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TOP QUARK PHYSICS .

TOP QUARK PHYSICS. STATUS @ TEVATRON PROSPECTS @ LHC,ILC. M top Tevatron Average. Weight (%). Δ M TOP = 1.3 %. Published Run-I (1992- 1996) measurements combined with the most recent preliminary Run-II (2001- present) measurements using up to 750pb -1 of data.

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TOP QUARK PHYSICS .

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  1. TOP QUARK PHYSICS. STATUS @ TEVATRON PROSPECTS @ LHC,ILC

  2. Mtop Tevatron Average Weight (%) ΔMTOP= 1.3 % Published Run-I (1992- 1996) measurements combined with the most recent preliminary Run-II (2001- present) measurements using up to 750pb-1 of data.

  3. Current Mtop Avg. Impact on MH Limit (Martin Grünewald, LEPEWWG, TEVEWWG) EWK fit value Fit limit including theory uncertainty: If LEP direct search limit is included: LEP direct search limit

  4. Mtop @ LHC … @ the Tevatron … @ the LHC L~10fb-1 we expect per exp.: stat ~0.1-0.2 GeV syst ~1 GeV Mtop measured <1 GeV should be achievable at CMS/ATLAS. (hep-ex/0403021 hep-ph/0003033, ALTAS TDR, CMS 2001/001) THE DATA MAKES US SMARTER!

  5. Mtop AND THE ILC • Smaller ΔMTOP from Tevatron & LHC (~ 1 GeV ): • smaller the energy interval for threshold scan for tt-bar production @ ILC • ΔMTOP ~ 100 MeV from production threshold scan using NNLO calculations in terms of a “threshold top-quark mass parameter” • (hep-ph/0410364 & • hep-ph/9903260 & • hep-ph/0106315)

  6. Single top production @ Tevatron 2.44 ± 0.12 pb Steltzer, et al. ‘98 0.88 ± 0.12 pb Smith/Willenbrock ‘96 s<0.1 pb Tait ‘99 Not Yet Observed

  7. Search for Single Top S/B~1/20) require very sophisticated analysis techniques. • Use l +MET+2jet (>=1 btag) events: same signature as tt-bar → WH (H →bb-bar) • s and t-channel searched jointly and separately (have different sensitivity to new physics).

  8. Single Top Limits • (695 pb-1) has 2 analysis: • Neural Network • Multivariate Likelihood function • 95% observed (expected) exclusion limit getting close to SM expectations! • Projections (ignoring syst): • 2.4 s excess with 1 fb-1 • 3 s excess around 1.5 fb-1 CDF Preliminary

  9. Direct determination of the tWb vertex (=Vtb) Discriminants: - Jet multiplicity (higher for Wt) More than one b-jet (increase W* signal over W- gluon fusion) 2-jets mass distribution (mjj ~ mW for the Wt signal only) Three production mechanisms: Main Background [xBR(W→ℓ), ℓ=e,μ]: tt σ=833 pb [ 246 pb] Wbbσ=300 pb [ 66.7 pb] Wjjσ=18·103 pb [4·103 pb] Single top production @ LHC W* 10.2±0.7 pb M.Smith et al., Phys.Rev.D54, 6696 Wg fusion: 245±27 pb S.Willenbrock et al., Phys.Rev.D56, 5919 Wt: 62.2 pb A.Belyaev, E.Boos, Phys.Rev.D63, 034012 +16.6 -3. 7 Wg [54.2 pb] Wt [17.8 pb] W* [2.2 pb]

  10. Single top prospects @LHC Stan Bentvelsen ( Moriond QCD-04) • Signal unambiguous, after 30 fb-1: • Complementary methods to extract Vtb for the 3 production mechanisms • With 30 fb-1 of data, Vtb can be determined to %-level or better (experimentally)

  11. Single top production @ ILC hep-ph/0410364 E.Boss et al (hep-ph/0207055) tt-bar is the main background: Rejection with M(evb)-cut σ(e+e- → evtb) ~ | Vtb | 2 Δ(Vtb) ~ 6% ( similar to LHC) (Sqrt(s)=0.5 TeV, M(evb)-cut=5 GeV, L=5X1033) Δ(Vtb) ~ 1% (improved w.r.t LHC prospects) (Sqrt(s)=2 TeV, M(evb)-cut=5 GeV L=5X1034 )

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