Electroweak and top physics at hadron collider

Electroweak and top physics at hadron collider

　　　 たなか　　 れいさぶろう

田中 礼三郎 ( 岡大理 )

References• LEP

– LEP EW working group http://lepewwg.web.cern.ch/LEPEWWG/

• Tevatron – Run II Workshop on "QCD and Weak Boson Physics"

Fermilab-Pub-00/297, Eds. U.Baur, R.K.Ellis and D.Zeppenfeld, Nov. 1999, 279p.http://www-theory.fnal.gov/people/ellis/QCDWB/QCDWB.html

– "thinkshop2" top-quark physics for RUN-II & beyond Nov.2000http://web.hep.uiuc.edu/home/kpaul/thinkshop/thinkshop_alt.html

• LHC – Workshop on Standard Model Physics (and more) at the LHC 1999

CERN 2000-004, Eds. G.Altarelli and M.L.Mangano, May 2000, 529p. http://mlm.home.cern.ch/mlm/lhc99/lhcworkshop.html

– ATLAS Detector and Physics Performance ATLAS-TDR 14/15, CERN/LHCC 99-14/15, May 1999. http://atlasinfo.cern.ch/Atlas/GROUPS/PHYSICS/TDR/access.html

Contents

I. Tevatron and LHC

Accelerator & Detector

II. Electroweak physics

LEP accelerator

lineshape, QED, WW, MW, TGC

III. Top quark physics

tt,Mtop, single-top, ttH

I. Tevatron and LHCI. Tevatron and LHC

Tevatron and LHC

• Tevatron , LHC pp colliders

Luminosity: Tevatron RUN-I 0.1 fb-1

RUN-II 2 fb-1 (FNAL officially states 15 fb-1 as goal)

LHC Low lumi(1033) 10 fb-1/year

High lumi(1034) 100 fb-1/year

[1 barn (b) = 10-24 cm-2, 1 fb = 10-15 b, 1 year sec]

pp

Accelerator Ep ECM 1- bunch crossing

luminosity

(cm-2s-1)

RUN-I (1992-1995) 900 GeV 1.8 TeV 610-7 3.5s (50kH

Z)

1.61031

RUN-II (2001-2007) 1 TeV 2 TeV 510-7 396ns/132ns 21032

LHC (2006-?) 7 TeV 14 TeV 110-8 25ns (40MHz) 1033 -1034

Fermilab

CDFD0

Tevatron

Main injector

2kmWilson Hall

Fixed Target Area

N

CDF (Collider Detector at Fermilab)

D0

SiliconMicrostripTracker (SMT)

CERN

LHC accelerator

ATLAS (A Toroidal LHC ApparatuS)Liq.Ar EM calorimeter

good e/ id, energy, ETmiss

muon spectrometer air-core troidal magnet

Bdl = 2~6Tm (4~8Tm)

inner tracking system pixel, silicon strip, TRT

2T solenoid magnet

good e/ id, b-tag

2Tesla Solenoidal Magnet設計電流値の 8400 アンペアを 2000 年 12 月 26 日午後 1 時 15 分に達成し喜びの関係者たち。

SC Quadruple MagnetLHC 加速器の衝突点でビームを絞るための超伝導四重極マグネットのプロトタイプ。長さ６メートル。日本の高エネ研で開発し東芝で製造した 16 台が LHC 加速器に組み込まれる。

TGC(Thin Gap Chamber) 製作　トリスタン冨士実験室B4

ミューオントリガーチェンバーはイスラエル・日本・中国が協力して作る。

日本は約 1000 台のチェンバーを高エネ研で量産し（写真）、神戸大学で検査してから CERN に送る。

トリガーチェンバーからの微小信号をソニーの半導体技術で作った特殊チップでデジタルに変える回路ボードの写真。 2000 年に 23,400 セットが日本で製造され中国で検査された。

Silicon Micro-strip Detector

浜松ホトニクスで製造された 6.4 cm 角のシリコン半導体検出器４枚をモジュールに組立てたもの。粒子の飛跡を高い精度で測定する。日本はこのモジュールを 690 台製造する。

日本のデザインが採用されたハイブリッド回路フレキシブル基板。

TMC(Time Memory Cell)

日本で開発中の時間測定チップの拡大写真（ 6 mm x 6 mm ）。東芝の半導体技術を使いチップあたりのトランジスター数は 44 万個。このチップは２万個をアトラスの測定器に使う。

GEANT4

オブジェクト指向のソフトウエア－技術を用いた検出器シミュレーションプログラムの開発。

CMS (Compact Muon Solenoid)

4T solenoid Compact muon spectrometer EM calorimeter PbWO4 for H

ABC at hadron collider We never know total longitudinal momentum in any event. Total transverse momentum of all particles is zero.

transverse momentum pT = |p| sin transverse energy ET = E sin pseudo-rapidity = -ln tan() missing transverse energy ET

miss = E

Distance in pseudorapidity-azimuthal angle space （ used in jet cone algorithm) R=()2 +()2

Existence of minimum bias events. LHC: inelastic, non-diffractive 70mb 23 pile-up/crossing@1034

Tevatron RUN-II: 6 pile-up/crossing (Poisson)

dN/ddistribution

• rapidity

• pseudo-rapidity = -ln tan()

cf. ATLAS detector

tracker |calorimeter |

Jinnouchi(ICEPP)

z

z

pE

pEy ln

2

1

II. Electroweak physicsII. Electroweak physics

Electroweak physics

1. Recent LEP results at LEP– lineshape

– QED

– WW(CC03) cross section

2. Electroweak physics at Tevatron/LHC– W mass

– TGC

LEP operation between 1989-2000

Great success of the Standard Model

1. Number of the light neutrino species N=3 (not ).

2. Precise prediction of Mtop=174.64.4 GeV (Osaka2000) (before discovery at Tevatron!).

3. Indication of light Higgs from EW precision data.

4. Gauge unification with SUSY at high-mass scale.

But Higgs sector is quasi-totally unknown !

LEP Experiments４　 Experiments

ALEPH (J.Steinberger)

DELPHI (U.Amaldi)

L3 (S.C.C.Ting)

OPAL (ALDO.Michelini)

LEP1(1989-1995)

Z0 resonance scan

high statistics

15 millions

2 millions

LEP2(1996-2000) above WW threshold

Main Physics Goals at LEP1 High precision test of the

Standard Model Z-lineshape, Asymmetries

Search for new particlesHiggs, SUSY

Heavy flavor physics tau, bottom, charm

QCD study

Main Physics Goals at LEP2 Gauge boson properties of the

Standard ModelW mass, TGC

Search for new particlesHiggs, SUSY

llZ

qqZ

August 2000

January 2001 ALEPH dismantling

Z line shape

Z peak datamass and width (Breit-Wigner denominator)

hadronic pole cross section

Pole leptonic asymmetry

width)dep.(s2

Z

ZZ M

isMs

220 12

Z

hadee

Zhad M

22,0

2 with

4

3

ff

ff

AV

AV

ffef

FB gg

ggAAAA

final results of

Z lineshape & AFB

at LEP!

LEP EW fit results

Number of light neutrino species

or0.06% Bhabha

3) than 2σ( 008.0984.2

312

N

th

02

lhZ

l

SM

ll RM

R

0010.00171.0

025.0767.20R

(nb)037.0540.41

)10( (GeV)0023.04952.2

)10(2.2 (GeV)0021.05187.91

,0

l

0

3-

-5

lFB

h

Z

Z

A

M

(Bayesian) .MeV@95%C.L0.2invZ

ZM

Z

dominant systematic errorMeVbeam energy calibrationnb : Bhabha cross section

LEP Fest, Oct. 2000

LEP SLDLEP SLD Np,p

QED dominant theoretical error

22)5(22

1

0

ZtopZhadZlZ MMM

M

BESII 0.04 09.0

2M-VEPP),BESII(BEPC21- ZM

Ｒｈａｄ

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

ｓ（ＧｅＶ） Pietrzyk ‘00

　　　　 　　 　　　　　　　　　　　　　　　　　　　　　　　　　

Eidelman&Jegerlehner

　 　　　　　 Davier&Höcker

MHiggs < 170 GeV@95% C.L.

　 　　　 Eidelman&Jegerlehner

　　　　 Pietrzyk

MHiggs < 210 GeV@95% C.L.

Higgs mass limit (Osaka2000)Higgs mass limit (Osaka2000)

(CC03) WWee

… not gauge invariant for off-shell W, but backgrounds are small (few per mil) in ‘tHooft-Feynman gauge.

WW production at LEP

WW Cross SectionGauge cancellation

observedZWW vertex exists

However puzzled by-3 than GENTLE at 189 GeV

(Lepton&Photon 1999)

O() CC03 Cross Section On-shell

Full 1-loop EW & W-decay … known (Böhm,Bardin)

Off-shell No complete 1-loop calculation e

xists! # of diagrams 1000 - 9000 (qq) (eeee)

Non-universal EW Radiative Corr. -1 ~ -2 % !LEP2 MC workshop(hep-ph/0005309)

DPA(Double Pole Approx.)W.Beenakker et al. Nucl.Phys.B548(1999)3

A.Denner et al. PLB475(2000)127

S.Jadach et al. PLB417(1998)326

- double expansion in O() and O()

- isolates the contributions of the poles at the

complex squared masses and projects onto

the respective gauge-invariant residues.

Expected uncertainty

Valid for

s > 2MW+nW (n=3-5) 170 GeV

%5.0)ln(

W

W

M

IBA (Improved Born Approx.)

GENTLE (D.Bardin et al.) DPA (Double Pole Approx.)

YFSWW3 (S.Jadach et al.)

RacoonWW (A.Denner et al.)

ｔｈ＝ ±0.7-0.4%(170-200GeV)

%2th

1.4%

@189GeV

LEP

Electroweak physics at Tevatron/LHC

1. EW precision measurements, MW

2. Drell-Yan process (qqWlqqZll)3. Vector-boson pair production

W+W-, W±Z, ZZ, W±, Z

4. Non-Abelian gauge-coupling, TGC/QGC

5. Gauge-boson fusion and scattering

W massLEP2 Tevatron

RUN-I RUN-IILHC NLC

35 MeV

60 MeV 30 MeV

15 MeV

10 MeV

• goal

top =2 GeV W =12 MeV

ultimate goal W =15 MeV

top(GeV)

W(GeV)

SSM

SM

• LEP average W-mass

… Systematics are dominated by

Final State Interactions (FSI).

MW=80.4270.025(stat) GeV

Dominant systematic errors

Beam Energy 17 MeV

Fragmentation 20-30 MeV

For qqqq

Color Reconnection 50 MeV

Bose-Einstein Correl. 25 MeV

MW measurement at LEP2

Final State Interactions (FSI)

• Color Reconnection QCD interconnection phenomena

- separation of W decay vertices 1/w~ 0.1fm

- Hadronization scale ~ 1fm– Observable

… consistent with 0

• Bose-Einstein Correlation Enhanced probability of

production of identical bosons

=> W mass shift !

qqlch

qqqqchch nnn 2

MW measurement at Tevatron

W transverse mass

major uncertainty source• E, p scale & resolution

• Recoil modelling

• pTW

• PDF (parton distribution)

||

)cos1(2

upp

ppmlTT

TlT

WT

MW measurement at RUN-I/LHC

Energy and momentum scale/resolutionZe+e-, Z+- , J/, (2s)

Recoil modellingneutrino PT imbalance

recoil from ISR(QCD) spectator quarks additional minimum bias

Exploit similar productionmechanism for W and Z.

Parton distribution functions (PDF)x-region of W production asymmetry u(x)>d(x)

W+(W-) boosted along p(p-bar)

use of W charge asymmetry data

to constrain PDF

such an asymmetry does not

exist at LHC(pp) !use of lepton pseudorapidity

distributions in W and Z decays constraint PDF to few %

W < 10 MeV

W production model pTW

pTW is estimated from Z data

error MW=20 MeV

• dominated by Z statistics

• theoretical error (5 MeV)

theory

ZT

WT

data

ZT

WT

dydpd

dydpd

dydp

d

dydp

d

2

2

22

• Non-Abelian SU(2)U(1) gauge theory Gauge boson self-coupling WW and WWZ Effective Lagrangian (Lorentz invariant WWV vertex) 2x7 parameters C,P-conserv, violate C&P, violate CP Hagiwara et al. Nucl.Phys.B282(1987)253

., and cot,

2

~

2

~

24

5

21

VVVWWWee, gZ, gV

VWWm

VWWVVWWig

VWWWWig

WWVm

VWWWWWWVggiL

WWWZWW

W

VVV

V

W

VV

VWWV

WWVeff

Trilinear Gauge Boson Coupling

)~

,~,(g g ,, V4

V51 VVVV

Vg

C,P-Conserving 5 Parameters (EM gauge inv. )

… all vanishing in the Standard Model (tree).

• Charge:

• W-boson Static Moments:

Magnetic Dipole

Electric Quadrupole

- At LEP, no form-factor(regualization cutoff )

- SU(2)U(1) constraints: Any theory of new physics beyond SM which includes EW as effective low energy limit may introduce deviations from SM. LEP1 data contributes via loop corrections.

2W

W m

eQ

ZZZZZ ,,,,gg 11111

1egeW

ZWZZ ,g tan21

11 g

TeV2Tevatron

)/ˆ1(

TGC

0

FF

nFFs

12

gm

e

WW

• Ｄ０ (Tevatron)W,WZ,WW

30.005.0

10.000.0

Low energy measurements(indirect limits)

limits no :,,,~

,d from limits comaprable:,~,~d fromlimit tight :

~

554

e4

n

ZZ

ZZ

ggg

sbg

Ellison&Wudka (hep-ph/9804322)

New Physics TGC<O(10-2 ~10-3) !

loop-2 toup

0d w

Ellison&Wudka (hep-ph/9804322)

TGC study at LHC

Also we need study on

Quartic Gauge-boson Coupling (QGC)

WWWWWWWWWW

couplings

Sensitivity at 95%C.L.

Luminosity 30(100) fb-1

Form factor FF=10 TeV for WWWWZ

6 TeV for ZZ

increased sensitivity by pronounced

high s^ at LHC.

ｓ

III. Top quark physicsIII. Top quark physics

Fermi National Accelerator Laboratory

November 10 - 12, 2000

1) Weak Interaction: Top decay, single top production, measurement of Vtb, etc.

2) Strong Interaction: Top pair production, spin correlation, gluon radiation, etc.

3) Tools for top: Monte Carlo event generators, analysis techniques, etc.

4) Top as a tool: Using top to search for the Higgs boson, supersymmetry, etc.

5) Non-standard top: Compositeness, non-standard couplings, top and electroweak

symmetry breaking, etc.

http://web.hep.uiuc.edu/home/kpaul/thinkshop/thinkshop_alt.html

Top quarktop quark … spin 1/2, Q= 2/3|e| fermion

colour triplet under SU(3) of strong interaction

weak-isospin partner of b-quark

None of these has been directly measured …

Fundamental questions:

• Heavy top quark … generated by Higgs mechanism?

• Top mass related to top-Higgs-Yukawa coupling?

• Top as EW symmetry breaking mechanism?

• Non-SM physics manifest in non-standard top coupling?

• Top quark mass

large top-Yukawa coupling

• Top quark width (MW, s2, EW O() corrected)

(tWb)/|Vtb|2~0.807 GeV (GFmt3/82=1.76GeV)

(top)4.6x10-25s

non-perturbative QCD hadronization

-1QCD ~ (100 MeV)-1 ~ 10-23s

top decays as free quark (no top hadrons, no toponium spectroscopy)

top decay will remember its original spin-1/2 state.

))(1(2)(y 2/13/4t ttF mG

top as a tool at LHC

Top quark physics

1. Top production cross section

2. Top mass measurement

3. Single top production

4. tt spin correlation and CP violation

5. Anomalous couplings

6. Rare decay (tWb), FCNC

7. Top quark Yukawa coupling in ttH

/

Top mass

W helicitySpin polarization, CP

Top production cross section

non-SM decays

CKM Vtb

Top decay modes

Branching ratios

top quark physics

Resonance production

Rare decays, FCNCTop Yukawa coupling

1. Top production cross section

top factory

pb800 TeV14s

pb 7 TeV2 s

NLO

NLO

tot=70mb for LHC

109 interactions/sec@1034cm2s-1

Interesting physicsW production: ~2kHz

Top production: 10Hz

Higgs production: 0.1(0.01)Hz

for MH=100(500) GeV

PDF: 　ｆ i(x1), ｆ i(x2)

xi is momentum fraction of

parton i.

• Tevatron　　 qq(90%), gg(10%) RUN-I

qq(85%), gg(15%) RUN-II

• LHC　　 qq( 5%), gg(95%) enhanced gluon structure functio

n.

LO),()()()(

^^

2

1

0 121 tijiiij

msxfxfdxdxs

sxxs 21

^

Total tt production rates at LHC

• tt cross section goal tt= 5% for mt =2GeV

12% theoretical systematic uncertainty

… mt =4GeVfrom tt

Renormalization(R) and factorization(F) scale … 6%

PDF … 10% (MRST v.s. CTEQ5M = 3%)

　 ＝ R ＝ F

1/2 ０＜ ＜ 2 ０

０ = mt for tot

０ = mt2+pT

2 for d/dx

０ = mt2+ (pT,t

2+ pT,t2)/2

for d2 /dxdy

R=F NLO NLO+NLL

resummed

mt/2 890 pb 878 pb

mt 796 pb 859 pb

2 mt 705 pb 853 pb

Tevatron RUN-I tt

NNLO-NNLL: N.Kidonakis (hep-ph/0010002)

Why greater shift than NLO syst. ?

Top quark decay

Single lepton+jet channel at LHCttWWbb(l)(jj)bb Br.~30% 　 ~2.5Mevents/10fb-1

Isolated lepton for trigger (pT>20 GeV)

Selection cuts– Lepton: pT>20 GeV, ||<2.5

– Etmiss>20 Gev

– Jets:Nj4, pT>20 GeV, ||<5, R=0.7

– b-tag jets 1

33.3% efficiency ~ 820k tt events/year

S/B(W+jets) ~ 18.6

Di-lepton channel at LHCttWWbb(l)(l)bb Br.~5% 　 ~400k events/10fb-1

Isolated lepton for trigger (pT>20 GeV)

Selection cuts– Two opposite sign leptons:

Lepton: pT>35(20) GeV, ||<2.5

– Etmiss >40Gev

– Jets:Nj 2, pT > 25 GeV, || < 5, R=0.7

– Like-flavour case (e+e-,): |mll-MZ|>10 GeV

– b-tag jets 1

~ 58k tt events/year

S/B ~ 50

Multi-jet channel at LHC

ttWWbb(jj)(jj)bb Br.~44% 　 ~3.7Mevents/10fb-1

Huge QCD multi-jet backgrounds, not-easy trigger

Tevatron: CDF simple cut + high b-tag 46% 3 signal

D0 Neural network

Selection cuts– Jets:Nj>6, pT>15 GeV, ||<3, R=0.7

– b-tag jets 2, ||<2.5

– pTjets > 200 GeV

19.3% efficiency, S/B ~ 1/57 (QCD=1.4b for pT> 100 GeV)

further improvements by W-reconstruction, tt-reconstruction

harder jet cuts pT> 25 GeV S/B~1/6

…Very difficult channel.

2. Top mass measurement

high precision measurements 　　 parametric errors　

• goal Tevatron

RUN-I RUN-II

LHC NLC( )

5.1GeV < 3 GeV < 2(1) GeV 0.2GeV

theo (had)

=0.00016

mtop=2GeV mtop=1GeV

MW/MeV 6 3.0 12 6.1

sin2effleptonx105 4 5.6 6.1 3.1

top mass definition pole mass mt

perturb. top quark propagator

mt* = mt – it/2

mass

Concept of pole mass is intrinsically

ambiguous by ~ QCD

sizeable higher order correction.

• e+e- collider … threshold scan • pp collider … invariant mass

What do we measure?

invariant mass of top quark decay system

1) experimental procedure based on LO

theoretical calculation (not sensitive to

mass renormalization at all).

2) prone to large non-perturbative

corrections of relative order QCD/mt

because loss or gain of a soft particle

M2 ~ mt QCD

Limitation in mtop measurement.

Minv of single top-quark pole mass

But experimental error > theoretical

Tevatron mtop ~ 3 GeV

LHC < 2 GeV

(problematic for l J/X < 1GeV,

non-perturbative power corr.?)

MS

%11.005.6)(

))(1/()(

tQCD

QCDtt

m

mm

GeV 10 tt mm

Tevatron RUN-I Mtop

CDF: top mass in ljjbb

• systematic errors

Systematic GeV/c2

Jet energy scale 4.4

ISR, FSR 2.6

bkg. shape spectrum 1.3

b-tag bias 0.4

PDF 0.3

MC generators 0.1

TOTAL 5.3

CDF top mass in sub-samples

b-tag is quite useful !!

b-tag• Vertex detector b-quarks have a long lifetime:

(b) ~ 1.5ps (cm)

B-tagging using displaced vertices

CDF RUN2a: b = 60% , c = 25%, j = 0.2%

RUN2b: b = 70% , c = 10%, j = 0.02%

• Soft lepton taggingidentifies lepton in semi-leptonic

b(or c) decays

leptons are softer less isolated than

from W/Z decay.

ATLAS: b = 60(50)% for low (high) lumi.

c = 10%, j = 1%

Xtt search by CDF

Top mass measurement at LHC• lepton + jet channel

1 year at LHC low lumi (10 fb-1)

mtop < 2 GeV

mtop from tl+J/+X decays (CMS)Invariant mass ml+J/is correlated to mtop

Cuts:

- Isolated lepton: pT>20GeV, ||<2.4

- 3 in jet: pT> 4GeV, ||<2.4

2 ’s have m~ mJ/

- |m ｌｌ -mZ|>10 GeV, Etmiss>40 GeV

- 2 additional jets: pT>15GeV

In 4 years at LHC high lumi (400 fb-1) ~ 4,000 events expected. stat. error < 0.5 GeV syst. error < 1 GeV

• possible extensions

- use bJ/e+e- as well.

- use jet-charge method instead

of We - other heavy particle instead of J/ ?

Limitations• Knowledge of the b-hadrons fragmentation function

B-factory Upsilon(4s) top (contributions from baryons and Bs)

• Size of non-perturbative corrections to mtop v.s. mlJ/correlation.

W-gluon fusion W* Wt-associated

total single top quark production rate ~ ½ ttbar ! (t-ch) updated with CTEQ5M1 (old CTEQ/MRS had bad b PDF) change -15%, -13%,-3%.(Z.Sullivan)

3. Single top production

Why single-top ?

Vtb provides the only known way to directly

measure Vtb at hadron collider.

2. Single top quark ~100% polarized test V-A structure of CC weak interaction

CDF RUN-IDid not observe single-top events.

• Wg (th = 1.45±0.08 pb) events observed

Wg 1.40.3, bkg 13.02.1Wg < 13.5 pb at 95%C.L.

• W* (th = 2.12±0.10 pb) events observed W* 1.20.2, bkg 31.54.7

W* < 12.9 pb at 95%C.L.

Wg

W*

W-gluon fusion

Space-like(q2<0) W

Cross section scales as 1/MW2

PDF: gluon-splitting • signal 1 b-tag, 1 forward jet

1 e/missing energy• backgrounds

W+jets, tt, Wbb, s-ch, Wt

S/B stat.

Vtb|/|Vtb|

LHC (30 fb-1) 2.4 < 1% 5%

W*

Cross section scales as 1/sParton luminosity is constrained fromDrell-Yan qqW*l• signal 2 b-tag,

1 e/missing energy• backgrounds

tt, t-ch, Wbb, W+jets, Wt

S/B stat.

Vtb|/|Vtb|

LHC (30 fb-1) 0.56 5.5% 5%

bb

Tevatron RUN-II LHC

* 4-quark generation (|Vts|=0.55, |Vtb|=0.835) T.M.P.Tait and C.-P.Yuano FCNC Z-t-c vertex (|Ztc|=1) Phys.Rev.D63(2001)014018 top-flavour model (MZ’=1 TeV, sin2=0.05)+ charged top-pion (m=250,450 GeV, tR-cR mixing~20%)

top-flavour model charged top-pion

6. Rare decay (tWb), FCNCTop decay width (tWb)/|Vtb|2~

GeV

Any non tWb is rare decay!

Next most likely SM decays

Br(tWs) 1.610-3 with |Vts|=0.04

Br(tWd) 110-4 with |Vtd|=0.01

Br(tWZb) 10-6 ~10-7

Br(tX) < 10-11 , X from FCNC

/

SM 2HDM SUSY Exotic quark

Br(tqg) 510-11 ~10-5 ~10-3 ~510-4

Br(tq) 510-13 ~10-7 ~10-5 ~10-5

Br(tqZ)

~10-13 ~10-6 ~10-4 ~10-2

FCNC top quark production

FCNC top quark decay

7. Top quark Yukawa coupling in ttH gg,qq ttH

goal: first direct measurement of

top-Yukawa couplingimportant for intermediate mass Higgs

boson (mH ~100-130GeV)

NLC s=800 GeV, MH=120 GeV

luminosity 1 ab-1 (1 atto=10-3 femto)

yt/yt = 5.5%

(A.Juste, G.Merinos, hep-ph/9910301)

ttH production cross section

No NLO calculation exists.

ttH analysis by CDF120 ttH for 15fb-1 (cf. ~100 tt at RUN-I)

irreducible backgrounds ttbb

Hbb for MH < 140 GeV (8 fermion)

jjjjbbbb(55%),ljjbbbb(38%),llbbbb(7%)

HWW for MH > 140 GeV (10 fermion)

8jbb(30%), ljbb(42%),

lljbb(22%), llljjbb(6%)

Event selection 1 isolated lepton > 15 GeV missing ET > 15 GeV

4 jets greater than 15 GeV 2 additional jets > 10 GeV (ttH) 3 high purity b-tags (reject ttjj bkg.) invariant mass of 4th highest b-pair

be greater than 60 GeV

MH ＝ 120(115) GeV, 15fb-1

~7(8) signal events

backgrounds: ~12 ttbb, ~2 ttcc

2.5 significance for b=60(70)%

exploit kinematical information !

Heavy Higgs

~ 1event of tri-leptons

~ 1-2 events for like-sign di-leptons

ttH analysis by ATLASttHWbWbbbljjbbbb

full reconstruction of 2 top quarks, irreducible ttbb background

signal significance = 3.6, yt/yt = 16% @ 30 fb-1

12% @ 30+70 fb-1 for mH=120 GeV

Summary of top quark physics

top quarkproperty RUN-I CDF

measurementRUN-I RUN-IIa RUN-IIb LHC

tt6.5+1.7-1.4 pb 25% 10% 5% 5%

Mtop176.14.25.1 GeV/c2 6.6 GeV 3 GeV < 2 GeV < 1 GeV

W helicity F0

W helicity F+

0.910.370.130.110.150.06

0.40.15

0.090.03

0.040.01

0.010.003

RBr(tWb) /Br(tWq)

0.94+0.31 -0.24

30% 4.5% 0.8% 0.2%

single top|Vtb|

< 13.5 pb-

--

20%12%

10% 5%

10% 5%

Br(tq)Br(tZq)

< 0.03 at 95% C.L.< 0.33 at 95% C.L.

0.030.30

210-3

210-2

210-4

210-3

210-5

10-4

ttHytop

- - - discovery

12%

SummarySummary

1990’s … remarkable success of the Standard ModelN top quark at 175GeV as predicted from LEP/SLDnon-Abelian nature of SU(2)U(1) with W/Z vector boson

• Higgs sector remains unexplored.

2000’s … Higgs discovery, physics beyond the Standard Model

tool: W/Z boson, top, bottom

detector key issue: vertex for b-tag, jet energy calibration.