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Measurement of charm and bottom production in RHIC-PHENIX

Measurement of charm and bottom production in RHIC-PHENIX. Yuhei Morino for the PHENIX collaboration CNS, University of Tokyo JSPS DC fellow. Freeze-out. Hadron gas. Hadronization. QGP. Pre-equilibrium. 1.Introduction. RHIC is for the study of extreme hot and dense matter.

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Measurement of charm and bottom production in RHIC-PHENIX

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  1. Measurement of charm and bottom production in RHIC-PHENIX Yuhei Morino for the PHENIX collaboration CNS, University of Tokyo JSPS DC fellow

  2. Freeze-out Hadron gas Hadronization QGP Pre-equilibrium 1.Introduction • RHIC is for the study of extreme hot and dense matter. • p+p, d+Au, Cu+Cu, Au+Au collision • √s = 22.4, 62, 130, 200 A GeV . • Heavy quarks (charm and bottom) are produced at only initial stage • good probe for studying property of the medium. • p+p collisions  base line study, pQCD test. • d+Au collisions  initial effect study. • Au+Au collisions  energy loss, flow? @ hot and dense matter

  3. Heavy quark measurement at PHENIX • lepton from semileptonic decay • large branching ratio • c and b mixture K+ p- (single&di) lepton measurement has been used for the study of heavy quark p+p ~ Au+Au collisions IN ADDITION At p+p (d+Au) collisions, direct measurement, e-h, e-m correlation can be used. important base line study. direct measurement • direct ID (invariant mass) • large combinatorial background

  4. 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 2 Measurement of non-photonic electron Inclusive electron ( g conversion, p daliz,etc and heavy quark ) Background subtraction Non-photonic electron (charm,bottom and minor background) S/N>1 @pt>2GeV/c

  5. Phys. Rev. Lett 97,252002 (2006) 3 electron from heavy flavor (p+p@200GeV) • Single electrons from heavy flavor (charm/bottom) decay are measured and compared with pQCD theory • FONLL pQCD calculation agree to the data within uncertainty. (Fixed Order plus Next to Leading Log pQCD) • scc= 567 ± 57(stat) ± 224(sys) mb

  6. bottom fraction in non-photonic electron be/ceis obtained via D e K (no PID) reconstruction • The result is consistent with FONLL • bottom component is dominant • at pt>3GeV/c c2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value) (0.5~5.0GeV)

  7. electron spectra from charm and bottom be = (non-photonic) X (be/(ce+be)) PRL, 97, 252002 (2006) charm bottom

  8. e- K- e+ ne Heavy quark measurement via di-electron e+e- pair arXiv:0802.0050 heavy quark is dominant source @mee >1.1GeV

  9. Di-electron from heavy quark cocktail calculations are subtracted from data • bottom, DY,subtraction •  charm signal !! • mass extrapolation (pQCD) • rapidity extrapolation (pQCD) c dominant b dominant After Drell-Yan subtracted, fit (a*charm+b*bottom) to the data. charm and bottom cross sections from e+e- and c,be agree!

  10. 4 electron from heavy flavor (d+Au@200GeV) strong modification has not been observed below 3GeV/c The yield at d+Au collisions looks like slightly enhanced nuclear anti-showing of bottom? However, there are large statistical uncertainty for d+Au data. The high statistics and low material d+Au data is already collected. initial effect for heavy flavor will be revealed.

  11. MB 0%~ ~92% p+p ５electron from heavy flavor(Au+Au@200GeV) PHENIX PRL98 173301 (2007) Heavy flavor electron compared to binary scaled p+p data (FONLL*1.71) Clear high pT suppression in central collisions

  12. Nuclear Modification Factor: RAA PHENIX PRL98 173301 (2007) large suppression at high pt large V2 is also observed

  13. Adil & Vitev, PLB 649(2007)139 Comparison with models be/ce>~1 @ pt>~3GeV/c bottom may also lose large energy in (s)QGP • pQCD radiative E-loss • langevin + D resonances • langevin +pQCD elastic • langevin + Tmatrix • alternative approaches • collisional dissociation • heavy baryon enhancement

  14. shear viscosity of the matter Rapp and Hees et al reproduce RAAand V2 simultaneously with langevin simulation  DHQx2pT ~ 4-6 Moore and Teaney calculate the relation of viscosity between diffusion constant.  DHQ/ (h/(e+P)) ~ 6 The shear viscosity of the matter is estimated by the above two theory. h/s ~(1.3-2)/4p near the quantum limit

  15. 6 Summary • non-photonic electron spectra was obtained in p+p@200GeV • be/(ce + be) has been studied in p+p collisions at √s =200GeV via e-h correlation. Cross section of bottom was obtained from electron spectra and be ratio • Cross sections of charm and bottom were obtained from di-electron in p+p collisions at √s =200GeV • High statistics d+Au@200GeV data is already collected. • non-photonic electron spectra was obtained in Au+Au@200GeV • large suppression pattern@high pt and large v2 was observed. • Model comparison suggests smallτ and/or DHQ are required • η/s is very small, near quantum bound.

  16. back up

  17. Yield(1.2<mee<2.8GeV)/Ncoll • No significant centrality dependence • consistent with PYTHIA & random cc scenarios 4Measurementofdi-electron(Au+Au@200GeV) arXiv:0706.3034 c ce e dominant

  18. 3 Measurement of di-electron(p+p@200GeV) p+p at √s = 200GeV p+p at √s = 200GeV • Material conversion pairs removed by analysis cut • Combinatorial background removed by mixed events • additional correlated background: • cross pairs from decays with four electrons in the final state • particles in same jet (low mass) • or back-to-back jet (high mass) • well understood from MC arXiv:0802.0050 arXiv:0802.0050

  19. 4Measurementofdi-electron(Au+Au@200GeV) arXiv:0706.3034 c ce e dominant Cocktail agrees with data points@1.2<Mee<2.8.

  20. total cross section of bottom total cross section of charm and bottom √s dependence of cross section with NLO pQCD agrees with data

  21. direct measurement: DKp, DKpp • direct ID(peak) • large combinatorial background K+ Meson D±,D0 Mass 1869(1865) GeV BR D0 --> K+p- 3.85 ± 0.10 % p- BR D0 --> K+p-p0 14.1 ± 0.10 % BR --> e+ +X 17.2(6.7) % Direct measurement of D meson

  22. D0K-p+p0 decay channel D0K-p+p0 reconstruction S.Butsyk[poster] large branching ratio(14.1%)

  23. tag D0K-p+ with electron tag reconstruct electron tag reduce combinatorial background • observe D0 peak • cross section of D is coming up

  24. Singnal and Background Photonic Electron • Photon Conversion Main photon source: p0 → gg In material: g → e+e- (Major contribution of photonic electron) • Dalitz decay of light neutral mesons p0 → g e+e- (Large contribution of photonic) • The other Dalitz decays are small contributions • Direct Photon (is estimated as very small contribution) • Heavy flavor electrons (the most of all non-photonic) • Weak Kaon decays Ke3: K± → p0 e±e (< 3% of non-photonic in pT > 1.0 GeV/c) • Vector Meson Decays w, , fJ → e+e-(< 2-3% of non-photonic in all pT.) Non-photonic Electron

  25. Consistency Check of Two Methods Both methods were checked each other Left top figure shows Converter/Cocktail ratio of photonic electrons Left bottom figure shows non-photon/photonic ratio

  26. Open Charm in p+p STAR vs. PHENIX PHENIX & STAR electron spectra both agree in shape with FONLL theoretical prediction Absolute scale is different by a factor of 2 26

  27. PHENIX experiment • PHENIX central arm: • |h| < 0.35 • Df = 2 x p/2 • p > 0.2 GeV/c • Charged particle tracking analysis using DC and PC → p • Electron identification • Ring Imaging Cherenkov detector (RICH) • Electro- Magnetic Calorimeter (EMC) → energy E RNXP detector was installed at RUN7 improve determination of reaction plane

  28. FONLL: FONLL b/(b+c) FONLL c/(b+c) FONLL c/(b+c) b contribution to non-photonic electron Phys.Rev.Lett 95 122001 • FONLL: Fixed Order plus Next to Leading Log pQCD calculation • Large uncertainty on c/b crossing 3 to 9 GeV/c Measurement of be/ce is key issue.

  29. Main uncertainty of ec and eb  • production ratios (D+/D0, Ds/D0 etc) c,b separation in non-photonic electron D0e+ K-(NO PID) reconstruction Ntag = Nunlike - N like • background subtraction(unlike-like) • photonic component • jet component tagging efficiency when trigger electron is detected, conditional probability of associate hadron detectionin PHENIX acc From data From simulation (PYTHIA and EvtGen) { decay component (~85%)kinematics e jet component (~15%)

  30. c2 /ndf 21.2/22 @b/(b+c)=0.26(obtained value) (0.5~5.0GeV) • tag efficiency of • charm increases as • electron pt • tag efficiency of • data gets near bottom ec edata eb c2 /ndf 18.7/22 @b/(b+c)=0.56(obtained value) (0.5~5.0GeV) count tagging efficiency (ec,eb,edata) c2 /ndf 28.5/22 @b/(b+c)=0.42(obtained value) (0.5~5.0GeV) reconstruction signal and simulation

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