2 The CDF Experiment at Fermilab Contents - Harvard University ...

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84 Section 2: CDF Physics Analysis LVL1 ΣE t >70GeV,LVL2 nj≥2 j1>20 j2>20,NXFT Tracks > 12, >2 SVT Tracks d 0 > Scan, LVL3 ≥2 SECVTX 10 2 10 0.005 0.0075 0.01 0.0125 0.015 0.0175 0.02 0.0225 0.025 0.0275 0.03 10 2 10 1 10 -1 10 -2 0.005 0.0075 0.01 0.0125 0.015 0.0175 0.02 0.0225 0.025 0.0275 0.03 Figure 41: The signal eciency (top) and the rate (bottom) as a function of the impact parameter (d 0 ).
Section 2: Run II Triggers 85 for b-tags. The B group plans to make use of leptons with p T as low as 2 GeV/c. The leptonic information is used at Level 1, which only reduces the rate compared to our `default' (SVT-based) tagging option. At the Level 2, due to B meson semileptonic branching fractions, the lepton trigger is comparable to a trigger based on displaced tracks from SVT. The missing bit of information is the eect of the muon fakes and electron conversions (the inner detector has more matter in Run II, and the conversion rate is expected to increase compared to Run I data). Student David Medvigy is also involved in this study. We envision a combined SVT-based and lepton-based trigger, that uses the lepton info at Level 1 if it is available, and then meshes the leptonic and displaced-track tags at Level 2. We plan to set the cuts on displacement(jd 0 j) and lepton p T so that they are almost interchangeable, and in that way dene one dataset comprising of SVT-SVT, SVT-lepton and lepton-lepton b-tags. 3. b-tagging algorithms at Level 3: our current work is based on two SECVTX tags at Level 3. However, we consider SECVTX to be `destructive', in a sense that it has high purity at the expense of signal eciency. We would prefer to use an algorithm more ecient for the H + W=Z signal at Level 3, allowing for more maneuvering room oine. 4. b-jet mass resolution: the di-jet mass resolution is crucial for the sensitivity to higgs signals. As discussed in the next section, advances there will improve the performance of this trigger, too. 5. Oine analysis: There are two levels of involvement: (a) Use existing Run I code and SECVTX tagging to update the Run I limit in the light of the change in the trigger. (b) Update the limit using the Run II software tools. This would also prepare us for the Run II data, and may feed back into the Level 3 b-tagging algorithms, which will also be based on the Run II software tools. In conclusion, although there are several technical issues that still remain to be settled, we have veried that the fundamental ideas behind this trigger are sound, and that such a trigger is viable in Run II.
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1 2 The CDF Experiment at Fermilab
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Section 2: CDF 3 of Run I data. Rec
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Section 2: CDF Hardware Projects 5
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Section 2: Central Outer Tracker 7
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Section 2: DAQ for the Silicon Vert
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Section 2: Central Muon Extension 2
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Page 36 and 37: 36 Section 2: CDF 2.3 Run I Physics
Page 38 and 39: 38 Section 2: CDF Physics Analysis
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Page 99 and 100: Section 2: CDF 99 The Jet Pseudora
Page 101 and 102: Section 2: CDF 101 while the proble
Page 103 and 104: Section 2: CDF 103 Talks at Confere
Page 105 and 106: Section 2: CDF 105 References [1] T
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