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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 GeV A. • 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. • 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 is powerful tool 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. 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

  5. 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 and bottom) S/N>1 @pt>2GeV/c

  6. 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

  7. 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.

  8. 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%)

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

  10. bottom fraction in non-photonic electron • The result is consistent with FONLL

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

  12. 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

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

  14. 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!

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

  16. tag D0K-p+ with electron tag D0K-p+p0 decay channel reconstruct Summary of p+p@200GeV results • non-photonic electron spectra was obtained in p+p@200GeV. • data/FONLL~1.7 • 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. • b->e/c->e ~1 @ pt~3GeV/c • Cross sections of charm and bottom were obtained from di-electron in p+p collisions at √s =200GeV. • charm and bottom cross sections from e+e- and c,be agree On going issues in p+p@200GeV • Direct reconstruction in D0K-p+p0 and D0K-p+ channels. • - clear peak has been obtained. • e-m correlation

  17. 4Measurementofdi-electron(Au+Au@200GeV) arXiv:0706.3034 c ce e dominant Cocktail agrees with data points@1.2<Mee<2.8.

  18. MB 0%~ ~92% p+p 5 non-photonic electron (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

  19. Nuclear Modification Factor: RAA PHENIX PRL98 173301 (2007) Djordjevic, PLB632 81 (2006) large suppression at high pt • Radiative energy loss • does not describe!. • dead cone effect

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

  21. PRELIMINARY minimum-bias Rapp & van Hees, PRC 71, 034907 (2005) Run-7 Run-4 V2 of non-photonic electron • large v2 has been observed charm flow new result suggest significant v2 at high pt bottom also flow? To reproduce suppression pattern & v2, small τ and/or DHQ are required (Rapp&van Hees, Moore and Teaney) h/s ~(1.3-2)/4p quantum limit

  22. 6 Summary • di-electron spectra was obtained in Au+Au@200GeV • non-photonic electron spectra was obtained in Au+Au@200GeV • large suppression pattern@high pt and large v2 was observed.  charm lose large energy loss and flow in (s)QGP. & be/ce >~ 1 @ pt>~3GeV/c (from p+p data) bottom lose large energy loss and flow in (s)QGP? • Model comparison suggests • smallτ and/or DHQ are required • η/s is very small, near quantum bound.

  23. PRELIMINARY minimum-bias p0RAA dependence on density-weighted average path length 0 – 20%: 3 < pTtrig< 6 GeV/c & 0.15 < pTasso< 1 GeV/c Rapp & van Hees, PRC 71, 034907 (2005) ? STAR Preliminary Run-7 Run-4 Outlook • more high pt v2 ? • electron –hadron correlation at Au+Au@200GeV ? • RAA dependence on path length ? • Silicon vertex detector

  24. back up

  25. 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

  26. 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

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

  28. tag D0K-p+ with electron tag reconstruct P.Shukla [poster] electron tag reduce combinatorial background • observe D0 peak • cross section of D is coming up

  29. 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

  30. 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

  31. 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 31

  32. Method I • Tune cocktail to PHENIX measured hadrons • Subtract cocktail • Extract cross section in multi steps as in ppg065 • A. dsigma_ee/dy(1.1<Mee<2.5; in ideal PHENIX acceptance) This is what directly measured. Only systematic error in the data and Statistical data present. • A1. Extrapolate to 0<M<5 GeV; However, since ds/dy(1.1<M<2.5) is a very tiny fraction of dsigma/dy(0<M), I would rather not mention about it. • B. dsimga_ee/dy(1.1<Mee<2.5; |ye|<0.35)This is when two arm acceptance of PHENIX is corrected. Since the two arm nature is corrected, this is something a theorist can easily calculate.(now acceptance error is involved) • C. dsimga/dy of ccbar (now PYTHIA error is involved: kt, pdf’s and branching ratio because we go from electrons to charm) • D. sigma(ccbar) total (now add error for rapidity distribution) • In the paper we mention only A., C. and D. for simplicity • A. is calculated from the data, C. and D. are derived in the procedure explained in the next slide

  33. Method II • Tune cocktail to PHENIX measured hadrons • Subtract cocktail • Fit p0*charm + p1*bottom + drell yan • Charm cross section = 567 mb (ppg065) • Beauty cross section = 3.77 mb (Claus Jaroceck and commonly used in single electron analysis) • Drell Yan = 0.040 mb and scaled to NLO calculations from Werner Vogelsang • DY (from PYTHIA) + p0*charm +p1*bottom •     p0           9.13960e-01 ± 8.24258e-02 • p1           1.06418e+00 ± 7.13970e-01 • DY (scaling Pythia to Werner’s calculations for M>4GeV) + p0*charm +p1*bottomQ/2 •     p0           9.08741e-01 ± 8.25467e-02 •     p1           1.14892e+00 ± 7.17499e-01 Q •     p0           8.97103e-01 ± 8.25275e-02 •     p1           1.24826e+00 ± 7.17928e-01 Q*2 •     p0           9.09590e-01 ± 8.25467e-02 •     p1           1.13538e+00 ± 7.17499e-01

  34. 50% ce, be spectra # of non-photnic electron in b/(b+c)  PPG65 spectra sys error of # of non-photnic electron 100%correlation sys error of PPG65 enlarge sys error of bottom non-photonic electron (total>b) 90% C.L

  35. PYTHIA  EvtGen  PISA Produce D (B) products Decay D (B) products Simulate detector response B0 b B0 b Bs+ Bs+ bbar bbar EvtGen

  36. Unlike Cross Like Cross Unlike 4-body Cross subtraction • p0g g* e+e- e+e- Yield in 4p X External conversion removed with fV cut Foreground Background Subtracted Yield in acceptance Data: like Monte Carlo: Cross Like Cross Unlike Add all contributions from p0, h, h3p0