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Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation.

Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation. Introduction. Trigger will use tracking at the earliest phase of the trigger Maybe use CAL as a throttle, but at 2e33, with reduced CAL thresholds, 80% of events trigger… Idea: “Level1”

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Triggering in Upgrade S. Blusk 10-28-09 Note: I fixed some bugs I this after the presentation.

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  1. Triggering in UpgradeS. Blusk10-28-09Note: I fixed some bugs Ithis after the presentation.

  2. Introduction • Trigger will use tracking at the earliest phase of the trigger • Maybe use CAL as a throttle, but at 2e33, with reduced CAL thresholds, 80% of events trigger… • Idea: • “Level1” • Generic search for high pT tracks that are displaced from closest PV (large IP) • Form 2-track vertices and make a series of cuts on these two track vertices • Build secondary vertex “seeds”. • This could be the list of good 2-track vertices, along with a list of “compatible tracks” or, could build N-track vertices • “Level2” • Hypothesis building of specific decays, as in the current HLT2 exclusive • Also keep various “inclusive” decay signatures

  3. Basic Flow of Trigger • Get all PVs in the event • Identify tracks with large IP to closest PV (~50-100 um) • Other various quality cuts could be applied here, such as qmin, track c2/DOF… • Upgrade selected tracks to VeloPixTT tracks • ~10-15% pT measurement now available • Remove low p, pT tracks • Cut on pT, IPS (pT> 1.0 GeV, IPS>3.0) • Form 2 track vertices from list of selected tracks. Cut on: • DOCA < 0.08 • ZSV – ZPV >1.8 mm • PT Cuts on leading & companion: pTL > pThigh (1.25 GeV) & pTC > pTlow (1.0 GeV) • Slope Cut (nominally done at Step 2 if used) (23 mrad) • Pointing Cut < 0.4 • Track Chisquare/DOF Cut (< 4.5) • Look at # events selected • With 4 long tracks • With 4 VeloPixTT tracks (require at least 3 hits in TT stations, to call it “reconstructed) • With 4 VeloPixTT + Long tracks Try to basically reproduce Victors set of cuts using GaudiPython

  4. Look at Bsff Events, Aerogel Out MC - 2e32 • 1000 events (assume DecayProdCut?) e~ 20% • All events with PV • ≥2 Kaons from Bs in Acceptance • ≥ 2 kaons with IP>100 um • ≥ 2 kaons with pT>1 GeV • ≥ 2 kaons with IPS > 3 • At least 1 SV with DOCA < 80 um • DZ>1.8 mm, DR<6.0 mm • pT cut on leading & companion (1.25, 1.0 GeV) • Slope > 23 mrad on lead. & comp. • “Pointing” < 0.4 • Chi2/DOF < 4.5 • .. • 4 Kaons recon as long • 4 Kaons reconstructible as VeloPixTT • (13) + (14) combined Each number in the histogram isthe # surviving events AFTER thegiven requirement above. Histogram bar from 10-11 is the number of surviving events after the chi2/DOF cut

  5. Summary of Results Note: In LHCb efficiency studies, we measure trigger efficiency with respect tooffline selected events. At this stage of the study, I am only dealing with“tracks”, not “particles”*. Current trigger gives etot = 0.5% (no HLT2) So, we get ~2X improvement. To be more clear though, I will run over “offline selected” events.

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