Latest result of DZero@Tevatron

韩良中国科学技术大学

Main Injector & Recycler

TevatronBooster

p p

DØDØ

p source

Batavia, Illinois Chicago

Tevatron P-Pbar @ 1.96TeV 2x1032 cm-2s-1

CDF+DØ

Tevatron ： Fermilab Proton-Antiproton Collider

2007/08/05 2L.HAN@2007威海

DØ International Collaboration

• 19 countries• 80 institutions• 650+ physicists

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The D0 Detector

Silicon Micro-vertex Tracker (SMT) - up to ||<3.0 - IP resolution ~ 10m

Central Fiber Tracker (CFT) - up to ||<1.6 - 10% at pT>40GeV

LAr+Ur EM-CAL, - e, up to |3.0

LAr+Cu HD-CAL - jet/met, up to |4.0

Muon in 1.8T Toroid - up to ||<2

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• Run 2a– Finished 03/2006– Inst. lumi up to

~1.5x1032 cm-2s-1

– Delivered ~1.6 fb-1

• Run IIb– Started 06/2006– Inst. lumi up to

~3x1032 cm-2s-1

– Delivered 3 fb-1

Run II Integrated Luminosity

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

Apr-02

Jul-02

Oct-02

Jan-03

Apr-03

Jul-03

Oct-03

Jan-04

Apr-04

Jul-04

Oct-04

Jan-05

Apr-05

Jul-05

Oct-05

Jan-06

Apr-06

Jul-06

Oct-06

Jan-07

Apr-07

Jul-07

Delivered

Recorded

19 April 2002 - 3 J une 2007

2.55

3.00

Lum

inos

ity (/

fb)

Run 2bRun 2a

Accelerator and detector performance

L.HAN@2007威海

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B physics

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B production at the Tevatron

• bb cross section orders of magnitude larger than at B-factories (4S) or Z• σ(e+e- → Z → bb) = 7nb

• σ(e+e- → Υ(4S) → bb) = 1nb

• (B+, pT 6 GeV, |y|<1@Tevatron)~4 mb

• all kinds of b hadrons produced: – Bd, Bs, Bc, B**, b, b, …

• However:– Overwhelming QCD, b-hadrons hidden in 103 larger background

• crucial for B physics program:– good vertexing & tracking– muon system w/ good coverage

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1)1(2

11)1(

)(2

11

23

2242

32

AiA

AiA

iA

VVV

VVV

VVV

tbtstd

cbcscd

ubusud

tdV

0dB0sB

0dB0sB

b

sd , b

sd ,tcu ,,tcu ,, W

W

*tdV *

tsV

tsV tdV

0dB0sB

0dB0sB

b

sd , b

sd ,

tcu ,,

tcu ,,

W W

*tdV *

tsV

tsV

Vtd determination : CP violation Unitarity in SM

(0,0) (0,1)

(,)

*

ubud

*tbtd

VV

VVarg

*cbcd

*tbtd

VV

VV

*

tbtd

*cbcd

VV

VVarg

*

cbcd

*ubud

VV

VVarg

*cbcd

*ubud

VV

VV

(0,0) (0,1)

(,)

*

ubud

*tbtd

VV

VVarg

*cbcd

*tbtd

VV

VV

*

tbtd

*cbcd

VV

VVarg

*

cbcd

*ubud

VV

VVarg

*cbcd

*ubud

VV

VV

Bd oscillation frequency 2*

d tb tdm V V QCD

Bs oscillation frequency 2*

s tb tsm V V QCD

2

s ts

d td

m V

m V

Measurement of Δms contributes to better determination of Vtd

Bs Oscillation

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/ exp(- ) / 2 [1 cos( )] 0OSC NOSsP t m t

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KKBB ss 00

sDMost Clean mode BsνμDs(φπ)

The sign of Bs flavor at decay Transverse length LT(Bs) Transverse momentum PT(Bs) ~ PT(Dsμ)

Bs candidate (invi. mass/IP of tracks from , Ds) at reco-side:

μ+

π -

K+ K-

D-

S

μ(e) B

ν

00ss BB

XReconstructed Side

Opposite-side flavor tag (OST)

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μD±X7,422±281

μDsX26,710±560

Likelihood ration optimization on S/√B

Improvement on reco-side Bs candidate

Discriminator : Helicity angle (Ds,K1)Ds IsolationpT(K1K2)m(Ds)2 of Ds Vertex Fitm(K1K2 or K1)

Dataset:

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Initial Flavor Tagging

( )T

T

p qQ

p

6.0

||

6.0||

p

qpQSV

μ+

π -

K+K-

φD-

S

ν

00ss BB

37o

B

X tagging side

μ-

Flavor discriminate variables: - muon jet charge - SV charge - event charge

( )Tev

T

p qQ

p

Uncorrelated hadronization of two b-quark in PPbar interaction

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Likelihood ration from data (B+)

Single tagging variable

Δmworld-average = 0.507 ± 0.004 ps-1

Calibrate with Bd

d>0bInitial

d<0bInitial

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OSTμ sample @ D0 (~1 fb-1)

26,710±560

OST with tagging efficiency ~20%

7,422±281

1,519±96

5,601±102

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e.g. associated

μ+

π -

K+K-

φD-

S

μ(e) B

ν

X

PV

LT(BS)

00ss BB

PT(μDS)

2

s

s

s DT

DTT

BM

ppLmx

Transverse Proper Decay Length

Visible Proper Decay Length (VPDL)

Kxct MBs

K factor for missing particles Proper Decay L

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Asymmetry Amplitude Fitting Approach cos /nos osc

snos osc

N NAsymmetry D Δm Kx c

N NA

ms>14.8ps-1@ 95% CL, deviation of 2.5 from A=0 at 19ps-1

/ exp( ) 1 cos / / 2s s

nos oscs s

B B

K Kxp D Δm Kx c

cA

c

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Log Likelihood Scan Approach

Systematic:• Resolution• K-factor variation• Br (BsDsX) • VPDL model

-- 17<ms<21 ps-1@90% CL assuming Gaussian error most probable value of 19 ps-1

-- CDF result as 17.33±0.42±0.07ps-1

PDFs:• Proper Decay L• Dilution• Mass

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μ+

π -

K+K-

φ

D-S

BS

μ+

Tagging muon

Y, cm

X, cm

Oscillated BS candidate

• Two same sign muons are detected w/ tagging legη=1.4

• MKK=1.019 GeV, MKKπ=1.94 GeV

• PT(μBs)=3.4 GeV; PT(μtag)=3.5 GeV

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CKM fit without new D0 result CKM fit with new D0 result

-- First direct double sided precise measurement on the Bs oscillation frequency

ms< 21 ps-1 @ 90% CL

-- Impact on the CKM Unitarity Triangle

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b discovery @ CDF

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Heavy Baryon spectrum

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Be able to observe:

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,

1) 4 track decay of b 2) Determine background of data/PYTHIA

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3) Signal region observation:

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b discovery @ D0

J/

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MeV 1.117.6068)(

MeV 8.80.5840)(

MeV .92.5824)(

MeV 1.87.5805)(

*

b

b

b

b

M

M

M

M

E. Jenkins, PRD 55 , R10-R12, (1997)

Signal feature

-- Mass hierarchy M(Λb)< M(b-) < M(b),

with CDF result as 5.624 < M(b) < 5.8

Ξ-b→J/ψ + Ξ-

-- 3 vertexes + 4 particles fully reconstructed

-- PV lifetime: b ~ 0.1cm, - ~ 5cm, ~ 5cm

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(syst) (stat) 0.09 0.28)/()(

) /()( 0.09 0.08 -

JBRbf

JBRbf

bb

bb

1.90.4-4.415.2

bN

0.015 0.0115.774)( bM

-- Cascade B baryon discovery:

-- Production ratio :

with signal significance

~ 5

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31

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1.3fb-1

2fb-1

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Top studies

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Production cross section

Heavy resonance decay

W helicity

Anomalous coupling

CP violationSpin

Charge

Width

Mass

Production kinematics

Polarization

Rare decays

Branching ratiosCKM :|Vtb|

Top Quark Production at Tevatron

~85% ~15%• QCD pair production

NLO = 6.7 pb (for mTop= 175 GeV)

First observed at Tevatron in 1995

EWK single-top production s-channel: NLO = 0.9 pb

t-channel: NLO = 2.0 pb

(Both for mTop= 175 GeV)

First evidence in Dec. 2006 s-channel t-channel

Other: ???X 0 t t , t t H

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• Lepton + Jets: Relatively clean with manageable backgrounds

• Dilepton: Cleanest but lowest statistics

• All Hadronic: Large branching fraction but formidable backgrounds

Br(tWb) ~ 100%

Top quark pair production xsection

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pb1.00.58.2 ±±

• Important indirect test of many top quark properties

NLO calculation: 6.8 pb with ~13% uncertainty

HT>250 GeVMissing ET>30 GeV

≥1 tight tag

Lepton + Jets Dilepton

pb6.8 1.01.29.01.1

+

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Cross section measurement

SM prediction @2TeV PPbar

NNLO ~ 6.8 ± 0.8 pb

CDF D0

• Similar experimental and theoretical uncertainty• Working on Tevatron combination

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Top mass measurement

-- Affect W boson mass at NLO -- Decide Higgs mass with W

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e-channel

3 ( ) 3 ( ) ( , ) ( ) ( ) ( )

3 6 3 4 2 1 1 1 18 17 1e T W e W t te b b e jj E x y m e m m m

• #28 in 835pb-1 with high pT unlike signed e/ + 2 jets (wo b-tagging)

• underconstrained for mt

• Hypothesized mt 4 solutions with assigned weight

P/Pbar pdf Probability

b combination resolution

maximize for the estimator of mt

per eventpeak mass

(missing information eg ISR/FSR shift)

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• M.C. templates: signal tt(13 templates in 140-230GeV) + WW(ll) + Z(tt) etc

• binned maximum likelihood fit

Peak mass

Measure jets, not partons -- Calibrate the energy scale -- Associating jet with correct parton -- Extra jets add confusion

What a theorist sees: What an experimentalist sees:

-- In-situ calibration using hadronic W decays-- Sophisticated analysis methods: matrix element, kinematic fit, etc.

Lepton + 4Jets Channel

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• Event select in 370pb-1: high pT 1l + 4j, MET>20GeV, kinematic constrianed fit

• Combined fit for 0,1,2 b-tagged jets, then event weighted for 24 possible j/ solutions

• Full kinematic information + weighted solution Likelihood

where -- ftop, fraction of signal events in sample

-- JES, jet energy calibration in situ Wqq, to reduce dominant systematic by fitting mt and JES simultaneously

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(Fit JES with maximum likelihood)

170.9±2.2(stat+JES)±1.4(syst)GeV/c2 170.5±2.4(stat+JES)±1.2(syst)GeV/c2

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-- Full Run2a large statistic sample :

Latest Tevatron Combination

170.9 ± 1.1(stat) ± 1.5(syst) GeV/c2

Run I result:4.3 GeV

uncertainty

Latest Run II result:

1.8 GeV uncertainty

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-- Exceed original Run2 expectations due to in-situ jet energy scale calibration, namely statistic works on systematic

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First measurement on single top

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-- SM : direct access to |Vtb|

-- Sensitive to NSM :

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-- Event selection

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-- Signal v.s. background :

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-- Smaller cross section -- High pT lepton + MET + 2jets(>1tag) -- Large complicated background -- Multiple analysis techniques:

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First evidence for single top production

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Single top prospects – Tevatron vs LHC

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WZ Electroweak physics

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W and Z boson production @ Tevatron

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W Mass measurement @ CDF

Isolated high pT leptons + MET :

WGRAD

RESBOS

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-- 6 fits on MC template : electron + muon, MT, lepton pT and MET

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Di-boson Production & TGC

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W production @ D0

• TGC(WW) will distort CM between W boson and incoming quark

0.9fb-1,e+

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production @ D0

• TGC(ZZ, Z) will lead to excess of high energy photon

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WZ production @ D0

• TGC(WWZ) will lead to excess of triple-lepton +MET selection

SM NLO WZ=3.68 +/- 0.34pb

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ZZ production @ D0• SM NLO ZZ~1.6pb

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Hunt Standard Model Higgs

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LEP Direct searchesmH>114 GeV @95%CL

mH<153GeV @95%CL(<189 GeV if LEP2 limit incl.)

Consistency bounds on Higgs Mass

GeVmH362680

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excluded

Product@Tevatron and Decay

Search strategy: -- MH < 135 GeV: Hbb in WH/ZH associated production (gHbb overwhelmed by QCD)

-- MH > 135 GeV: ggHWW*llvv

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High-mass Search in HWW*lvlv

e+RW+L

W- e-L

nR

Sensitive to quark generation

• Understanding on dominate background

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Low mass search

u

d

W*+

W+

H0

b

b

l+

l

H

lb

b

WH associated:

W(e,) sample >=2 jets >=1 b-tag

ZH associated:

1) Z(ee,) sample >=2 jets >=1 b-tag2) 2 b-tag + MET

j1j2

ET

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CDF + D0 combination

-- Approaching sensitivity to SM Higgs -- With peak performance of Tevatron+CDF+D0, will limit or see Higgs before LHC

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MSSM Higgs search

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Yukawa couplings in MSSM

down type couplings to CP-odd A will be enhance by large tan

MA

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A@ CDF&D0

CDF Run IIa 1fb-1

tan

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Abb@ D0

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Backup

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Measurement Best result

Charge[1] Rule out +4/3e @ 94% C. L.

(D0)

Lifetime [2] c < 53 m @ 95% C. L.

(CDF)

heavy t’ [3] Exclude [196-207] GeV @ 95% C. L.

(CDF)

resonance Mx [4] >725 GeV @ 95% C. L.

(CDF)

>680 GeV @ 95% C. L.(D0)

W helicity fR [5] 0.08±0.08±0.06

<0.24@95%CL(D0)

[5] SM V-A couplings test

Longitudinal

f0 ~ 0.70

Right-handed

f R~ 0

Left-handed

fL ~ 0.30

[1] pT weighted track in jet

[2] the lepton impact parameter of W from top

No deviation from SM observed

X ?

[4] new tt resonance in exotic

[3] 4th generation of heavy quarks

Other top quark property measurement

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Impact and prospectsProspect for RunII (CDF+D0)

Δmtop < 1.5 GeV/c2

with 2 fb-1

Run I+II

mW = 80.425 ± 0.038 GeV (LEP2)mtop = 172.7 ± 2.3 GeV (DØ+CDF)

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Combined CDF+D0

mt =172.5±2.3GeV