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Heavy flavor results from STAR and PHENIX

This presentation discusses heavy flavor physics, including direct D-meson reconstructions and low pT muon measurements, at the Relativistic Heavy Ion Collider (RHIC).

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Heavy flavor results from STAR and PHENIX

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  1. Heavy flavor results from STAR and PHENIX LijuanRuan (Brookhaven National Laboratory) Outline: • Introduction: why heavy flavor? • D, non-photonic muon and electron spectra in pp, dAu and AuAu: c,b total cross section • Nuclear modification factors and v2:flow pattern and collectivity • Nuclear modification factors: energy loss Lijuan Ruan (RHIC & AGS User Meeting)

  2. Why heavy flavor? Mb 4.8 GeV >> Tc, LQCD, Muds Mc 1.3 GeV • Higgs mass: electro-weak symmetry breaking. (current quark mass) • QCD mass: Chiral symmetry breaking. (constituent quark mass) • Heavy quark masses are not modified by QCD vacuum. Strong interactions do not affect them. • Important tool for studying properties of the hot-dense matter created at RHIC energy. Muller nucl-th/0404015 Lijuan Ruan (RHIC & AGS User Meeting)

  3. Heavy flavor physics • Physics goal at RHIC: Identify and study the properties of matter with partonic degrees of freedom (flavor, color, sound, temperature …) Lijuan Ruan (RHIC & AGS User Meeting)

  4. Heavy flavor measurements central arms --- electrons: DC (tracker), Ring Image Cherenkov (RICH), EMCal for(back)ward muon arms --- muons: muon tracker, muon identifier Advantages: -- low material budget, clean environ. -- central, forward/backward coverage D recon. from hadronic decay channels: TPC electrons: TPC, TPC+TOF, TPC+EMC low pT muons TPC+TOF hadronic decay Advantages: --reconstruction of D mesons -- large acceptance |φ|<2π,|η|<1.5 • c  e+ + anything (B.R.: 10.3%) • c  + + anything (B.R.: 9.5%) • D0 e+ + anything (B.R.: 6.9%) D0  + + anything (B.R.: 6.5%) - semileptonic decay Lijuan Ruan (RHIC & AGS User Meeting)

  5. Direct D-meson reconstructions D0 Phys. Rev. Lett. 94 (2005) S. Butyk (QM2008 poster) PHENIX Preliminary Year5 pp 200 GeV STAR Preliminary A. Shabetai, QM2008 Thanks to TPC acceptance at STAR  Reconstruct DK directly. Lijuan Ruan (RHIC & AGS User Meeting)

  6. Low pT muon measurements at STAR H.Liu et al., PLB639(2006)441 STAR: nucl-ex/0805.0364 Lijuan Ruan (RHIC & AGS User Meeting)

  7. Electron ID at STAR |1/-1|<0.03 STAR Collaboration, nucl-ex/0309012 STAR Collaboration, nucl-ex/0407006 γ conversion π0, η Dalitz decays Kaon decays ρωΦ vector meson decays heavy quark semi-leptonic decay others Single Electrons Spectra background signal γ conversion and π0Dalitz decays are the dominant sources. Non-photonic electron: 1-10 GeV/c (TPC+TOF+EMC) Combine the dE/dx from TPC and velocity from TOF: clean e from 0.3<pT<5 GeV/c Lijuan Ruan (RHIC & AGS User Meeting)

  8. Heavy flavor spectra at STAR STAR: nucl-ex/0805.0364 STAR: PRL98(2007)192301 STAR Preliminary STAR: low pT muons, D, intermediate to high pT electron measurement 4 independent measurements, consistent Cover 90% kinematical range of total charm cross section at mid-rapidity Lijuan Ruan (RHIC & AGS User Meeting)

  9. Converter method Cocktail method Ne Electron yield converter 0.8% 0.4% 1.7% With converter Photonic W/O converter Dalitz : 0.8% X0 equivalent radiation length Non-photonic 0 Material amounts: 0 Non-photonic electron measurement at PHENIX Inclusive electron ( g conversion, p daliz,etc and heavy quark ) Background subtraction Non-photonic electron (charm and bottom) Y. Morino, WWND2008 S/N>1 @pt>2GeV/c Lijuan Ruan (RHIC & AGS User Meeting)

  10. Heavy flavor spectra at PHENIX e+e- pair PHENIX:arXiv:0802.0050 c dominant b dominant PHENIX PRL98(2007)172301 PHENIX non-photonic electron: two independent method (converter and cocktail) 0.4-5 GeV/c to derive charm total cross section di-electron measurement: consistent with non-photonic e measurements. Lijuan Ruan (RHIC & AGS User Meeting)

  11. Charm cross-section PRL 94 (2005) • Charm total cross section follows roughly Nbin scaling from d+Au to minbias Au+Au to central Au+Au considering errors • signature of charm production exclusively at the initial impact • 2. STAR and PHENIX: self-consistent; STAR results ~ 2 times larger than PHENIX • Low material run in run8 dAu and pp at STAR  solve the puzzle. • 3. Upper limit of FONLL calculation: consistent with STAR measurements. Lijuan Ruan (RHIC & AGS User Meeting)

  12. total cross section of bottom Total cross section of bottom Y. Morino, QM2008 √s dependence of cross section with NLO pQCD agrees with data Lijuan Ruan (RHIC & AGS User Meeting)

  13. D* in jet and gluon splitting STAR Preliminary X. Dong QM2008 poster STAR Preliminary Data consistent with pQCD calculation for gluon splitting rate. Compare to NLO cal., gluon splitting to total charm production at RHIC is small.  put constraints on charm production mechanism Lijuan Ruan (RHIC & AGS User Meeting)

  14. Charm flow pattern: radial flow and v2 STAR: nucl-ex/0805.0364 Y. Zhang, QM2008 PRL, 98, 172301 (2007) D. Hornback, QM2008 STAR Preliminary • Tfo = 220 MeV (best fit) – freeze out earlier • <t> = 0.23 (best fit), <0.42 (1-) • favor moderate or small radial flow. • 2. Sizable v2  strong-interacting Quark Gluon Plasma Lijuan Ruan (RHIC & AGS User Meeting)

  15. RAA of non-photonic electrons STAR:PRL98(2007) 192301 • Non-photonic electrons show a similar magnitude of suppression as light hadrons. • No D and B spectra measurements at RHIC at high pT • What’s the real c and b contribution to single electrons? Lijuan Ruan (RHIC & AGS User Meeting)

  16. e-h correlations – bottom contribution G. Wang, QM2008 Y. Morino, QM2008 Extract bottom contribution from the data/simulation comparison Lijuan Ruan (RHIC & AGS User Meeting)

  17. e-h correlations – bottom contribution (be)/(ce+be) Y. Morino, QM2008 G. Wang, QM2008 A. Mischke, QM2008 non-photonic electron spectra has significant contribution from bottom. pT(e)~ 5GeV/c, 50% from beauty Lijuan Ruan (RHIC & AGS User Meeting)

  18. RAA of non-photonic electrons Y. Xu, DNP2007; P. Fachini, B. Mohanty, QM2008; L. Ruan WWND2006, HP2006 STAR:PRL98(2007) 192301 STAR: PRL97,152301(2006) Bottom energy loss, significantly as light flavor: no mass effect on partonic energy loss? heavy quark spectra steeper than calculated in the FONLL calculations? Common suppression of protons and pions: no color charge dependence of partonic energy loss? Lijuan Ruan (RHIC & AGS User Meeting)

  19. RAA of non-photonic electrons RUN4 RUN7 min.bias PHENIX:PRL98(2007)172301 Bottom energy loss? Bottom flow? collisional dissociation resonance excitation model relaxation time of heavy quark /s =(4/3-2)/4 sentitive the chemistry of QGP energy dependence of RAA Lijuan Ruan (RHIC & AGS User Meeting)

  20. e-h correlations – conical emission Trigger on NPE from heavy quark decays. G. Wang, QM2008 Au+Au 200 GeV Cu+Cu 200 GeV STAR Preliminary Double peaked structure on away side observed in e-h correlations Does heavy quark e-loss generate conical emission? 3 particle correlations? Lijuan Ruan (RHIC & AGS User Meeting)

  21. RAAin 200 GeV Cu+Cu collisions RAA for non-photonic e± RAA for p ±, Cu+Cu 200 GeV Non-photonic e± Cu+Cu 200 GeV 0-54% * R. Hollis, WWND 2007 STAR: PRL 98 (2007) 192301 PHENIX: PRL 98 (2007) 172301 • Consistent with ±RAA in Cu+Cu 200 GeV • Consistent with Au+Au 200 GeV data for similar Npart A. G. Knospe WWND2008 Lijuan Ruan (RHIC & AGS User Meeting)

  22. J/-hadron correlation in p+p (S+B)/B: 54/14 5.4s • No significant near side J/-hadron azimuthal angle correlation • Constrain B meson’s contribution to J/ yield • Z. Tang, QM2008 Lijuan Ruan (RHIC & AGS User Meeting)

  23. Summary • Charm total cross section follows Nbin scaling from p+p, d+Au to minbias Au+Au to central Au+Au  charm produced via initial parton fusion • Different charm radial flow pattern is observed  charm seems to freeze out earlier. • Sizable non-photonic electron v2 is observed  charm elliptic flow • consistent with partonic collectivity • The suppression of non-photonic electron coming from (c, b) RAA at high pT observed in central Au+Au collisions, as strong as light flavor (u,d,s)  Challenge to existing energy loss models Lijuan Ruan (RHIC & AGS User Meeting)

  24. Outlook Run8 p+p • low material run in run8 at STAR, solve the discrepancy between STAR and PHENIX: electron ID from TOF (5 trays) and EMC • Run9: TOF will cover 50-75% of TPC acceptance, DK up to 5 GeV/c  constrain the energy loss mechanisms. Lijuan Ruan (RHIC & AGS User Meeting)

  25. STAR and PHENIX upgrades: inner tracker PHENIX: leptons from D and B decay, separately. STAR HFT: Direct reconstruction of charmed hadrons (mesons and baryons) using secondary decay vertices; Measure leptons from B decay Lijuan Ruan (RHIC & AGS User Meeting)

  26. Backup Lijuan Ruan (RHIC & AGS User Meeting)

  27. Phys. Rev. Lett 97,252002 (2006) non-photonic electron (p+p@200GeV) • Single electrons from heavy flavor (charm/bottom) decay are measured and compared with pQCD theory • FONLL pQCD calculation agree with the data (Fixed Order plus Next to Leading Log pQCD) • scc= 567 ± 57(stat) ± 224(sys) mb Lijuan Ruan (RHIC & AGS User Meeting)

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