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Testing the SM in tt and single top production. António Onofre ([email protected]). On behalf of the ATLAS+CMS Collaborations. Moscow July 26 – Au gust 2, 2006 XXXIII International Conference on High Energy Physics. 1) tt @ LHC. tt Cross section Top spin correlations - PowerPoint PPT Presentation
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António Onofre António Onofre ([email protected])([email protected])
Moscow July 26 –Moscow July 26 – AuAugust 2, 2006gust 2, 2006
XXXIII InternationalXXXIII International Conference on High Energy Conference on High Energy PhysicsPhysics
On behalf of the ATLAS+CMS Collaborations
Testing the SM in tt and Testing the SM in tt and single top productionsingle top production
OutlineOutline
2) Single top @ LHC: 2) Single top @ LHC:
3) Conclusions3) Conclusions
Production Cross sectionProduction Cross section
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
1) tt @ LHC1) tt @ LHC tt Cross sectiontt Cross section Top spin correlationsTop spin correlations Probing the Wtb vertexProbing the Wtb vertex FCNC top decaysFCNC top decays
What do we know about the top quark?What do we know about the top quark? The top quark completes the three family structure of The top quark completes the three family structure of
the SMthe SM Its massive Its massive Spin=1/2,Spin=1/2, Charge=+2/3,Charge=+2/3, Isospin=+1/2Isospin=+1/2 ttbWbW
Large Large =1.42GeV (m=1.42GeV (mbb,M,MWW,,ss,EW corr.),EW corr.)
Short lifetimeShort lifetimehad QCD-1 >> decay
“t-quarks are produced and decay as free particles”
NO top hadrons
m/m <2%
-4/3 excluded @ 94%C.L.(D0)
c<52.5m @95%C.L.(CDF)
Not directly
The TEVATRON is probing better than ever the top sector…The LHC will allow precision measurements of Top Quark
PhysicsMoscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
~100%
Not directly
1) tt @ LHC1) tt @ LHC
~ 833pb @ 14TeV
Production X-section:Production X-section:
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
2 b-jets
pT>20 GeV
pT>20 GeV
≥4 jets (R=0.4) pT>40 GeV t (had)
t (lep)
W (had)
Clean Topology: tt back to back
Used for several studies
Semileptonic Topology:Semileptonic Topology:
+(90%) (10%)
Golden Channel
tt cross tt cross sectionsection
1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
Selected 87000 signal events for L=10fb-1 (S/B~78, ~12 with back)
Although errors are dominated by systematics It seems possible to determine mt @ 1GeV level
(with L=10fb-1)
(=3.5%)
mmt (had)t (had)
Comb.
=10.6GeV
Systematic Errors:Systematic Errors:
tt cross tt cross sectionsection
1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
Syst.(dominant): btag(7%), PDF(3.4%), PileUp(3.2%)Back.(dominant):tt,W+jets= 6.3%
A) Semi-leptonic channel (ttbbqql):
tt/tt= 9.7%(syst)±0.4%(stat)±3%(lum)
L=10fb-1CERN/LHCC 2006-021
CMS TDR 8.2
B) Di-leptonic channel (ttbb llll):L=10fb-1
Syst.(dominant):PDF(5%),btag(4%),JES(4%)
Back (dominant): ttll.(W, leptons)
= 5% (S/B=5.5)
tt/tt= 11%(syst)±0.9%(stat)±3%(lum)
tt cross tt cross sectionsection
With Tau leptons (ttbb ll, hadrons):
tt/tt= 16%(syst)±1.3%(stat)±3%(lum)=2%, S/B~1, -tag=30% ]
C) Fully Hadronic channel:
tt/tt= 20%(syst)±3%(stat)±5%(lum)
L=1fb-1
=2%, S/B<1/9 (QCD) Sys: JES(11%), PileUp(10%)
Top Spin Top Spin CorrelationsCorrelations
1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
(tLtL) + (tRtR) - (tLtR) - (tRtL)
(tLtL) + (tRtR) + (tLtR) + (tRtL)A=
Testing the tt Production X-section:
l+,t
lqq
t
Other angular distributions:
AD(LO)
AD(NLO)
-0.217-0.237
SM:
A(LO)A(NLO)
0.3190.326
Although t and t are produced unpolarized their spins are correlated
New Physics affects A
X=spin analysing power of X
SM:
1 dN 1
N dcos2( 1 – ADXX´cos)=
Top Spin Top Spin CorrelationsCorrelations
1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
A) Spin correlations and angular distributions:
l,
tl,
q
t
q
B) Spin Asymmetries can also be used (X-check)
(for L=10fb-1 precision A,AD below 10% )(hep-ex/0605190, subm. to Eur.Phys.J.C)
(Eur.Phys.J.C44S2 2005 13-33)• Semileptonic + Dileptonic• Syst (Eb-jet,mtop,FSR)• ~4% precision-0.29
0.42
SMMtt<550 GeV
0.008 0.010AD
0.014 0.023A
Error (±stat ±syst)
L=10fb-1
(CERN/LHCC 2006-021, CMS TDR 8.2)
A
N(cos) -
N(cos) N(cos) +
N(cos)
= - ADXx´ 1
2Ãxx´
Probing the Wtb vertexProbing the Wtb vertex1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
A) Test the tbW decay vertexMeasure W polarization (F0, FL, FR) through lepton angular distribution in W cm system:
Semilep. +
Dileptonic
• Syst ( Eb-jet,mtop,FSR )• F0 F0 ~ 2% ; FR ~ 0.01
0.000(mb=0)
0.297
0.703
SM
0.003 0.024FL
0.003 0.012FR
0.004 0.015F0
Error (±stat ±syst) (Mt=175 GeV)
(Eur.Phys.J.C44S2 2005 13-33)
L=10fb-1
cos(l*)
(1/
)d/d
cos(
l*)
Probing the Wtb vertexProbing the Wtb vertex1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
B) Anomalous Couplings in the tbW decay
Angular Asymmetries: AFB, A+ and A-
AFBA+
A-
cos(cos(ll*)*)
AFB [t=0] A± [t= (22/3-1)]±±
SM(LO):SM(LO):
(PRD67 (2003) 014009, mb≠0)
Probing the Wtb vertexProbing the Wtb vertex1) tt @ LHC1) tt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
1 Results:
B) Anomalous Couplings in the tbW decay
SM(LO):
L=0.423R=0.0005 (mb≠0)
L=10fb-1
FCNC in top quark FCNC in top quark decaysdecays
1) tt @ LHC1) tt @ LHC
The top quark almost always decays to a b quark, B(tWb)~1
B(tWs)<0.18%, B(tWd)<0.02% (other decays are really rare) FCNC decays are highly suppressed in the SM:
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
At LHC Look for:
hep-ph/0409342APPB35(2004)2695
FCNC top FCNC top decaysdecays
1) tt @ LHC1) tt @ LHCB) In the absence of signal:B) In the absence of signal:
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
With 10 fb-1 already two orders of magnitude better than LEP/HERA/TEVATRON
A) 5A) 5 Sensitivity: Sensitivity:
L=10fb-1
L=10fb-1
ATLAS: Br(tqg@95%CL)<0.14%
Production Cross Production Cross Section Section
2) Single top @ LHC2) Single top @ LHC
Three different Processes (never observed yet)
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
[ PRD 70 (2004) 114012, PL B524 2002 283-288 ]
• Quark-gluon luminosity inside b-quark (PDF)• Renormalization scale ()• top mass (mtop=4.3GeV W*) changed by 3%)
Theoretical uncertainties:
Powerfull Probe of Vtb ( Vtb/Vtb~few% @ LHC )
t-channel Wt-channel W* (s-channel)
~ 250 pb ~70pb ~ 10 pb
VtbVtb Vtb
Vtb
Probe New Physics Differently: ex. FCNC affects more t-channel ex. W´ affects more s-channel[ PRD63 (2001) 014018 ]
Production Cross Production Cross Section Section
2) Single top @ LHC2) Single top @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
Common feature: 1 lepton, pT>25GeV/cHigh Missing ET
2 jets (at least 1 b-jet)(ATL-COM-PHYS-2006-002)
(ATL-PHYS-PUB-2006-014)
t-channel/= 8%(syst)±2.7%(stat)±5%(lum)Wt-channel/= 23.9%(syst)±8.8%(stat)±9.9%(MC)s-channel/= 31%(syst)±18%(stat)±5%(lum)
L=10fb-1
L=30fb-1
(CERN/LHCC 2006-021, CMS TDR 8.2)
Separate Channels by (Nj,Nb) in final state:
( <1.5%)
t-channel: Stat: 7000 events (S/B=3)Syst: dominated by Eb-jet and Lum. ErrorBack: tt, Wbb and W+jets(Nj=2,Nb=1)
Wt-channel:
Stat: ~1% (S/B=15%) ( ~ 4%)(Nj=3,Nb=1)
s-channel:
Stat: 1200 events for tb (S/B=10%)Syst: Eb-jet, Lum. Error, back X-section
( ~7-8%)(Nj=2,Nb=2)
3) Conclusions3) Conclusions
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
The LHC will be a top factory (8 million events already with 10fb-
1)
New era on precision Top Quark Physics
will start with the LHC: couplings, asymmetries, decays, etc.
will be measured with unprecedented precision
Stay tuned for next year
Backup SlidesBackup Slides
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 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
Cross-sections at the LHCCross-sections at the LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
ATLAS ExperimentATLAS Experiment
Toroide+Solenoid (4 magnets) in inner cavityCalorimeters outside field
MAGNETSTracker
Si pixels + stripsTRD alows particle IDSolenoid B=2T/pT ~ 5x10-4 pT 0.01
Electromagnetic Calo
Pb-liquid argon/E ~ 10%/E ~1% uniform
Hadronic Calo
Fe-scint Tile Calo (10) /E ~ 50%/E 0.03
Muon Detectors
/pT < 10 % at 1 TeV
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
tt @ LHCtt @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
With only L=100pb-1 (few days of nominal low-lumi LHC operation)
We can easily see top peak without b-tag requirement
Mjjj (GeV)
electron+muon estimate for L=100 pb-1
Even
ts /
4.1
5 G
eV
ATLAS preliminary
3-jet invariant mass
Top-combinatorialand W+jets background
thad=highest pT,3j
W=highest pT,2j
(in thad system)
No b-tag and MW cut
(=5.3%)
tt cross section and top tt cross section and top massmass
ATLAS ExperimentATLAS Experiment
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
ID B
ID A J
N
Cold tests
Limited access (ECT partially inside, half truck)
ID C
Pix
el
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43
Endcap Cal. A services
Cold tests
ID Barrel connection and testing (side C access via lift only!)
Sep '07 Oct '07
EO, side A
Oct '07
JF
Sep '07Oct '06
Jun '07
Big Wheels in park position
JD
Tru
ck
clos
ing
Big Wheel tooling
Endcap Cal. services
Muon Barrel C
LAr C cool down
Aug '07
Jul '07 Aug '07
VT
VT
JF
VJ
Barrel
Muon Barrel C completion
VA
Global Commissioning
EO, side CSmall
Wheel C
Jul '07
Side A
Glo
bal C
omm
issi
onin
g
glob
al te
sts,
pum
p do
wn
& b
ake
out
Side C
VJ
JF
Limited access
JFSide C
Barrel
Side A
ID services along Barrel & through Muons
Chains
May '07 Jun '07
VA
Small Wheel A
Big Wheel A (TGC1 +MDT+TGC2+TGC3)
Mar '07Feb '07Jan '07 Apr '07
ECT on beam line, partially inside (half truck)
Dec '06Nov '06
Nov '06 Jan '07Dec '06
Tru
ck
JT
Mar '07
Endcap Toroid A cooldown
& test
May '07Jul '06 Feb '07Sep '06 Oct '06Aug '06 Apr '07Jun '06
Sep '06Jul '06
Services 1st fixop
en
clos
e
Jun '06 Aug '06
open
ing
Barrel Calo testing and commissioning
ID access via lift only
map
ping
Fiel
dCable chains
BT pumping, cooling, testing
Endcap Toroid C cooldown & test
(Park pos.)
Endcap Toroid C
open
ing
TGC1
Endcap Cal. C testing & commissioning
ID A connection and testingPixel connection and testing
Endcap Toroid A
Muon Barrel AJT
Big Wheels C (TGC1+MDT +TGC2 +TGC3)
IDC connection and testing
LAr A cool down
BT test Magnet test
Time until Friday, August 31, 2007
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
CMS ExperimentCMS Experiment
1 Solenoid (B=4T)Calorimeters inside field
MAGNETTracker
Si pixels + stripsNo particle ID/pT ~ 1.5x10-4 pT 0.005
Electromagnetic Calo
PbWO4 Crystals /E ~ 2-5%/Eno longitudinal segmentation
Hadronic Calo
Brass-scint. (> 5.8 )/E ~ 100%/E 0.05
Muon Detectors
/pT ~ 5% at 1 TeVcombining with tracker
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
Sensitivity to New PhysicsSensitivity to New Physics
Single top @ LHCSingle top @ LHC
Moscow,Moscow, ICHEP 2006 ICHEP 2006 28 July 200628 July 2006
t-channel/ ~10%(tot)s-channel/ ~36%(tot)
L=10fb-1
CERN/LHCC 2006-021CMS TDR 8.2
Tait,Yuan PRD63 (2001) 014018
1-bands (SM )L=10fb-1