DNP/JPS 1 The azimuthal anisotropy of electrons from heavy flavor decays in √S NN = 200 GeV Au- Au collisions by PHENIX Shingo Sakai for the PHENIX collaborations (Univ. of Tsukuba)

DNP/JPS2 Why heavy flavor v 2 ? (1)π,K,K 0 s,p,Λ, Ξ,d ( light quark->u,d,s ) v 2 scales approximately with the number of valence quark of hadrons -> indicate partonic level flow if charm quark flow - partonic level thermalization - high the early stage of collision (2) Heavy flavor energy loss - pT reflects energy loss - if heavy flavor energy loss is small, smaller high pT might be expected compared with light quarks v2 M. Djordjevic, M. Gyulassy, R. Vogt, S. Wicks. nucl-th/

DNP/JPS3 Heavy flavor PHENIX Elecron 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%) photonic non-photonic

DNP/JPS4 Electron v2 PHENIX e-e- Electron v 2 is measured by R.P. method R.P. --- determined with BBC Tracking (pT,φ) --- DC + PC electron ID --- RICH & EMCal dN/d(  -  ) = N (1 + 2v 2 obs cos(2(  -  ))) (E-p/p/sigma) distribution RICH B.G. After subtract B.G. Fig : Energy (EMcal) & momentum matching of electrons identified by RICH. Clear electron signals around E-p/p = 0

DNP/JPS5 Non-photonic electron v2 measurement converter method Separate non-photonic & photonic e v2 by using Non-converter run & converter run Non-converter ; N nc = N γ +N non-γ => (1+R NP )v2 nc = v2 γ + R NP v2 non-γ Converter ; N nc = R  *N γ +N non-γ => (R  +R NP ) v2 c = R  v2 γ + R NP v2 non-γ * R  -- ratio of electrons with & without converter v2 nc --- inclusive e v2 measured with non-converter run v2 c --- inclusive e v2 measured with converter run v2 γ --- photonic e v2, v2 non-γ --- non photonic e v2 cocktail method Determined photonic electron v2 with simulation Then subtract it from electron v2 measured with non-converter run v2 non-γ = {(1+R NP )v2 - v2 γ } }/R NP Run04: X=0.4% Run02: X=1.3% Non-pho./pho. (QM05 F. Kajihara)

DNP/JPS6 Inclusive electron & photonic electron v2 inclusive e v 2 photonic e v 2 Non photonic signal Photonic b.g. - inclusive electron v2 (pho. + non-pho.) & photonic electron v2 pT < 1.0 GeV/c --- converter method pT > 1.0 GeV/c --- cocktail method - inclusive electron v2 is smaller than photonic electron v2 - Above 1.0 GeV/c, non-photonic electron contribution is more than 50 % !

DNP/JPS7 Charm quark flow ? -pT dependence of non-photonic electron v2 after subtracting photonic electron from inclusive electron v2 -Compared with quark coalescence model prediction. D -> e v2 with/without charm quark flow (Greco, Ko, Rapp: PLB 595 (2004) 202) *Due to light quark has finite v2, D meson has non-zero v2 though charm quark v2 = 0 Below 2.0 GeV/c ; consistent with charm quark flow calculation Greco, Ko, Rapp: PLB 595 (2004) 202

DNP/JPS8 D v2 from non-photonic electron v2 (1) access D meson v2 from non-photonic electron v2 below 2 GeV/c (due to large error & uncertainty B meson contribution above 2 GeV/c) (1) Assume D meson v2 as; v2 D = a * f v2 (p T ) f v2 (pT) = pi v2 f v2 (pT) = kaon v2 f v2 (pT) = proton v2 f v2 (pT) = D v2 (y_T scailing) (2) Calculate D -> e (PYTHIA) (3) D v2 is given as weight to get e v2 (4) chi-squared test with “measured” non-photonic electron v2 below 2 GeV/c χ 2 = Σ{(v2 non-γ - v2 D->e )/σ v2 } 2 (3) Find chi-squared minimum of a experimentsimulation f v2 (pT) = pi v2 f v2 (pT) = kaon v2 f v2 (pT) = proton v2f v2 (pT) = D v2 (y_T scal.) chi2 a(%)

DNP/JPS9 D v2 from non-photonic electron v2 (2) -D meson v2 after scaling with chi2 minimum value (a chi2_mim ) for each D meson shape (f v2 (pT)) v2 D = a chi2_mim * f v2 (pT) f v2 (pT) = pi v2 f v2 (pT) = kaon v2 f v2 (pT) = proton v2 f v2 (pT) = D v2 (y_T scailing) -D (= a chi2_mim * f v2 (pT)) -> e v2 compared with “measured” non-photonic electron v2 D meson v2 after scaling with chi2 minimum value (a chi2_mim ) for each f v2 (pT)

DNP/JPS10 Simulation of B->e v2 D & B v2 (assume D & B v2 same) D -> e B -> e (B v2 high pT) B -> e (B v2 high pT ) - B meson v2 same as D meson v2 high pT high pT - Clear difference electron v2 from B & D -If B meson v2 is (1)Smaller v2 than D meson high pT (3) B->e overcome D->e around 3~4 GeV/c Non-photonic e v2 might be reduced. pTpT v2v2

DNP/JPS11 Conclusion Non-photonic electron v 2 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 p T Compare with PYTHIA calculation. D meson v scaled pion v 2 =>Indicate D meson v 2 is smaller than pion v 2 Non-photonic electron v 2 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 Access D meson v2 from non-photonic electron v2 assuming D meson v2 shape as pion, Kaon, proton & D meson from y_T scailing.

DNP/JPS12 Back up slides

DNP/JPS13 y_T scailing

DNP/JPS14 Photon Converter (Brass: 1.7% X 0 ) Yield of conversion electron can be determined by the radiation length (X 0 ) of material amount. We know precise X 0 of each detector material, but don’t the total effective value (+ air etc.). However, we can measure the yield of conversion electron by inserting of converter. Then, the photonic electron is subtracted from inclusive. Advantage is small systematic error even in low p T region. Photonic Subtraction -Converter Method N e Inclusive electron yield Material amounts:  0 1.1% 1.7% Dalitz : 0.8% X 0 equivalent 0 With converter Conversion in converter W/O converter 0.8% Non-photonic Conversion from known material ? % Photonic F. Kajihara (session CC 7)