Shingo Sakai for PHENIX Collaborations (Univ. of Tsukuba) The Azimuthal Anisotropy of Electrons from Heavy Flavor Decays in √sNN=200 GeV Au-Au Collisions at PHENIX Shingo Sakai for PHENIX Collaborations (Univ. of Tsukuba)

Method of electron v2 measurement from heavy flavor decay Results OutLine Motivation Method of electron v2 measurement from heavy flavor decay Results Compare with model B meson contribution Expected D meson v2 Summary 2006/3/26 SQM2006 (Shingo Sakai)

Why heavy flavor v2 ? π,K,K0s,p,Λ, Ξ ; ( light quark->u,d,s ) v2 scales approximately with the number of valence quark of hadrons -> indicate partonic level flow 　　　for u,d,s if charm quark also flow - partonic level thermalization - high density @ the early stage of collision The motivation of this measurement is two. One is heavy flavoe flow and the other is energy loss. The right figure shows the identified particle v2 scaled with number of quarks. These v2 are well scaled and that means the v2 already develop in partonic level. If charm quark flow it indicates that the partonic level thermalization and high density @ the early stage of collision. The bottom figure show the Raa for the quarks. The model predict that the heavy flavor energy loss is small compared with light quark. V2 is thought that the reflect energy loss therefore if heavy flavor energy loss is smaller, smaller v2 might be expected compared with light quarks v2 @ high pT. 2006/3/26 SQM2006 (Shingo Sakai)

Heavy flavor study @ PHENIX Electron sources charm decay beauty decay Dalitz decays Di-electron decays Photon conversions Kaon decays Thermal dileptons 　Subtract photonic electrons following methods “Cocktail subtraction” – calculation of “photonic” electron background from all known sources “Converter subtraction”– extraction of “photonic” electron background by special run with additional converter 　(brass, X = 1.7%) non-photonic photonic 2006/3/26 SQM2006 (Shingo Sakai)

Non-photonic electron v2 measurement converter method Measure inclusive electron v2 with/without converter Then separate non-photonic & photonic e v2 Non-converter ; Nnc = Nγ+Nnon-γ => (1+RNP)v2nc = v2γ + RNPv2non-γ Converter ; Nc = R *Nγ+Nnon-γ => (R +RNP) v2c = R v2γ + RNPv2non-γ R -- ratio of electrons with & without converter 　 v2nc --- inclusive e v2 measured with non-converter run 　 v2c --- inclusive e v2 measured with converter run v2γ --- photonic e v2, v2non-γ --- non photonic e v2 cocktail method Determined photonic electron v2 with simulation Then subtract it from electron v2 measured with non-converter run v2non-γ = {(1+RNP)v2nc - v2γ} }/RNP Non-pho./pho. Run04: X=0.4% Run02: X=1.3% (QM05 F. Kajihara) 2006/3/26 SQM2006 (Shingo Sakai)

Electron v2 measurement @ PHENIX Electron v2 is measured by R.P. method R.P. --- determined with BBC Tracking (pT,φ)　--- DC + PC electron ID --- RICH & EMCal dN/d(-) = N (1 + 2v2obscos(2(-))) eID @ RICH After subtract B.G. Energy (EMcal) & momentum matching B.G. Fig : Energy (EMcal) & momentum matching of electrons identified by RICH. Clear electron signals around E-p/p = 0 2006/3/26 SQM2006 (Shingo Sakai) (E-p/p/sigma) distribution

Inclusive electron v2 (in/out converter) clear difference between converter in / out converter in electron v2 include large photonic component 2006/3/26 SQM2006 (Shingo Sakai)

Inclusive electron & photonic electron v2 inclusive & photonic electron v2 pT < 1.0 GeV/c --- conv. method pT > 1.0 GeV/c --- simulation inclusive electron v2 is smaller than photonic electron v2 => non-photonic electron v2 is smaller than photonic electron v2 photonic e v2 inclusive e v2 (w.o. converter) Inclusive electron v2 2006/3/26 SQM2006 (Shingo Sakai)

Non-photonic electron v2 pT < 1.0 GeV/c --- conv. method pT > 1.0 GeV/c --- cock. method Indication for reduction of v2 at pT > 2 GeV/c ; Bottom contribution?? Compared with quark coalescence model prediction. with/without charm quark flow (Greco, Ko, Rapp: PLB 595 (2004) 202) Below 2.0 GeV/c ; consistent with charm quark flow model. indicate charm quark flow 1 2006/3/26 SQM2006 (Shingo Sakai) 1 2 3

B meson contribution to non-γ.e. v2 pT D & B v2 - assume D & B v2 same - v2 ~ 0.6 pi v2 v2 Hendrik, Greco, Rapp nucl-th/0508055 w.o. B meson (c flow) D -> e w. B meson (c,b flow) based on quark coalescence model c, b reso ; c,b get v2 by elastic scat. in QGP B -> e w. b meson w.o. b meson Model predict B -> e v2 reduce non-photonic electron v2 @ high pT e v2 from B meson is smeared due to large mass difference 2006/3/26 SQM2006 (Shingo Sakai)

D v2 estimate from non-γ e v2 Estimate D meson v2 with non-γe v2 (below 2.0 GeV/c) Assuming several v2 shape for D meson v2 Dv2(pT) = api * pi v2 Dv2(pT) = aK * kaon v2 Dv2(pT) = ap * proton v2 Calculate D -> e chi-squared test with “measured” non-photonic electron v2 find chi-squared minimum “a” for pi, K, p (api, aK and ap) D meson v2 Decay electron v2 Decay 2006/3/26 SQM2006 (Shingo Sakai)

Compare D v2 with other hadron v2 π, deuteron v2 --- PHENIX preliminary Π, deuteron v2 --- PHENIX preliminary 　expected D meson v2 from non-photonic electron v2 (pT < 2.0 GeV/c) smaller than pi v2 larger than Deuteron v2 (Mass D meson~ Mass Deuteron) 2006/3/26 SQM2006 (Shingo Sakai)

Non-photonic electron v2 from heavy flavor decays has been measured Summary Non-photonic electron v2 from heavy flavor decays has been measured with RHIC-PHENIX Compare with model calculations assuming charm flow or not Our result consistent with charm flow model below 2.0 GeV/c B meson contribution might be reduce non-photonic e v2 @ high pT Estimate D meson v2 from non-photonic electron v2 assuming D meson v2 shape as pion, Kaon, proton. 2006/3/26 SQM2006 (Shingo Sakai) Non-photonic electron v2 from heavy flavor decays has been measured with RHIC-PHENIX Compare with model calculations assuming charm flow or not =>Out result consistent with charm flow model at low pT Compare with PYTHIA calculation. D meson v2 --- scaled pion v2 =>Indicate D meson v2 is smaller than pion v2

Backup slides 2006/3/26 SQM2006 (Shingo Sakai)

Azimuthal anisotropy ｙ ｘ pｙ pｘ dN/dφ ∝ N0(1+2v2cos(2φ)) A powerful probe of the initial state of the high energy heavy ion collision Low pT pressure gradient of early stage of collision High pT parton energy loss in hot & dense medium Initial spatial anisotropy pｘ pｙ Spatial anisotropy Thermal equilibrium The azimuthal anisotropy of particle emission is sensitive to the early stages of system evolution Probe of jet quenching Hydro model Measurement of identified particle v2 give up much more Information of the collision dynamics Momentum space anisotropy of particle emission 　　dN/dφ ∝ N0(1+2v2cos(2φ)) 2006/3/26 SQM2006 (Shingo Sakai)

“experimentally” determined ! Converter method Separate non-photonic & photonic e v2 by using Non-converter run & converter run Non-converter ; Nnc = Nγ+Nnon-γ Converter ; Nc = R *Nγ+Nnon-γ (1+RNP)v2nc = v2γ + RNPv2non-γ (R +RNP) v2c = R v2γ + RNPv2non-γ v2non-γ(non-photonic) & v2γ(photonic) is “experimentally” determined ! R --- ratio of electrons with & without converter (measured) RNP --- non-photonic/photonic ratio (measured) v2nc --- inclusive e v2 measured with non-converter run (measured) 　v2c --- inclusive e v2 measured with converter run (measured) 2006/3/26 SQM2006 (Shingo Sakai)

Cocktail method Determined photonic electron v2 with simulation Then subtract it from electron v2 measured with non-converter run dNe/d = dNpho.e /d + dNnon-pho.e /d v2non-γ = {(1+RNP) v2 - v2γ} } / RNP measured measured calculate RNP --- non-photonic/photonic ratio experimentally determined v2 --- inclusive electron v2 (without converter) v2γ --- photonic electron v2 calculated from pi0 (pion) v2 From F. Kajihara 2006/3/26 SQM2006 (Shingo Sakai)