

Tevatron Standard Model Higgs Tevatron Standard Model Higgs ProjectionsProjections

Dmitri Denisov, RAS, November 2009 34Good chance with 2011 data to see Hints of the Higgs boson!

Progress with SM Higgs limits at the Progress with SM Higgs limits at the TevatronTevatron


Steady progress with increase in data set and analysis experienceFactor of 1.78 from SM prediction at Higgs mass 115 GeV

Tevatron Reach ProjectionsTevatron Reach Projections


D0 Run 2 (e)

• 15 MeV error on W boson mass and no changes in mean value means SM Higgs exclusion of MH <117 GeV!

W Boson Mass

10 fb-110 pb-

1

Many other exciting studies progressing!

Russian Groups Participation Russian Groups Participation at the at the TevatronTevatron

JINR, IHEP, ITEP, MSU, PNPI – 10% of the DØ Collaboration

• Muon system design, construction and operation: IHEP, JINR, PNPI, ITEP

• Silicon detector: MSU• Key contributions to physics analysis

in– B-physics– Top quark studies– New Phenomena searches

Talks later today!


Without contributions from Russian groups

none of the results presented in this talk would be possible


Tevatron Physics Highlights: Tevatron Physics Highlights: SummarySummary

Experiments are collecting and analyzing data from the energy frontier collider smoothly Many discoveries and precision measurements~200+ studies in progress publishing 2 papers a week

Tevatron is performing extremely well: 12 fb-1 by 2011

SM Higgs search is in a very active stage Excluded at 95% CL Higgs with mass around 165 GeV Proceeding to exclude wider mass range or… to see the Higgs!

No significant deviations from the Standard Model observed… yet Although there are a few “~2 sigma” discrepancies… Data samples analyzed are to increase by 2-10 times

Looking with excitement forward for continuing exciting physics results from the Tevatron

experiments!

DØ Publications per year

Many legacy measurements in progress Precision electroweak and other sectors Will be in the text books for a while!

Some results from ppbar collider are unique

Comparing March and November 2009 Comparing March and November 2009 ResultsResults


Russian Groups Participation in Russian Groups Participation in CDFCDF

JINR and ITEP

Major JINR’s contributions• Creation and maintenance

of the scintillation complex for CDF -trigger for c,b,t – physics study

• Creation and maintenance of the Silicon Vertex Trigger for secondary vertex detection

• Top mass analysis • Search for the Very High

Multiplicity processes using CDF data


Excellent contributions!

CDF


CDF and CDF and DDØØ Experiments in Experiments in Run IIRun II

Silicon DetectorCentral Drift ChamberCalorimetryExtended muon coverageFast electronics

Silicon Detector2 T solenoid and central fiber trackerLarge coverage muon systemFast electronics

Driven by physics goals detectors are becoming “similar”: silicon, central magnetic field, hermetic calorimetry and muon systems

CDF DØØ

CDF

42

DDØ DetectorØ Detector

5 barrel layers, 800k channels

Silicon Detector

Fiber Tracker

8 axial, 8 stereo fibers double layers - 77,000 fibers with VLPC readout

scintillators

shielding

Muon System Uranium Liquid Ar Calorimeter

All detectors are running very well!

12 fb-1 capable!


Search for New Physics in Top Quark Search for New Physics in Top Quark SectorSector

• In the Standard Model top decays before hadronization

• Theories beyond Standard Model predict existence of resonances

– In top-colour assisted technicolour leptophobic heavy boson couples mainly to 3rd generation

• Search for narrow resonance optimised at high masses

– Using reconstructed 4-momenta of two top quarks

Heavy t’ quark search in the top samples in t’t’WqWq

Dmitri Denisov, RAS, November 2009 43CLGeVmt %95@311'

Lepton + jets

Excess?!

Documents

Tevatron Results and Future Prospects