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Missing B-tracks in L1 trigger

Missing B-tracks in L1 trigger. Federica Legger. Summary. Motivations Method used L1 flow and main failures Breakdown for some representative channels Results A case study: B d  p + p - L1 failures correlation Origin of the decision tracks Status and plans. Motivations.

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Missing B-tracks in L1 trigger

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  1. Missing B-tracks in L1 trigger Federica Legger

  2. Summary • Motivations • Method used • L1 flow and main failures • Breakdown for some representative channels • Results • A case study: Bdp+ p- • L1 failures correlation • Origin of the decision tracks • Status and plans

  3. Motivations LHCb trigger TDR (September 2003) • TDR L1 efficiencies… • or inefficiencies: why do we lose 37.3% of the events for Bdp+ p- (easy channel)?? • Some bugs corrected after TDR Post-TDR study to better understand L1 behaviour

  4. What I did…(I) • Take some representative channels, and select events which pass L0 and the offline selection ( reconstructible), but that are rejected by L1 Hadronic Muon Electro magnetic

  5. …what I did… (II) • Look for signal decay tree (MC Truth); • Consider B daughter which is more likely to trigger: • In the cases where there are more than one particle with the same probability to trigger (Bd p+p-), I consider the one with the highest Pt; • Bdp+ p- • Bs Dsk • BdF Ks • Bs J/ (m+ m-) F • Bs J/ (e+ e-) F • BdK*g

  6. …what I did (III) • Associate MC particle to L1 2D and 3D tracks; • Look what happened to signal track and see why it didn’t trigger; • Classify events according to trigger failures; • Study of L1 failures correlations in Bdp+ p-(both pions taken in account).

  7. (r,z) plane r z Match L0 m to 2D tracks (2<16) L1 flow (I) VELO hits NO 2D Reco YES 2D PV, IP2D IP2D cut .15 <IP2D< 3 mm NO NO Muon YES YES 3D Reco NO YES Track rejected 3D PV, IP3D

  8. m match to retrieve tracks for dimuon mass bonus (out of scope) Match to TT or m (Pt) If not assign default 400 MeV/c One of the two highest Pt track (PT1 and PT2) D L1 flow (II) Backward, Weird IP (-2<IP3D<5mm), IP3D cut (.15<IP3D<2mm) NO YES PT, IPS Decision track NO YES Track rejected L1 Plane cut D > L1 equivalent 4% min. bias ret. YES NO L1 YES L1 NO

  9. L1 code • TDR baseline version + some bugs fixed (PVZ @ 100mm) • No bonus system (dimuon mass, electron and g transverse energies) • No multiple PV treatment (implemented in new L1 code) TDR now PVZ PVZ

  10. L1 flow (I) Main failures VELO hits NO 2D Reco YES 2D PV, IP2D Lost@2D 1 IP2D cut .15 <IP2D< 3 mm NO NO Muon YES YES 3D Reco NO YES Lost@3D 2 Track rejected 3D PV, IP3D

  11. L1 flow (II) Lost@3D Backward, Weird IP (-2<IP3D<5mm), IP3D cut (.15<IP3D<2mm) NO YES Main failures PT, IPS Low PT Decision track 3 NO YES Track rejected L1 Plane cut D > L1 equivalent 4% min. bias ret. Small D 4 YES NO L1 YES L1 NO

  12. Bdp+ p- Bs Ds K BdF Ks Bs J/ (e+e-) F Bd K* g Main failures To be treated separately Main loss (~60%) ~10% ~10% ~15%

  13. IP2D cut Or Muon 2D track MC truth B daughter Lost@2D Correct Wrong 2. Tracks lost at 2D

  14. Bdp+ p- Bs Ds K BdF Ks Bs J/ (e+e-) F Bd K* g Absolute Relative Tracks lost at 2D Main loss ~20% OK

  15. IP3D cut IP2D cut Or Muon 2D track 3D track MC truth B daughter Lost@2D Correct Wrong Lost@3D 3. Tracks lost at 3D Correct Wrong

  16. Bdp+ p- Bs Ds K BdF Ks Bs J/ (e+e-) F Bd K* g Absolute Relative Tracks lost at 3D ~2% Main loss

  17. 2D track 3D track IP2D cut Or Muon IP3D cut MC truth B daughter Lost@2D Low PT Default Pt 400 MeV/c Measured low Pt Correct Wrong Correct Wrong Lost@3D 4. Tracks lost because of low Pt Correct Wrong

  18. Bdp+ p- Bs Ds K BdF Ks Bs J/ (e+e-) F Bd K* g Absolute Relative Tracks lost because of low PT insignificant Main loss (~10%)

  19. 3D track 2D track IP3D cut IP2D cut Or Muon MC truth 5. Tracks lost because of small D B daughter Lost@2D Low PT Default Pt 400 MeV/c Measured low Pt Correct Wrong Correct Wrong Lost@3D Small D PT1 PT2 Correct Wrong Correct Wrong Correct Wrong

  20. Tracks lost because of small D Correct > Wrong Correct < Wrong Almost 100% no measured Pt

  21. Bdp+ p- Bs Ds K BdF Ks Bs J/ (e+e-) F Bd K* g Tracks lost because of small D B track is more likely to be PT1

  22. IP2D cut Or Muon 2D track IP3D cut 3D track MC truth Summary for all channels but muons 60% 13% B daughter Lost@2D Low PT 12% 3% Default Pt 400 MeV/c Measured low Pt 37% 20% 0% 1% 12% Correct Wrong 15% Correct Wrong Lost@3D Small D 10% PT1 PT2 1% 1% 10% 2% 2% 1% Correct Wrong Correct Wrong Correct Wrong

  23. Bdp+ p- Bs Ds K BdF Ks Bs J/ (m+m-) F Bs J/ (e+e-) F Bd K* g L1 Design vs. Resolution failures (wrong+failed) (correct boxes) Best channel 50%, 50% Enhanced by bonus...

  24. Results (I) • Main failure: • IP2D cut~60%, wrong (40%) + correct (~20%) • Main loss at 3D: • failed 3D reco (~8%), worse than failed 2D reco (~3%), could also be the associator (MCParticle2L1Track) IP cut IP cut IP2D p+ IP2D e+

  25. IP cut IP cut IP3D p+ IP3D e+ Results (II) • IP3D cutnot very significative(~2%) • No decision track because Pt is too low (~10%): • no measured Pt (~100%)failed TT reco • Rejected decision tracks (~15%) : • if PTMC we would gain ~5% of the evts.

  26. The muon channel • L0 Muons (63%) go to 3D reco even if they do not pass the IP2D cut (73%) • 10% evts lost at 2D (3% wrong) • Main loss at 3D: IP3D cut (61%) • 99% were L0 muons • 13% evts wrongly rejected • These tracks could be later use for dimuon mass bonus (out of scope) • Low Pt tracks: 3% • No decision track: 18% • Worst design (71% vs. 29%) BONUS system

  27. A case study: Bd p+p- Consider the two pions to study failures correlation ! L1 failures • NO2D No 2D track • NO3D No 3D track • IP2D doesn’t pass IP2D cut and is not a m • PT1 Leading track • PT2 2nd leading track • LOWPT Not one of the two leading tracks • IP3D doesn’t pass IP3D cut

  28. A case study: Bd p+p- Main loss is IP2D cut Even if other track is PT1!!

  29. Origin of the decision tracks Bd p+p- L0 && !L1 && SEL L0 && L1 && SEL

  30. PT1 PT2 L0 && !L1 && SEL L0 && L1 && SEL

  31. Status and plans • Study completed; • Note with full results almost ready; • Write a Tool to automatically flag trigger failures and include it into new L1 code.

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