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Search for extra-boson from Top Decays. Jenna Lane, Paul Miyagawa and Un-Ki Yang. Manchester Christmas Meeting, Dec. 20-21. Motivation. Search for extra boson from top decays (top->Xb, where X->jj) using a dijet mass Charged Higgs is a good candidate at low tan( )
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Search for extra-bosonfrom Top Decays Jenna Lane, Paul Miyagawa and Un-Ki Yang Manchester Christmas Meeting, Dec. 20-21
Motivation • Search for extra boson from top decays (top->Xb, where X->jj) using a dijet mass • Charged Higgs is a good candidate at low tan() • Provide a Jet Energy Scale information using a standard W mass W+ b-jet t t jet W- (H-) Mjj jet b-jet
Method • Use a kinematic top mass fitter developed at CDF • Default fitter: M_W(jj)=M_W(ln)=80.4, M(top)=M(anti-top) • Modified fitter: W(ln)=80.4, M(top)=M(anti-top)=175 GeV • Lepton+jet channel with double b-tagged events W (80) H+(120) top->H+b, H+->csbar using CDF MC
Improvements in dijet mass? • Poor resolution for Njet>4 • Better handling on the 5th jet • Detailed studies of extra jets • ΔR (5th-jet, L4jet)<1, merge it • Good improvement For 2 Hjets
Status and Plan • A dijet mass resolution has been improved. • A binned likelihood fitter works. • Plan to make ATLAS MC samples and finish sensitivity studies • Jenna Lane (student) and Paul Miyagawa (postdoc) will join this effort. toy exp.:H:W:B=1:1:1
Other Activities • Systematic studies on the extra-jets (ISR/FSR) • Dominant systematic for precision measurements at LHC • Extend CDF ISR/FSR studies to LHC region with other ATLAS colleagues • High Level Trigger: plan to spend 50% efforts on this projec. qqbar->bbbar @LHC By M. Cobal
Backup • Current Limit on the charged Higgs BR(tH±b)<0.4 @95%CL Assuming BR(H±tn) = 1