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

SQM2006 (Shingo Sakai)2 2006/3/26 OutLine Motivation Method of electron v2 measurement from heavy flavor decay Results  Compare with model  B meson contribution  Expected D meson v2 Summary

SQM2006 (Shingo Sakai)3 2006/3/26 Why heavy flavor v 2 ? π,K,K 0 s,p,Λ, Ξ ; ( light quark->u,d,s ) v 2 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 the early stage of collision

SQM2006 (Shingo Sakai)4 2006/3/26 Heavy flavor 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%) photonic non-photonic

SQM2006 (Shingo Sakai)5 2006/3/26 Non-photonic electron v2 measurement converter method Measure inclusive electron v2 with/without converter Then separate non-photonic & photonic e v2 Non-converter ; N nc = N γ +N non-γ => (1+R NP )v2 nc = v2 γ + R NP v2 non-γ Converter ; N c = 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 nc - v2 γ } }/R NP Run04: X=0.4% Run02: X=1.3% Non-pho./pho. (QM05 F. Kajihara)

SQM2006 (Shingo Sakai)6 2006/3/26 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

SQM2006 (Shingo Sakai)7 2006/3/26 Inclusive electron v2 (in/out converter) inclusive electron v2 in / out converter clear difference between converter in / out converter in electron v2 include large photonic component

SQM2006 (Shingo Sakai)8 2006/3/26 Inclusive electron & photonic electron v2 inclusive e v 2 (w.o. converter) photonic e v 2 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

SQM2006 (Shingo Sakai)9 2006/3/26 Non-photonic electron v2 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 1230

SQM2006 (Shingo Sakai) /3/26 B meson contribution to non-γ.e. v2 D & B v2 - assume D & B v2 same - v2 ~ 0.6 pi v2 D -> e B -> e pTpT v2v2 Model predict B -> e v2 reduce non-photonic electron high pT e v2 from B meson is smeared due to large mass difference based on quark coalescence model c, b reso ; c,b get v2 by elastic scat. in QGP Hendrik, Greco, Rapp nucl-th/ w.o. B meson (c flow) w. B meson (c,b flow)

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

SQM2006 (Shingo Sakai) /3/26 Compare D v2 with other hadron v2 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) π, deuteron v2 --- PHENIX preliminary

SQM2006 (Shingo Sakai) /3/26 Summary 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 B meson contribution might be reduce non-photonic e high pT Estimate D meson v2 from non-photonic electron v2 assuming D meson v2 shape as pion, Kaon, proton.

SQM2006 (Shingo Sakai) /3/26 Backup slides

SQM2006 (Shingo Sakai) /3/26 Azimuthal anisotropy ｘ ｙ pｘpｘ pｙpｙ Initial spatial anisotropy Momentum space anisotropy of particle emission A powerful probe of the initial state of the high energy heavy ion collision Low p T  pressure gradient of early stage of collision High p T  parton energy loss in hot & dense medium dN/dφ ∝ N 0 (1+2v 2 cos(2φ))

SQM2006 (Shingo Sakai) /3/26 Converter method Separate non-photonic & photonic e v2 by using Non-converter run & converter run Non-converter ; N nc = N γ +N non-γ Converter ; N c = R  *N γ +N non-γ (1+R NP )v2 nc = v2 γ + R NP v2 non-γ (R  +R NP ) v2 c = R  v2 γ + R NP v2 non-γ v2 non-γ (non-photonic) & v2 γ (photonic) is “experimentally” determined ! R  --- ratio of electrons with & without converter (measured) R NP --- non-photonic/photonic ratio (measured) v2 nc --- inclusive e v2 measured with non-converter run (measured) v2 c --- inclusive e v2 measured with converter run (measured)

SQM2006 (Shingo Sakai) /3/26 Determined photonic electron v2 with simulation Then subtract it from electron v2 measured with non-converter run dN e /d  = dN pho.e /d  + dN non-pho.e /d  v2 non-γ = {(1+R NP ) v2 - v2 γ } } / R NP Cocktail method measured R NP --- non-photonic/photonic ratio experimentally determined v2 --- inclusive electron v2 (without converter) v2 γ --- photonic electron v2 calculated from pi0 (pion) v2 calculate measured