Single Top Search ~ New Kinematics Fitter ~ K Nakamura

S-channel single top CM Frame W* t b b l ambiguity Selection of bjet from top quark t-channel : tagged jet -> 95% s-channel : tagged jet -> 53% CDFNOTE top mass resolution +15 GeV Selection of neutrino Pz solution 30% … no solution M l b : for 4 cases This Top Mass constraint gave some bias to Mlnb distribution??

Neutrino solution

Likelihood Function for neutrino Pz To define a Likelihood as the function of Neutrino Pz Move three parameters: METx METy P Z 2 solution case 0 or 1 solution case

P ---- W* W* - To have pronounced tendency to separate W*+ and W*- PP W*- t b b l- W*+ t b b l+ +Z correct wrong

P Z *Q ---- correct ---- wrong

W* t b b l M W* 2 > M t 2 +M b 2 ~ M t 2 M W* =q 2 =s ^ W* has the mass as small as possible to keep larger than Mt…?? W* mass

M Using L5 jet No b jet correction

Likelihood … correlation check M W* P Z *Q lep

MET Gaussian Double Gaussian We use this one !

Result of the Likelihood fitting

bbbar ambiguity

Likelihood Function for bbbar ambiguity  is the angle of Wstar Rest Frame

B-jet Pt distribution W* t b b l Using L5 jet No b jet correction Gen LevSim Lev -- top -- other -- top -- other Use these distribution as the Probability Density Function

M lb distribution W* t b b l Using L5 jet No b jet correction Gen LevSim Lev -- top -- other -- top -- other Use these distribution as the Probability Density Function

cos  b x Q lep PP W*- t b b l- W*+ t b b l+ +Z tb production process has the V-A coupling, so it is easy for the b-jet to be produced in the direction of quark in proton, and bbar-jet to be produced in the direction of anti-quark in the Wstar rest frame.  Wstar Rest Frame cos  angle shown in upper figure times lepton charge is the powerful variable to select b-jet which is directory produced form Wstar.

cos  b distribution Gen Lev Sim Lev topother topother ---- W* W* -

cos  b x Q lep distribution Gen Lev -- top -- other Sim Lev -- top -- other Use these distribution as the Probability Density Function

Parameter correlation These figure shows some correlations between the Likelihood parameters…… But Likelihood is only used as the choosing bbbar ambiguity, so we use this likelihood !

Top Specific Correction for b-jet

Correlation Factor as the function of Pt Eta

After Correction check

Top Mass Distribution Linear ScaleLog Scale

Wbb background Shape ---- Wbb ---- Signal Normalization is not correct… Use MC Wbb+0j bkg

---- Wbb ---- Signal Mlnb distribution normalized by # of events of CDFnote Wbb events s-channel events At least 1 b-tag

64.3% 29.5% 52.4% 19.7% B-tag 45.9% 37.6% SignalW(mu)bb

---- Wbb ---- Signal At least 1 b-tagS+S S+J double tag Double tag… ---- Wbb ---- Signal Enhancement !?

Conclusion  We developed new likelihood fitter without using top mass constraint Make Likelihood fitter like blow : For the 75.2% events of the 2 solution events we can choose the correct solution.  After decided neutrino Pz, we can choose the correct b-jet from the top quark for the 81% of the total events.  But Mlnub distribution is not so improved…  We will try to check correlation between the likelihood variables and top mass 2 solution case 0 or 1 solution case

Backup

W* t b b l wrong correct P ---- W* W* - Bug is Fixed !

P Z *Q ---- correct ---- wrong

W* t b b l wrong correct M

Probability Density Function

Neutrino Solution Check Choose Correct Solution Result of the Likelihood fitting What?? P Z =0 ??

-2Log L distribution as the function of P Z First 6 events…

Likelihood distribution for the case of P Z =0 Most likely P Z is really 0 ?? Is this correct??

---- correct ---- wrong corr wrong 72.7% 75.2% Likelihood for Solution corr wrong