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

1.Introduction RHIC is for the study of extreme hot and dense matter. Freeze-out Pre-equilibrium QGP Hadron gas Hadronization 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

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

2 Measurement of non-photonic electron Inclusive electron ( g conversion, p daliz,etc 　　and heavy quark ) Cocktail method Ne Electron yield Material amounts: 0 0.4% 1.7% Dalitz : 0.8% X0 equivalent radiation length With converter W/O converter 0.8% Non-photonic Photonic converter Converter method Background subtraction Non-photonic electron (charm,bottom and minor background) S/N>1 @pt>2GeV/c

3 electron from heavy flavor (p+p@200GeV) Phys. Rev. Lett 97,252002 (2006) 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

bottom fraction in non-photonic electron be/ce　is 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)

electron spectra from charm and bottom be = (non-photonic) X (be/(ce+be)) PRL, 97, 252002 (2006) charm bottom From bottom ratio in previous slide, electron spectra from charm and bottom are obtained by straight forward calculation. Black points are non-photonic electrons red points are electron from charm and blue points are electrons from bottom including cascade decay. From this b to e spectra, total cross section of bottom was obtained as this value. Lines are FONLL predictions. This figure is ratios of data over FONLL as a function pt. The ratio is about 2, which is reasonable value comparing with other experiments CDF, HERA.

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

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!

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.

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 MB p+p 0%~ ~92%

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

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 Adil & Vitev, PLB 649(2007)139 alternative approaches collisional dissociation heavy baryon enhancement

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

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.

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

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

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

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

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

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

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

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

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

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

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

b contribution to non-photonic electron FONLL: FONLL c/(b+c) FONLL b/(b+c) 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.

{ e 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%) Main uncertainty of ec and eb  production ratios (D+/D0, Ds/D0 etc)

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