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The Top Quark Yesterday and Today. Hugh Montgomery Jefferson Lab IRFU-CEA Saclay February 4, 2010. Outline. Why do we need the top quark? A virtual life Observation of the Top Quark Properties of the Top Quark Electroweak Coupling of the Top Quark The Top Quark and the Future.

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The top quark yesterday and today

The Top Quark Yesterday and Today

Hugh Montgomery

Jefferson Lab

IRFU-CEA Saclay

February 4, 2010


Outline
Outline

Why do we need the top quark?

A virtual life

Observation of the Top Quark

Properties of the Top Quark

Electroweak Coupling of the Top Quark

The Top Quark and the Future



Elementary particle physics1
Elementary Particle Physics

Fermicentric Dates

Major Discoveries

  • b quark 1977

  • t quark 1995

  • nt(tau neutrino) 2000

    Critical measurements

  • t and W mass 1998

  • proton structure 1984-95 using neutrinos and muons

  • QCD at highest 1988-now energies


Upsilon discovery 1977
Upsilon Discovery- 1977

bound state of bottom quarks


The virtual life of the top quark
The Virtual Life of the Top Quark

10


Premature single top production
Premature Single Top Production

Schwienhorst – Fermilab W&C 4/1/2005


An ephemeral existence
An ephemeral existence

UA1 at the SppS

1984:

–Using isolated high transverse momentum lepton

–2 or 3 hadron jets

–Observed 5 events (e+ >=2 jets); 4 events (μ+ >=2 jets)

–Expected background: 0.2 events

•fake leptons dominate

•bb & cc production negligible

–Conclude: results consistent with M top = 40 ±10 GeV

1988:

–x6 the data

– much better understanding of backgrounds

– M top > 44

Yagil – Top Turns Ten


For a top mass less than the w mass ua2 88 89 was competitive with cdf
For a top mass less than the W mass UA2 (88/89) was competitive with CDF

Yagil – Top Turns Ten


Mass predictions and limits
Mass Predictions and Limits competitive with CDF

Quigg, Langacker


Fermilab antiprotons
Fermilab Antiprotons competitive with CDF


Tevatron run i and top

57pb competitive with CDF

19pb

Tevatron Run I and Top

Dec 94

Aug 93

Yagil – Top Turns Ten


Cdf the experiment
CDF - The Experiment competitive with CDF


Urgency

D0 competitive with CDF

CDF

Urgency

Glenzinski – Top Turns Ten


Dzero
DZero competitive with CDF


A first hint for cdf
A First Hint for CDF competitive with CDF

Yagil – Top Turns Ten


A dzero top quark
A DZero Top Quark? competitive with CDF


Profile of the top quark
Profile of the Top Quark competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


Top production and decay
Top Production and decay competitive with CDF

DIL - both W decay to leptons

Low rate, Very clean

SVX - one of the b-jets is identified using a displaced vertex tag

SVX detector

SLT - one of the b-jets is identified using a leptonic decay product

lepton I.D. in jets

Yagil – Top Turns Ten


Dilepton observations 1995
Dilepton Observations 1995 competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


Single lepton jets
Single Lepton & Jets competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


Discovery observation
Discovery : Observation competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


List of Institutions on Dzero at time of discovery competitive with CDF

(Grannis), Hadley – Top Turns Ten


Dzero Author List competitive with CDF

Abachi to Zylberstejn

Thanks to all

(Grannis), Hadley – Top Turns Ten


Top mass
Top Mass competitive with CDF


Constraints observables
Constraints/Observables competitive with CDF

  • 18 fermion 3-vector components

  • Use constraints

    • W mass (twice) (2)

    • Mass of top = mass of antitop (1)

    • Assume mass for top

    • Fit using measurement errors

  • Measure 1 lepton(3) and 4 jets (12) and Missing Transverse Energy (2)

    • 20 constraints plus measurements (20-18 2C)

  • Measure 2 leptons(6) and 2 jets (6) and Missing Transverse Energy (2)

    • 17 constraints plus measurements (17-18 -1C)

  • Further constraints

    • The parton distributions (poor man’s beam energy)

    • Internal characteristics

    • Full matrix element


Top mass methodologies
Top Mass: Methodologies competitive with CDF

  • Choose any characteristic of the event which is related to the top mass

    • Lepton transverse momentum

    • B quark decay length

    • Mass reconstructed by constrained fit

      • To lepton plus jets events (2C)

        • using just kinematics

        • Using full matrix element

        • Reducing combinations with b tagging

      • To dilepton events (<~0C!!!)

        • using all the approaches above

      • To All jets events

        • Using all the different approaches above

    • WITH (IN)Efficiencies properly treated!!

      • Lots of MC studies

    • WITH BACKGROUNDS properly treated!!


The mass of the top quark
The Mass of the Top Quark competitive with CDF

CDF 1994

CDF measured:

1994 Mtop = 174 +- 10 +- 13 GeV

1995 Mtop = 176 +- 8 +- 10 GeV

Yagil – Top Turns Ten


Top mass1
Top Mass competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


D0 run i full matrix element
D0 Run I – Full Matrix Element competitive with CDF

For each event estimate probability for a top mass value using all measured quantities compared to distribution of t-tbar production matrix element.

(Need to integrate over measurement resolutions)


Contemporary top mass
Contemporary Top Mass competitive with CDF

Tevatron (Winter 09):

mt=173.1 ± 0.6 (stat) ± 1.1 (syst) GeV

mt=173.1 ± 1.3 (stat+syst) GeV

CDF (4.3 fb-1):

mt(l+j)=172.6±0.9(stat)±0.7(JES) ±1.1(syst)GeV

Single Experiment Uncertainty

~1 GeV!!!!

FlorenciaCanelli, LP2009


Implications of the top quark mass
Implications of the Top Quark Mass competitive with CDF

The total width of the top quark is 1- 1.5 GeV

( proportional to m3 )

The top quark decays in 0.5 * 10-24 seconds

Before it can form a hadron

No top mesons

No toponium

No hadronisation

Hadronisation does not modify the spin orientation

The observed mass is that of the quark

The top quark is our only bare quark!


Luminosity helps
Luminosity Helps competitive with CDF

FlorenciaCanelli, LP2009


Top quark pair production cross section
Top Quark Pair Production Cross Section competitive with CDF

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift


Top quark pair production cross section1
Top Quark Pair Production Cross Section competitive with CDF

6% precision!

~ 6% Precision

FlorenciaCanelli, LP2009


Ttbar production spectra
ttbar production spectra competitive with CDF

Grannis– The Antitop Quark at the Antiproton celebration, LBL


Ttbar production
ttbar competitive with CDF Production


Single top production
Single Top Production competitive with CDF

Schwienhorst – Fermilab W&C 4/1/2005


Single top production1
Single Top Production competitive with CDF

Tevatron (3.2 fb-1):

st=2.76 +0.58 -0.47 (stat+syst) pb

Tevatron (3.2 fb-1), PRD66 054024, 2002:

|Vtb|=0.91 ± 0.08 (stat+syst)

FlorenciaCanelli, LP2009


Top quark properties
Top Quark Properties competitive with CDF


Top quark properties1
Top Quark Properties competitive with CDF

FlorenciaCanelli, LP2009


Top quark decays
Top Quark Decays competitive with CDF

R = B(tWb)/B(tWq)

Related to Vtb

Determined from the relative numbers of 0, 1 and, 2 b quark tags

D0 Result (CDF similar)

R = 1.03+/-0.19/0.17

Vtb >~ 0.8

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift

Buescher- D0 Report to PAC, December 2005


Top quark decays1
Top Quark Decays competitive with CDF

t  H+b?

Different possible decays of the H+

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift


W helicity in top decay
W-Helicity in top Decay competitive with CDF

Correlations between the lepton and b jet direction in the W rest frame.

lepton pT spectrum depends on W helicity

Effective mass of lepton and b jet

Fit to full matrix element

κ = N(↑↑) + N(↓↓) − N(↑↓) − N(↑↓)

N(↑↑) + N(↓↓) + N(↑↓) + N(↑↓)

Grannis– The Antitop Quark at the Antiproton celebration, LBL

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift


Top antitop spin correlations
Top- competitive with CDFantitop spin correlations

κ = N(↑↑) + N(↓↓) − N(↑↓) − N(↑↓)SM predicts κ = 0.78

N(↑↑) + N(↓↓) + N(↑↓) + N(↑↓)

D0 (4 fb-1): κ =-0.17 +0.64 -0.53

CDF (2.8 fb-1): κ =0.32 +0.55-0.78

FlorenciaCanelli, LP2009


The charge of the top quark
The Charge of the top Quark competitive with CDF

Use jet charge algorithms to attempt to determine the b and bbar jets.

Use event fit to make associations between the W and the b jet

Construct a top charge: compare with the MC of SM and Exotic

D0 Analysis

Data favor charge 2/3, excluding 4/3 with 93.7% cl.

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift

Buescher- D0 Report to PAC, December 2005


Top quark spin
Top Quark Spin competitive with CDF

Top and anti-top spins are correlated

Analysis looks at relative orientation of the leptons in the top-antitop decays

Correct spin ½ favored

Quadt– Top Quark Physics at Hadron Colliders- Habilitationschrift

Buescher- D0 Report to PAC, December 2005


Search for cpt violation
Search for CPT Violation competitive with CDF

Release constraint on mt = mtbar, measured in lepton + jets events using

matrix element technique

D0 (1 fb-1): Dmt=3.8 ± 3.7 GeV


Electroweak relationships
Electroweak Relationships competitive with CDF

  • The top contributes as mt2 to the boson masses

  • The Higgs contributes as ln mh2 to the boson masses

http://lepewwg.web.cern.ch/LEPEWWG/


Electroweak parameters
Electroweak Parameters competitive with CDF

FlorenciaCanelli, LP2009


Future promises
Future Promises competitive with CDF

Theory

SUSY see-saw mechanisms suggest mstop lowest of SUSY masses

Higgs as a top condensate composite

Tevatron

DM <~ 1 GeV

Constraints on the Higgs

Anomalies

LHC

Signals pointing to EWSB mechanism

Vtb from single top production

Higgs – top coupling

ttg, ttZ couplings

Rare decays

ILC

DM <~ 20 MeV


Future promises1
Future Promises competitive with CDF

Standard Model Electroweak Relations

MW=(1/2)gv , MZ = (1/2) sqrt(g2+g’2)v

Mf = Lf v/sqrt(2)

Arithmetic

v = 246 GeV, v/sqrt(2) = 174 GeV

Mt ~ 173 GeV

Lt =1!!!!

Just a coincidence???


Summary
Summary competitive with CDF

The top quark was conceived more than thirty years ago.

Some of us are surprised that it is already fifteen years since we helped at its birth.

Even as born it was a giant, helping us to target the Higgs.

Top is still a big baby.

Maybe, it is very close to the Higgs.

Its next ten years promise further greatness.


Acknowledgements
Acknowledgements competitive with CDF

This talk depended almost 100% on the work of others:

The colleagues on CDF and D0 with whom I shared the experience of experimental discovery.

Juan Estrada FNAL W&C – Matrix Element work

The speakers at Top Turns Ten, October 2005: Jim Cochran, Bogdan Dobrescu, Doug Glenzinski, Nick Hadley, Paul Langacker, Aldo Menzione, MeenakshiNarain and AviYagil.

Paul Grannis: Talk at the celebration for the AntiProton.

ArnulfQuadt, whose Habilitation thesis provided one re-education on the subject and some of the figures for the talk.

FlorenciaCanelli whose summary talk at LP2009 I used for some recent plots

Giorgio Chiarelli, Rencontres de Blois, 2009

The beautiful work done by CDF and D0 collaborations during Run II when I have been an anxious spectator.

The Tevatron


Spares follow
Spares Follow competitive with CDF


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