António Onofre António Onofre ([email protected]) ([email protected]) Moscow July 26 – Moscow July 26 – Au Au gust 2, 2006 gust 2, 2006 XXXIII International XXXIII International Conference on High Energy Physics Conference on High Energy Physics On behalf of the ATLAS+CMS Collaborations Testing the SM in tt and Testing the SM in tt and single top production single top production
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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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