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Probing Hot and Dense Matter with Charm and Bottom Measurements with PHENIX VTX Tracker

This paper presents the measurements of charm and bottom quarks using the PHENIX VTX Tracker, providing insights into the properties of hot and dense matter. The study includes the suppression and collective behavior of heavy quarks, as well as the mass hierarchy of energy loss. The paper also compares the theoretical predictions with the experimental results.

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Probing Hot and Dense Matter with Charm and Bottom Measurements with PHENIX VTX Tracker

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  1. Probing Hot and Dense Matter with Charm and Bottom Measurements with PHENIX VTX Tracker Rachid Nouicer, BNL for the PHENIX Collaboration Quark Matter 2012 International Conference, August 13-18, 2012, Washington, DC 20008 USA

  2. PHENIX Open Heavy Flavor: eHF One of the most surprising results from RHIC • Electrons fromHeavy quarks suppressed, and they flow. • Collective behavior is apparent in eHF; but HF v2is lower than v2 of  p0 for pT > 2 GeV/c. PRC 84 (2011) 044905 Au+Au • Separating charm and bottom is the key to understand the mass hierarchy of energy loss.

  3. What the Theory Telling us Probe deeper into the medium: Energy loss of heavy quarks nucl-th/0507019 hep-ph/1101.6008 hep-ph/0611109 Nucl-th/1205.2396 Most theories predict RAA(b e) > RAA (ce) Let’s find out!

  4. Silicon Vertex Tracker e Life time (ct) D0 : 123 mm B0 : 464 mm Layer 3 e+ DCA e- Layer 2 D Beryliumbeampipe p p Layer 1 B Layer 0 e Barrel 3 Barrel 2 Barrel 1 Barrel 0 Barrel 0 Barrel 1 Barrel 2 Barrel 3 VTX: Silicon Barrels ~ 2p Main Goal

  5. PHENIX-VTX in Action at RHIC VTX in Run 2012:p+p at 200 GeV VTX in Run 2011:Au+Au at 200 GeV Primary Vertex: BBC vs VTX Data: AuAu at 200 GeV y (cm) Beam size s (beam) ~ 90 um x (cm)

  6. Conversion Electron Background Subtraction Layer 3 Layer 2 Layer 1 Layer 0 • - Challenge in the DCA measurement of single electrons is the Conversion Electron Background (CEB). • Most conversions happen in the outer layers (total radiation length = 12 % (B0: 1.3%, B1: 1.3%, B2:4.7% and B3: 4.7%). They are suppressed by requiring a hit in inner silicon layer B0.

  7. Conversion Electron Background Subtraction • - Challenge in the DCA measurement of single electrons is the Conversion Electron Background (CEB). • Most conversions happen in the outer layers (total radiation length = 12 % (B0: 1.3%, B1: 1.3%, B2:4.7% and B3: 4.7%). They are suppressed by requiring a hit in inner silicon layer B0. Associated Hit • Conversions in the beam pipe and B0, and Dalitz are suppressed by rejecting electron tracks with a nearby hit : Conversion Tag and Veto. Hit by track Random hit  DCA Conversion Tag B-field

  8. Conversion Electron Background Subtraction Fraction of HF electron after conversion Veto RHF = eHF/einc = eHF/(eHF+ ePH) • - Challenge in the DCA measurement of single electrons is the Conversion Electron Background (CEB). • Most conversions happen in the outer layers (total radiation length = 12 % (B0: 1.3%, B1: 1.3%, B2:4.7% and B3: 4.7%). They are suppressed by requiring a hit in inner silicon layer B0. • Conversions in the beam pipe and B0, and Dalitz are suppressed by rejecting electron tracks with a nearby hit : Conversion Tag and Veto. • Yield of the remaining conversions and Dalitz are estimated using the veto efficiency. 90% heavy flavor e Photonic BG is small after conversion VETO

  9. HF Invariant Yield in Au + Au • Using VTX to tag Dalitz and conversion electrons, we measure the heavy flavor (HF) electron spectra Run 2011 HF spectrum consistent with previously publishedHF byPHENIX

  10. Decomposition of the DCA Distributions -VTX provides another new capability: • Measure distance of closest approach to separate charm and bottom components of heavy flavor spectra - Charm to bottom ratio is obtained from the fit to the DCA distribution of measured electrons: • Charm and Bottom events generated by PYTHIA are convoluted with DCA resolution to obtained expected DCA distribution shapes.

  11. Distance of Closest Approach (DCA) Raw DCA distributions for charged hadrons and electronsp+p and Au+Au MB at 200 GeV Note: hadron contamination for electron DCA distributions is not subtracted in these plots

  12. Electron Distance of Closest Approach (DCA)

  13. Electron Distance of Closest Approach (DCA)

  14. Electron Distance of Closest Approach (DCA)

  15. Electron Distance of Closest Approach (DCA)

  16. Electron Distance of Closest Approach (DCA)

  17. Electron Distance of Closest Approach (DCA)

  18. Electron Distance of Closest Approach (DCA)

  19. Electron Distance of Closest Approach (DCA)

  20. Electron Distance of Closest Approach (DCA) c/(b+c) = 0.92 ± 0.02

  21. Electron Distance of Closest Approach (DCA) c/(b+c) = 0.81 ± 0.05

  22. Electron Distance of Closest Approach (DCA) c/(b+c) = 0.78 ± 0.06

  23. Results: Bottom Production in p+p 200 GeV First direct measurements of bottom production in p+p at RHIC From Fit of the DCA distribution

  24. Results: Bottom Production in p+p 200 GeV VTX direct measurement of b/b+c using DCA confirms published results using e-h correlation From Fit of the DCA distribution PHENIX Publisheddata agree With new data FONLLagree with data

  25. Results: Bottom Production in p+p 200 GeV First direct measurement of bottom production in p+p at RHIC From Fit of the DCA distribution STAR indirect measurement consistent with our data

  26. Results: Bottom Production in Au+Au 200 GeV First direct measurement of bottom production in Au+Au at RHIC From Fit of the DCA distribution

  27. Results: Bottom Production in Au+Au and p+p be /(be+ ce) in 200 GeV Au+Au vs p+p From Fit of the DCA distribution

  28. p+p: b/(b+c) Fitted by FONNL

  29. RAA of Bottom Extraction x RAA (be) =

  30. RAA of Bottom Extraction x RAA (be) =

  31. RAA of Bottom Extraction x RAA (be) =

  32. RAA of Bottom Extraction x RAA (be) =

  33. Nuclear Modification of Charm RAA (ce) Au+Au centrality: Min-Bias

  34. Nuclear Modification of Charm and Bottom RAA (be) < RAA (ce) No simple mass hierarchy in heavy flavor

  35. Summary • First measurements of Charm and Bottom separately in heavy ion collisions at RHIC achieved • In p+p, FONLL prediction of b/(b+c) agrees with the data • In Au+Au, RAA(be) is strongly suppressed • Most theory predictions of RAA(be) > RAA(ce) are not supported by our data PHENIX-VTX opens new era of heavy flavor physics at RHIC

  36. Auxiliary Slides 1/3/2020 rachid.nouicer@bnl.gov

  37. Distance of Closest Approach (DCA) Raw DCA distributions for charged hadrons and electronsp+p at 200 GeV Note: hadron contamination for electron DCA distributions is not subtracted in these plots

  38. Results: Bottom Production in Au+Au 200 GeV First direct measurements of bottom production in Au+Au at RHIC be /(be+ ce) in 200 GeV Au+Au vs Centrality From Fit of the DCA distribution Au+Au : 0-10% Au+Au : 10-60%

  39. Nuclear Modification of Charm RAA (ce) Charm (ce) is less suppressed than π0

  40. Results: RAA of Bottom and Charm Separately RAA of Bottom, Charm and published eHF in Au+Au MB Au+Au centrality: Min-Bias

  41. Distance of Closest Approach (DCA): Au+Au s(DCA) ~ 70 um

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