The Top Quark Beyond The Top Quark Beyond the SM at ATLASthe SM at ATLAS
Granada 29Granada 29thth June 2006 June 2006
António António OnofreOnofreLIP / UCPLIP / UCP
Universidad de GranadaUniversidad de GranadaDepartamento de Física Departamento de Física Teórica y del Cosmos Teórica y del Cosmos
OutlineOutlineI)I) What do we know about What do we know about
the the top quark?top quark?
II)II) The top quark at ATLAS The top quark at ATLAS
III)III) Conclusions Conclusions
GranadaGranada, 29, 29thth June 2006 June 2006
I) What do we know about the top I) What do we know about the top quark?quark?
Nν = 2.9841±0.0083
The top quark completes the 3 family The top quark completes the 3 family structure of the SMstructure of the SM
It has spin=1/2,It has spin=1/2, Charge=+2/3,Charge=+2/3, It´s the weak-isospin partner of the b-It´s the weak-isospin partner of the b-
quark,quark, =1.42GeV (including m=1.42GeV (including mbb,M,MWW,,ss,EW corr.),EW corr.) It’s a massive particle (special role in It’s a massive particle (special role in
SM?)SM?)
From the SM we know From the SM we know that:that:
QCD-1=(100MeV)-1=10-23s
Mt => t<10-23sHadronization time
NO top hadrons
GranadaGranada, 29, 29thth June 2006 June 2006
From From ee++e, ee, e±±p and ppp and pp Colliders we have top Colliders we have top quark dataquark data
--
LEPLEPALEPH, DELPHI,ALEPH, DELPHI,
OPAL and L3OPAL and L3
(e(e++ee- -
Collider)Collider)
HERAHERAH1 and ZEUS H1 and ZEUS
(e(e±±p Collider)p Collider)
TEVATRONTEVATROND0 and CDFD0 and CDF
(pp Collider)(pp Collider)--
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
Beyond SM
Beyond SM
SM+Beyond
The TEVATRONThe TEVATRON
The present experimental knowledge on top quark physics is dominated by the TEVATRON data
•Run I (1992-1996)s = 1.8 TeVDiscover top quark in 1995Integrated luminosity 120pb-1
•Run II (2001-present)s = 1.96 TeVTotal Int.Luminosity Delivered: ~1.5fb-
1/expRecorded ~1.2fb-1/expFutur: ~2fb-1 (by 2006) ~4fb-1 (by 2007) ~8fb-1 (by 2009)•2 multi-purpose detectorsD and CDF
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
A) The top mass (TEVATRON,LEP,SLD)A) The top mass (TEVATRON,LEP,SLD) I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
measuredinferred
A) The top mass at RUN II (TEVATRON)A) The top mass at RUN II (TEVATRON)Summary of Top Mass Results
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006 mmtt=172.5±2.3 GeV/c=172.5±2.3 GeV/c22
q
q
t
t ~85%
t
t
g
g~15%
Diagrams: Dependence with Energy:
B) The pp tt cross section (TEVATRON) B) The pp tt cross section (TEVATRON)
(pp tt)@NLL=6.7pb (15% uncertainty) at Mt=175GeV
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
Top quarks are rare events: 1 in 10Top quarks are rare events: 1 in 101010 events !!!events !!!
CDF Run 2 Preliminary:
D0 RUN 2 Preliminary:
B) The pp tt cross section (TEVATRON) B) The pp tt cross section (TEVATRON) I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
C) The t bW decay and W polarizationC) The t bW decay and W polarization
t
W0 Longitudinal fraction F0
W
b
+1/2
+1/2
0
W- Left-Handed fraction F-
tb
W
+1/2
-1/2
+1
W+ Right-Handed fraction F+
tW
b
+1/2+1
-1/2V-A SUPPRESSED
W boson has three helicity states:
“Left-handed”, “Longitudinal”, “Right-handed”
Top quark decay is the most significant source of Longitudinal Ws.
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
By measuring the fraction of longitudinal Ws we are:
Testing a Standard Model prediction: F0=0.7 F-=0.3 Probing the structure of the tWb vertex
C) The t bW decay and W polarizationC) The t bW decay and W polarization
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
W(cos*)=F 3 (1-cos*)2 + F 3 (1-cos2*) + F 3 (1+cos*)2 848
- +0
D) Top Rare decaysD) Top Rare decays The top quark almost always decays to a b quark, B(tWb)~1 Most of the SM rare decays of the top are really rare
B(tWs)<0.18%, B(tWd)<0.02%
The Ratio of Events with b-tagged and no b-tagged jets is: R=B(tWb)/B(tWq) = |Vtb|2 / (|Vtd|2 + |Vts|2 + |Vtb|2) =99.8%
FCNC Decays: B(t c) +B(t u)<3.2% at 95% CLB(t Zc) +B(t Zu)<33% at 95% CL
I) What do we know about the top I) What do we know about the top quark?quark?
GranadaGranada, 29, 29thth June 2006 June 2006
A) The Most Exciting Discoveries are the Unexpected OnesA) The Most Exciting Discoveries are the Unexpected Ones Unfortunately it Seems Difficult To Predict the Unexpected…Unfortunately it Seems Difficult To Predict the Unexpected…
Why Going Beyond the SM?Why Going Beyond the SM?
B) Physics Beyond the SM Required for UnificationB) Physics Beyond the SM Required for Unification SuperSymetry at TeV scale modifies evolution of couplingsSuperSymetry at TeV scale modifies evolution of couplings Unification and Agreement with DataUnification and Agreement with Data
GranadaGranada, 29, 29thth June 2006 June 2006
II) The top quark at ATLASII) The top quark at ATLAS
C) New Physics is also a test of the SM…C) New Physics is also a test of the SM… It is mandatory to measure the top quark quantum numbersIt is mandatory to measure the top quark quantum numbers
ATLAS at CERNATLAS at CERN
Geneve Airport
LHC
CERN
SPS Accelerator
CERN (Prevessin) 27 km
ATLAS, CMS, LHCb e ALICE
20 Member States + USA, Canada, Japan, Russia, China, India, ...
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
• Proton-Proton Collisions Ecm = 7000 + 7000 GeV• 800 million collisions/s• The biggest cryogenic system in
the world (1.8K, superfluide helium)
• 27 km of magnets with B=8T
II) The top quark at ATLASII) The top quark at ATLASATLAS at CERNATLAS at CERN
GranadaGranada, 29, 29thth June 2006 June 2006
σ(W→lν)
σ(tt)mt=175 GeV
(pp tt):
q
q
t
t 10%
t
t
g
g 90%
High Collision Rate LHC (Tevatron) – every 25ns (396ns)
High Cross-Sections ~0.1b 2-3 interactions per collision
• LHC low/high lumi L=1033cm-2s-1
20 interactions per collision• LHC design/high lumi L=1034cm-2s-1
W, Z, top are rare events Requires High Luminosity Trigger is crucial: sel. Leptons High pT
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
Cross-sections at the LHCCross-sections at the LHC
e-e (1/81)
mu-mu (1/81)
tau-tau (1/81)
e -mu (2/81)
e -tau (2/81)
mu-tau (2/81)
e+jets (12/81)
mu+jets(12/81)
tau+jets(12/81)
jets (36/81)
pp tt bbWpp tt bbW++WW-- (833pb) (833pb)
• 1 Lepton pT>20 GeV, |η|<2.5• ET>20 GeV• ≥ 4 jets ET>40 GeV, |η|<2.5• ≥ 2 b-tags
Signal: tt bbqq´Signal: tt bbqq´llll++ (l=e,(l=e,))
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
A) The top mass at ATLASA) The top mass at ATLAS
proton beam proton beam
W bt
qq|
Jet
Jet Jet (b)
Jet (b)
Semileptonic TopologySemileptonic Topology
neutrino
e,
MMtt(had)(had)MMWW(had)(had)
Selected 87000 events for 10fbSelected 87000 events for 10fb-1-1 (S/B~78) (S/B~78)
Most Important Systematic Errors: Most Important Systematic Errors: Energy Jet Calibration Energy Jet Calibration FSR FSR
Systematic Errors:Systematic Errors:
SN-ATLAS-2004-040
Tot(sys) = 1.3 GeVTot(stat) = 0.1 GeV
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
A) The top mass at ATLASA) The top mass at ATLAS
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
Angular Asymmetries:Angular Asymmetries: AAFBFB, , AA++ andand AA--
AAFBFBAA++
AA--
cos(cos(ll*)*)
AAFB FB [t=0] [t=0] AA±± [t= (2[t= (22/32/3-1)]-1)]±±
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
MMt-lept-lepMMt-hadt-had
LogLog1010(L(Lss//LLBB))Sig.Sig.
BacKBacK..
L=10fbL=10fb-1-1
Pre-Selection (Probabilistic):Pre-Selection (Probabilistic): 1 lepton pT>25GeV,|1 lepton pT>25GeV,||<2.5|<2.5 4 jets, pT>20GeV4 jets, pT>20GeV,|,||<2.5|<2.5 2 b-tag jets2 b-tag jets Missing pTMissing pT>20GeV>20GeVFinal Selection: Final Selection: LogLog1010(L(Lss/L/LBB) > -0.2) > -0.2
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
The measured Angular Distributions are affected by detector The measured Angular Distributions are affected by detector related effects (resolutions, triggers, selection criteria, etc.) related effects (resolutions, triggers, selection criteria, etc.)
To recover the “To recover the “TrueTrue” signal ” signal (S)(S) Angular Distributions, Angular Distributions, reference MC samples for signal reference MC samples for signal (S(Srefref)) and back. and back. (B(Brefref)) were were generated to estimate the expected Correction Function used to generated to estimate the expected Correction Function used to compensate for experimental effects (compensate for experimental effects (ffCC=G/S=G/Srefref););
The signal is extracted from “The signal is extracted from “DataData” ” (S(S00+B+B00)) by: by: S = S = (S(S0 0 + B+ B0 0 - B- Brefref) ) xx G/SG/Srefref
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
L=10fbL=10fb-1-1
SM (LO): SM (LO): AAFBFB = -0.2226= -0.2226AA++ = 0.5482= 0.5482AA-- = -0.8397= -0.8397
/A/AFBFB = 6.0%= 6.0%/A/A++ = 1.9%= 1.9%/A/A-- = 0.4%= 0.4%
Systematic Errors:Systematic Errors:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
The dependence of AThe dependence of AFBFB on the Anomalous Couplingson the Anomalous Couplings
The b-quark mass must be taken into account The b-quark mass must be taken into account (differences up to 17% in g(differences up to 17% in gLL and 9% in V and 9% in VRR))
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay1) Anomalous Couplings with W 1) Anomalous Couplings with W polarization:polarization:
2) The helicity fractions are related to A2) The helicity fractions are related to AFBFB, A, A++ and and AA--::
SM(LOSM(LO):):
3) Best Results:3) Best Results:
(careful with definitions when comparing to (careful with definitions when comparing to TEVATRON)TEVATRON)
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Anomalous Couplings in the tB) Anomalous Couplings in the tbW decaybW decay
Best 1Best 1 Results: Results:
Working Going on…Working Going on…
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Highly Suppressed in the SM:Highly Suppressed in the SM:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Probabilistic Type Probabilistic Type of Analysis after Pre-of Analysis after Pre-selectionselection
Pre-Selection:Pre-Selection:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Specific Criteria:Specific Criteria:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Specific Criteria:Specific Criteria:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Specific Criteria:Specific Criteria:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
A) ATLAS Sensitivity (5A) ATLAS Sensitivity (5):):
B) Absence of Signal (95% C.L.):B) Absence of Signal (95% C.L.):
C) Dominant Systematic Errors: MC) Dominant Systematic Errors: Mtt e e b-tagb-tag < < 20%20%
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Combined Combined Plot:Plot:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
C) Top Quark FCNC decays (tt events)C) Top Quark FCNC decays (tt events)
Conclusions Conclusions
There is no doubt that colliders are doing There is no doubt that colliders are doing a Great Job up to now…a Great Job up to now…
Wait for the next data at the LHC...Wait for the next data at the LHC...
Many analysis are under preparation for Many analysis are under preparation for the LHC and a strong collaboration the LHC and a strong collaboration between Theoreticians and between Theoreticians and Experimentalists is necessaryExperimentalists is necessary
The Top Quark Physics is one of the best The Top Quark Physics is one of the best places to look for New Physics (at least it places to look for New Physics (at least it is there…)is there…)
The best way to access the The best way to access the top spin top spin is is to study de angular distribution of its to study de angular distribution of its decay products:decay products:
ii = analysing power of = analysing power of particle iparticle i Spin Correlations in pp tt:Spin Correlations in pp tt:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Top spin correlations (asymmetries)B) Top spin correlations (asymmetries)
X=l
X
X
SMC(LO)
C(NLO)0.3190.326
Double Differential Distributions:Double Differential Distributions:
Opening Angle Distributions:Opening Angle Distributions:
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
SMD(LO)
D(NLO)-0.217-0.237
SM Predictions:SM Predictions:
l+,t
l,q
t
q
l+,t
lqq
t
Asymmetries Definitions:Asymmetries Definitions:
B) Top spin correlations (asymmetries)B) Top spin correlations (asymmetries)
We have considered: We have considered: Alj , Ãlj , Aj
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Top spin correlations B) Top spin correlations (asymmetries)(asymmetries)
Alj
Aj
Ãlj
L=10fbL=10fb-1-1
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
B) Top spin correlations (asymmetries)B) Top spin correlations (asymmetries)Systematic Errors Systematic Errors (probabilistic):(probabilistic):
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
E) Top Quark FCNC decays (Single top E) Top Quark FCNC decays (Single top Events)Events)
A) Diagrams For Single top A) Diagrams For Single top production:production:
B) Decays under study:B) Decays under study:
ee
A)A)
B)B)
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
E) Top Quark FCNC decays (Single top E) Top Quark FCNC decays (Single top Events)Events)
A) ATLAS Sensitivity (5A) ATLAS Sensitivity (5):):
B) Absence of Signal (95% C.L.):B) Absence of Signal (95% C.L.):
II) The top quark at ATLASII) The top quark at ATLAS
GranadaGranada, 29, 29thth June 2006 June 2006
E) Top Quark FCNC decays (Single top E) Top Quark FCNC decays (Single top Events)Events)
New InteractionsNew InteractionsQuark Radius at Quark Radius at CollidersColliders
HERA (H1)HERA (H1) Results Interpreted in terms of ffqq(Q(Q22))
Result:Result: R<1.7x10 R<1.7x10--
1616cmcm
q-form factor:q-form factor:
dd/dQ/dQ2 2 = d= dSMSM/dQ/dQ2 2 x x ffqq(Q(Q22))
TevatronTevatron ((CDF, DY CDF, DY ee++ee--,,++--)) Result:Result: R<1.0x10R<1.0x10-16-16cmcm
ffqq(Q(Q22)=1-)=1- 1 1 <R<R22>Q>Q22
66
In SM (mIn SM (mtt=175GeV/c=175GeV/c22))BB((ttcc) ) ~ 5.2x10 5.2x10 -13 -13
BB((ttZZcc) ) ~ 1.5x10 1.5x10 -13 -13
SM extensions lead to large SM extensions lead to large enhancements:enhancements:1).1). 2HDM 2HDM ggijij (m (mqiqimmqjqj))2). k2). k, k, kZZ
CDF searched for: CDF searched for: ttc(u)c(u)and and ttZc(u)Zc(u)
BBttccBBttuu< 3,2%< 3,2%BBttccBBttuu< <
33%33%
CDF CDF kk22<<0.176 0.176
kk22ZZ<0.533<0.533 at at ==mmtt
At LEPAt LEP
kkZ are are
Anomalous CouplingsAnomalous Couplings
c(u)c(u)
tt
e-e-
e+e+ Z,Z, kk, k, kZZ
Top Quark and FCNCTop Quark and FCNC At eAt e++ee--, pp Colliders, pp Colliders
__
DELPHI, OPAL, L3, ALEPHDELPHI, OPAL, L3, ALEPHsearched at LEP for searched at LEP for ee++ee- - tc(u) tc(u) bWc(u) bWc(u)
Hadronic:Hadronic: WWqq´qq´ Leptonic:Leptonic: WWll±±
Top Quark and FCNCTop Quark and FCNC At eAt e++ee--, pp Colliders, pp Colliders
__
s(GeV)
Lumi.(pb- 1) Had. Lep.
95%(pb)
DELPHIOPAL
L3ALEPH
192- 202189189
189- 202
233172176411
YYYy
Y-yy
0.320.390.200.72