Prospects of measuring the CKM matrix element |Vts| at the LHC
In: Physics letters. Section B, Jg. 693 (2010), Heft 1, S. 44-51
academicJournal
- print, 38 ref
Zugriff:
We study the prospects of measuring the CKM matrix element |Vts| at the LHC with the top quarks produced in the processes pp → tt̄X and pp → t/t̄X, and the subsequent decays t → W+s and t̄ → W-s̄. To reduce the jet activity in top quark decays, we insist on tagging the W± leptonically, W± → ℓ±νℓ (ℓ = e, μ, τ), and analyse the anticipated jet profiles in the signal process t → Ws and the dominant background from the decay t → Wb. To that end, we analyse the V0 (K0 and A) distributions in the s- and b-quark jets concentrating on the energy and transverse momentum distributions of these particles. The V0s emanating from the t → Wb branch have displaced decay vertexes from the interaction point due to the weak decays b → c → s and the b-quark jets are rich in charged leptons. Hence, the absence of secondary vertexes and of the energetic charged leptons in the jet provide additional (b-jet vs. s-jet) discrimination in top quark decays. These distributions are used to train a boosted decision tree (BDT), a technique used successfully in measuring the CKM matrix element |Vtb| in single top production at the Tevatron. Using the BDT classifier, and a variant of it called BDTD, which makes use of decorrelated variables, we calculate the BDT(D)-response functions corresponding to the signal (t → Ws) and background (t → Wb). Detailed simulations undertaken by us with the Monte Carlo generator PYTHIA are used to estimate the background rejection versus signal efficiency for three representative LHC energies √s = 7 TeV, 10 TeV and 14 TeV, of which only the analysis for the √s = 14 TeV case is shown in detail. We argue that a benchmark with 10% accuracy for the signal (t → Ws) at a background (t → Wb) rejection by a factor 103 (required due to the anticipated value of the ratio |Vts|2/|Vtb|2 ~ 1.6 x 10-3) can be achieved at the LHC@14 TeV with an integrated luminosity of 10 fb-1.
Titel: |
Prospects of measuring the CKM matrix element |Vts| at the LHC
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Autor/in / Beteiligte Person: | ALI, Ahmed ; BARREIRO, Fernando ; LAGOURI, Theodota |
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Zeitschrift: | Physics letters. Section B, Jg. 693 (2010), Heft 1, S. 44-51 |
Veröffentlichung: | Kidlington: Elsevier, 2010 |
Medientyp: | academicJournal |
Umfang: | print, 38 ref |
ISSN: | 0370-2693 (print) |
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