La physique des particules et le Large Hadron Collider du CERN
Electroweak and top physics at hadron collider たなか れいさぶろう 田中 礼三郎 (...
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Transcript of Electroweak and top physics at hadron collider たなか れいさぶろう 田中 礼三郎 (...
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.