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First Heavy Flavor Results Using the Silicon Vertex Trigger

This paper discusses the use of the Silicon Vertex Trigger (SVT) in heavy flavor physics at the Tevatron, focusing on tracking at the trigger level. It explores the challenges of tracking at trigger level, presents results from the TwoTrackTrigger (TTT), and showcases the observation of fully hadronic B meson decays.

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First Heavy Flavor Results Using the Silicon Vertex Trigger

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  1. First Heavy Flavor Results Using the Silicon Vertex Trigger A. Cerri

  2. Detector Raw Data 7.6 MHz Crossing rate 132 ns clock hits XFT hits SVT Level 1 storage pipeline: 42 clock cycles Level 1 Trigger • Level 1 • 7.6 MHz Synchronous Pipeline • 5544 ns Latency • 50 KHz accept rate COT d0, 0, Pt L1 Accept Level 2 Trigger d0 L2 Accept • Level 2 • Asynchronous 2 Stage Pipeline • 20 s Latency • 300 Hz accept rate L3 Farm The SiliconVertexTrigger 20s !!! A. Cerri, LBNL

  3. The TwoTrackTriggeris just a selection based on the SiliconVertexTrigger... • Why so much emphasis on tracking at trigger level? • B physics at hadron colliders has two main features: • Large cross section O(0.1 mb !!!) • Huge background O(0.05 b !!!) • So far CDF has only one cure: require leptons • There comes the challenge: tracking at trigger level with sufficient resolution! The TTT is the first case in which CDF investigates low Pt B physics without explicitly requiring leptons A. Cerri, LBNL

  4. First HF signals... • Offline confirmation of TTT cuts • z(K-) < 5cm • Lxy(D) > 500 um • d0(K)*d0()  0 • PT(D) > 5.5 GeV/c • Offline confirmation of TTT cuts • z(K- 1,K- 2, 1-2) < 5cm • Lxy(D+) > 800 um • 2xy<30 • PT(D+) > 6 GeV/c A. Cerri, LBNL

  5. …something even cleaner • Offline confirmation of TTT cuts • z(K- , K-s, -s) < 4cm • m(D0)[1.56,2.16] MeV • Q(K)*Q()<0 Q(K)*Q(s)<0 • R(D0-s)<0.2 |m(D0)-m(D0 PDG)|[0.25,0.3] GeV |m(D0)-m(D0 PDG)|<0.1 |m(D*)-m(D0)-0.1455|<3 MeV A. Cerri, LBNL

  6. Prompt D0 d0(D) Primary Vertex d0(D) Secondary Vertex Primary Vertex D0 Secondary Vertex Tertiary Vertex D0 Secondary D0 Is the Tevatron/CDF a charm factory?!?? • Get a clean charm sample • d0(D) distributed differently for prompt/non prompt • Careful modeling exploiting K0 and analytic models FB=[16.40.7(stat)]% There's Plenty of Prompt Charm!

  7. CP eigenstates... With a selection very close to the K signal we see D0 decays to CP eigenstates, with incredible yields! are already accessible with good statistical accuracy and reasonable systematics!!! (D0)/(D0K) (D0KK)/(D0K)

  8. KK//K relative BR • Is a good benchmark • PDG measurements have errors close compared to our current statistics • Systematics is reasonable because K//KK share: • Selection • Kinematics • Mass

  9. And something strange ! • Offline confirmation of TTT cuts • z(K-K) < 4cm • m()[1010,1035] MeV • z(-) < 4cm • 2(r)<7 • Lxy(D) > 500 um • helicity cut cos(helicity)>0.4 • keep candidate with largest helicity • Fit gaussians+linear background • 135060 events • 7.10.4 MeV/c2 • S/B0.76 Yum… • 236070 events • 8.40.2 MeV/c2 • S/B1.4 A. Cerri, LBNL

  10. Systematics m(D+-Ds) • Is a good benchmark • PDG measurements have errors close compared to our statistics • Systematics is reasonable because D+/Ds share: • Selection • Kinematics • Mass Previous PDG average: 99.20.5 MeV/c2

  11. What about Bees? (I) • Offline confirmation of TTT cuts • M(D0) within 4 • z(tracks) < 5 cm • 0<Lxy(D)<4 mm • (D-) < 2 rad • d()*d(D) < 0 • |d(B)|<100m • Pt(B)>5.5 GeV A. Cerri, LBNL

  12. What about Bees? (II) • Offline confirmation of TTT cuts • Lxy > 0.05 • |eta(B)| < 1 • |d()| > 0.02 • |d(B)| < 0.075 • Isolation: > 0.5 A. Cerri, LBNL

  13. Comments on Yields • Signals based on 10pb-1 out of 2fb-1 to come... • The data sample comes from commissioning with: • partial Si coverage • Non optimized trigger • Reliably understand these differences in simulation • Expect x3 improvement in TTT B physics yields • Additional improvements in offline efficiency expected A. Cerri, LBNL

  14. Conclusions... • Plenty of Charm! • Good benchmark for two body charmless B decays: • Energy scale, PID and dE/dx • By themselves: • Large statistics “world class” charm physics: • m(Ds-D+) • {(D0), (D0KK)} / (D0K) • These are good physics benchmarks of what we will be able to do with the full statistics! • Charmed/uncharmed B are showing up! • First observation of fully hadronic B (hh, D0) • Background rates compatible with predictions • Yields fully understood • Now the fun begins!!! A. Cerri, LBNL

  15. Backup Slides A. Cerri, LBNL

  16. CDF II • Renewed detector & Accelerator chain: • Higher Luminosity higher event rate • Detector changes/improvements: • DAQ redesign • Improved performance: • Detector Coverage • Tracking Quality A. Cerri, LBNL

  17. L1: • Two XFT tracks • Pt1>2 GeV Pt1+Pt2>5.5 GeV • <135° • L2: • d0>100 m for both tracks • Validation of L1 cuts and >20° • Pt•Xv>0 • d0(B)<140 m • L1: • Two XFT tracks • Pt1>2 GeV Pt1+Pt2>5.5 GeV • <135° • L2: • d0>120 m for both tracks • Validation of L1 cuts and >2° • Pt•Xv>0 • d0(B)<140 m Low Mass High Mass Two Body Many Body Two Paths... PiPi DsPi A. Cerri, LBNL

  18. How does it look like? A. Cerri, LBNL

  19. Prompt fractions... [16.40.7(stat)]% [11.41.4(stat)]% [11.30.5(stat)]% [34.82.8(stat)]%

  20. Backup slide IHow well do we know how to model the trigger selection/detector effects? A. Cerri, LBNL

  21. + K-  K+ D Backup Slide IID+-Ds cuts

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