Prospect for Top Properties Measurement in Atlas A.Onofre (onofre@lipc.fis.uc.pt) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Outline Top Properties Conclusions Top Mass Top Charge Top Spin and Spin Correlations Top tWb decay Top FCNC decays FCNC in Single-t Production tt Resonances Conclusions Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Most of the Studies done with tt Events Top Mass, Top Charge, Top Spin and Spin Correlations, Top tWb decay and tt Resonances Semileptonic Topology Dileptonic Topology 2 b-jets pT>20GeV ≥4 jets,DR=0.4 pT>40GeV t(had) t(lep) W(had) e,m b W 2 b-jets 2 leptons Top FCNC decays and FCNC in Single-t Production use different analyses Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Charge SM Exotic For top quark determination Critical moment SM (Qtop=+2/3): Exotics (Qtop= -4/3): Exotic t(-4/3) b(-1/3) W- l-(-1) nl SM t(2/3) b(-1/3) W+ l+(+1) nl Critical moment For top quark determination I) Determination of b-jet charge II) Correct (lepton, b-jet) pairing (Atlfast, PHYS-2003-35) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Charge I) Determination of b-jet Charge: A) Weighting Technique: B) Semileptonic Decay: II) Correct (l±, b) Pairing: 1) Semileptonic Channel 2) Dileptonic Channel Invariant mass criteria: l and b2 from different tops l and b1 from the same top Mtop=175 GeV ( Cut optimized for mcr=145 GeV ) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Charge A) Weighting Technique: B) Semileptonic Decay: b (B.Zilka,S.Tokar) A) Weighting Technique: b -0.0842  0.0044 0.0868  0.0043 ( Eff.=4.1% Purity: 89.3% ) L=1fb-1 l+ l- B) Semileptonic Decay: (A. Tonoyan) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Spin and Spin Correlations tt Spin Correlation Parameters: Although t and t not polarised in tt pairs, their spins are correlated (Zhu Chengguang) Mtt<550 GeV A=0.42 Double Angular Distributions: Mtt<550 GeV AD =-0.29 Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Spin and Spin Correlations (Eur.Phys.J.C44S2 2005 13-33) L=10fb-1 ATLFAST (reminder) -0.29 0.42 SM 0.008 0.010 AD 0.014 0.023 A Error (±stat ±syst) Semileptonic + Dileptonic Syst (Eb-jet,mtop,FSR) 4-6% precision FULLSIM (CSC) L=1fb-1 Preliminary Semileptonic Selection efficiency 2.9% (2.7% for rome) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Spin and Spin Correlations Trigger Studies: Isolated single electron trigger Single muon trigger Results (Preliminary): Level of Precision of A, AD ~40% L=1fb-1 Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Spin and Spin Correlations Spin Asymmetries can also be used: (spin analysing power al+=1.0, aj=-0.51) Error versus Luminosity: Alj SM (LO): Alj=-0.0396 L=1fb-1 Level of Precision of Alj~40% (Low MC) Alj~30% (High MC) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 1) the tWb decay By measuring the fraction of longitudinal W´s in top quark decays we are: Testing a Standard Model prediction: F0=0.7 FL=0.3 Probing the structure of the Wtb vertex V-A SUPPRESSED Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 1) the tWb decay How to measure the W Helicity Fractions? Using lepton angular distribution (with respect to top direction) in W cm system: SM(LO): F0=0.703 , FL=0.297 , FR=3.6x10-4 (NLO): F0=0.695 , FL=0.304 , FR=0.001 Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 1) the tWb decay (Eur.Phys.J.C44S2 2005 13-33) L=10fb-1 ATLFAST (reminder) Syst ( Eb-jet,mtop,FSR ) dF0/ F0 ~ 2% ; dFR ~ 0.01 FULLSIM (CSC) L=1fb-1 Results (Preliminary) dF0/ F0 ~ 6% ; dFR ~ 0.03 (Zhu Chengguang) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 1) the tWb decay Anomalous Couplings @ the Wtb Vertex VR,gL,gR Change F0,FL,FR Eur.Phys.J. C50 (2007) 519-533 How to Probe Anomalous Couplings? Extract Limits from F0,FL and FR (and ratios) Fit angular distr. with VR, gL and gR (mb≠0) Use Angular Asymmetries Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 1) the tWb decay Angular Asymmetries: (SM, LO): AFB=-0.2225 , A+=0.5482 , A-=-0.8397 (NLO): AFB=-0.2269 , A+=0.5429 , A-=-0.8402 Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Likelihood Distributions: Top Decays: 1) the tWb decay (SN-ATLAS-2007-064) ATLFAST (reminder) L=10fb-1 (SM, LO) FULLSIM (CSC) L=1fb-1 Likelihood Distributions: e+m e m Three Different Samples: e, m, e+m Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Error Versus Luminosity Top Decays: 1) the tWb decay (N. Castro) Asymmetries Error Versus Luminosity L~1fb-1 A+ A- Anomalous Couplings Flavour at the LHC Era Yellow Report (in prep.) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Br(tqX) in Several Models: FCNC Decays in tt Events Top Decays: 2) Rare decays (FCNC) Top FCNC Decays: tqg tqZ tqg Br(tqX) in Several Models: Studied Decays: FCNC Decays in tt Events Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 2) Rare decays (FCNC) In the absence of signal: ATLFAST (reminder) L=10fb-1 Current Limits: Expected 95% CL Limits: Br(tqg) <1.3x10-3 5s Results: Br(tqZ) >4.4x10-4 Br(tqg) >9.4x10-5 Br(tqg) >4.3x10-3 (SN-ATLAS-2007-059) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Top Decays: 2) Rare decays (FCNC) FULLSIM L=1fb-1 Results Crucially Depend on Tagging Efficiencies (e, m, b, jets and g) Likelihood Method works (need to have well defined shapes) Gluon Channel more difficult 5s Results: Br(tqZ) ~ 10-2 - 10-3 Br(tqg) ~ 10-3 Br(tqg) ~ 10-2 (F. Veloso) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Back: W+j(80%), single-t(9%) FCNC in Single-t Production (T.L. Cheng) “Direct” L=10fb-1 ATLFAST (reminder) kqg=anomalous coupling L =scale of new physics Results: Event Selection: 1 lep ( pT>20GeV, |h|<2.5 ) 1 b-jet ( pT>40GeV, |h|<2.5 ) pT > 20GeV ( W and t pT, mbl, mT(W), HT, mt ) Systematics: Dssignal (8%), btag (6%), ISR (3.5%), PileUp (4%) Total ~ 12% e(ug)=1.08%, e(cg)=1.81% Back: W+j(80%), single-t(9%) (hep-ex/0702005) Br(tug)~O(10-3) Br(tcg)~O(10-2) Estimate: Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

FCNC in Single-t Production The Direct Production is not the full Story The ggqt Processes: Phys.Rev. D74 (2006) 014006 The X-section: The gqgt Processes: The X-section: Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Back:W+j(50%),t-chan(25%) tt(21%) FCNC in Single-t Production Just To Have an Idea of the Results: New Contributions Included in MC (TopReX 4.20) Event Selection: 1 lep ( pT>30GeV, |h|<2.5 ) 1 b-jet ( pT>50GeV, |h|<2.5 ) 1 non b-jet ( pT>25GeV, |h|<2.5 ) pT > 25GeV Likelihood Analysis e(qg)=1.4% Back:W+j(50%),t-chan(25%) tt(21%) L=10fb-1 Very Preliminary PT(W) mlb Cos(qn*) Cos(ql) Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

FCNC in Single-t Production Just To Have an Idea of the Results for : L=10fb-1 5s and 95% CL Limits obtained 5s Discovery 95% CL Limit: 95% CL Limits: Br(tqg) ~O(10-4) 5s Discovery: Br(tqg) ~ O(10-3-10-4) New Contributions Give Same Order of Magnitude Results as Direct Production Mechanism 1 Order of magnitude better than ttbar for the gluon channel Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC

Conclusions Already @ 1fb-1: Atlas will allow to perform precision studies Object Reconstruction (e, m, t, jets and g) Requires Care Several Methods Available to Extract Physical Observables Already @ 1fb-1: Top Charge (2/3 versus -4/3) > 5s significance Spin Correlation Parameters (A,AD) ~ 40% error Spin Asymmetries ~ 40% error W helicity fractions (F0, FL, FR ) ~ 6%, ~10% and ~0.03 error Angular Asymmetries (A+,A-) ~ 3% and 1% error Anomalous Wtb Couplings (VR, gL, gR ) ~ 0.1, 0.05 and 0.03 error FCNC top Decays (Br[tqX], X=g,Z,g) ~ 10-2 - 10-3 Grenoble, 20 October 2007 Workshop on Top Physics : from the TeVatron to the LHC