Gang Wang, WWND Non-Photonic Electron-Hadron Correlations at RHIC Gang Wang (University of California, Los Angeles)

Gang Wang, WWND Outline  Motivation  Analysis procedure  Near-side contribution in p+p collisions  Away-side broadness in A+A collisions  Outlook

Gang Wang, WWND Conical Pattern in Conical Pattern in 2-Particle Correlations in Au+Au Collisions p T trig = GeV/c; p T asso = GeV/c Motivations Mark Horner (for STAR Collaboration): J. Phys. G: Nucl. Part. Phys. 34 (2007) S995 The away-side correlation structure in Au+Au is different than p+p or d+Au. PHENIX, PRC 78 (2008)

Gang Wang, WWND Conical Pattern in Conical Pattern in 2-Particle Correlations in Au+Au Collisions p T trig = GeV/c; p T asso = GeV/c Motivations Mark Horner (for STAR Collaboration): J. Phys. G: Nucl. Part. Phys. 34 (2007) S995 Further support by 3-particle correlations See STAR paper on 3-particle correlations at arXiv: v2 (accepted by PRL) Conical Pattern

Gang Wang, WWND Away Side in medium : How does B/D lose energy? Via conical emission? Conical Pattern in Conical Pattern in 2-Particle Correlations in Au+Au Collisions p T trig = GeV/c; p T asso = GeV/c Motivations Mark Horner (for STAR Collaboration): J. Phys. G: Nucl. Part. Phys. 34 (2007) S995 Near Side: what’s the contribution of B/D decay to the non- photonic electrons? trigger What if we trigger on non-photonic electrons?

Gang Wang, WWND Study of heavy flavor via non-photonic electrons D mesons have their directions well represented by the daughter electrons, above 1.5 GeV/c. Electrons from B decays can represent the B meson momentum direction well if p T > 3 GeV/c. PYTHIA

Gang Wang, WWND Time Projection Chamber (TPC) Barrel Electro-Magnetic Calorimeter (BEMC) Barrel Shower Maximum Detector (BSMD) Data Sample: At  s NN = 200 GeV, p+p collisions in run5/6 (2006), d+Au collisions in run8 (2008), Cu+Cu collisions in run5 (2005), Au+Au collisions in run7 (2007). Electron ID in STAR Purity dAu, CuCu, AuAu: above 98% for 3 < p T < 6 GeV/c p+p collisions: above 98% for 3 < p T < 6 GeV/c; 80% for 9 GeV/c.

Gang Wang, WWND Decay photon conversions    →   → e + e - in material Main background Dalitz decays    →  e + e - Direct photon conversions Small but could be significant at high p T Heavy flavor electrons D/B → e ± + X Weak Kaon decays K e3 : K ± →   e ± e 1 GeV/c Vector Meson Decays  J  → e + e - < 2-3% contribution in all p T Photonic electronNon-photonic electron Electron signal and background

Gang Wang, WWND Photonic Background The invariant masses of the OS and SS e-pairs have different distributions. Reconstructed photonic electron is the subtraction. Photonic electron is the reconstructed-photonic/ ε ε is the background reconstruction efficiency calculated from simulations. e-e-  e+e+ e-e- (assigned as primary track) (global track) (primary track) dca

Gang Wang, WWND All Tracks Inclusive electron Non-photonic electronPhotonic electron Reco-photonic electron =OppSign - combinatorics Not-reco-photonic electron =(1/eff-1)*(reco- photonic) Pass EID cuts Procedure to Extract the Signal of e-h Correlations Semi-inclusive electron Δφ non-pho = Δφ semi-incl + Δφ SameSign – (1/eff -1)*(Δφ OppSign – Δφ SameSign ) Each item has its own corresponding Δφ histogram. In case of low purity… – Δφ hadron

Gang Wang, WWND Near-Side contribution in p+p

Gang Wang, WWND Clear azim. correlation is observed around near and away side. Fitting measured dn/dφ distribution from B and D decays, we can estimate B decay contribution to non- photonic electron. Non-photonic e-h correlations in p+p 200GeV B D

Gang Wang, WWND Almost half-half B and D contributions to non- photonic e’s at 5.5 < p T < 9 GeV/c, and FONLL prediction is consistent with our data within errors. B contribution to non-photonic e in p+p 200GeV

Gang Wang, WWND R AA for non-photonic electron is consistent with hadron’s. This Indicate large energy loss not only charm quark but also bottom quark. Large bottom energy loss? With the measurements of pp and R AA, we can derive a relationship between R AA ec and R AA eb. non-γ e hadron

Gang Wang, WWND o R AA ec & R AA eb correlation together with models o Dominant uncertainty is normalization in R AA analysis o R AA eb < 1; B meson is also suppressed o prefer Dissociate and resonance model (large b energy loss) I: Djordjevic, Gyulassy, Vogt and Wicks, Phys. Lett. B 632 (2006) 81; dN g /dy = 1000 II: Adil and Vitev, Phys. Lett. B 649 (2007) 139 III: Hees, Mannarelli, Greco and Rapp, Phys. Rev. Lett. 100 (2008) STAR preliminary p T > 5 GeV/c R AA ec & R AA eb correlation

Gang Wang, WWND Summary I  Non-photonic e-h correlations have been measured in p+p collisions to retrieve B and D contributions to non- photonic electrons up to p T ~9 GeV/c.  Comparable B and D contributions for electron p T 5.5~9 GeV/c.  FONLL prediction and the e B /(e B +e D ) results are consistent with each other within errors.  The measured B/D ratio would imply considerable b quark energy loss in medium based on R AA measurement from central Au+Au collisions. One more measurement is needed: R AA eb, R AA ec or

Gang Wang, WWND Away-side broadness in A+A d+Au collisions serve as a reference of the cold nuclear matter…

Gang Wang, WWND Non-photonic e-h correlations in d+Au 200 GeV Non-photonic e-h azimuthal correlation is measured in one π range, and open markers are reflections. The away-side correlation can be well described by PYTHIA calculations for p+p. No medium effects seen here. 3 < p T trig < 6 GeV/c & 0.15 < p T asso < 0.5 GeV/c STAR Preliminary

Gang Wang, WWND about 40% non-flow or fluctuation (Gang Wang, Nucl. Phys. A 774 (2006) 515.) Non-photonic e-h correlations in Cu+Cu 200 GeV Upper limits of v 2 used are 60% of hadron v 2 values measured with the v 2 {EP} method (equivalent to v 2 {2}). 0 – 20%: 3 < p T trig < 6 GeV/c & 0.15 < p T asso < 0.5 GeV/c On the away side, there’s a broad structure or a possible double- hump feature, even before v 2 subtraction. PYTHIA fit has a big χ 2.

Gang Wang, WWND Possible interpretations The away side in e-h is similar to what has been observed in h-h correlations, and consistent with Mach Cone calculations etc. The charm jet deflection provides an alternative interpretation. 3 < p T trig < 6 GeV/c & 0.15 < p T asso < 0.5 GeV/c

Gang Wang, WWND Non-photonic e-h correlations in Au+Au 200 GeV Upper limits of v 2 used are 80% of hadron v 2 values measured with the v 2 {EP} method. Non-photonic e-h correlation is broadened on the away side. PYTHIA fit has a big χ 2. 0 – 20%: 3 < p T trig < 6 GeV/c & 0.15 < p T asso < 0.5 GeV/c STAR Preliminary

Gang Wang, WWND Non-photonic e-h correlations in PHENIX More statistics needed … Anne Sickles, DNP08 talk. Also see the talk after mine...

Gang Wang, WWND  Using the d+Au collision as a reference, t he shape of non- photonic e-h azimuthal correlation function is found to be modified in central Cu+Cu and Au+Au collisions due to the presence of the dense medium created in these collisions.  Away-side: Hint of a broad structure, similar shape to that from h-h correlations.  Induced by heavy quark interaction with the dense medium?  Quantitative measure and investigation of the nature of the possible conical emission pattern will require more statistics! DAQ1000 will help us there! Should try 3-particle correlations! Here demonstrated is the feasibility of the analysis on the jet-medium interaction tagged by a heavy quark. Summary II

Gang Wang, WWND Outlook Large associated particle yields on the near side leave open questions: collective medium excitation by heavy quarks? Momentum kick model, Cheuk-Yin Wong

Gang Wang, WWND Back up slides

Gang Wang, WWND HQ Production Mechanism Due to large mass, HQ productions are considered as point-like pQCD processes HQ is produced at the initial via leading gluon fusion, and sensitive to the gluon PDF NLO pQCD diagrams show that Q-Qbar could be not back-to-back in transverse plane We need to study this smearing effect with models      0    flavor creation gluon splitting

Gang Wang, WWND PYTHIA simulations B D For each p t bin, the non-photonic e-h correlations B_corr and D_corr are combined according to B’s and D’s relative contributions to the non- photonic electrons: (e B *B_corr + e D *D_corr) / (e B +e D ) Each pt bin is weighted with their relative yields, and then they are summed up.

Gang Wang, WWND Electron ID in STAR With BEMC and BSMD, the electron peak is enhanced in the energy loss distribution, and we obtain a very pure electron sample. Purity dAu, CuCu, AuAu: above 98% for 3 < p T < 6 GeV/c p+p collisions: above 98% for 3 < p T < 6 GeV/c; 80% for 9 GeV/c. calibrated Log(dE/dx)

Gang Wang, WWND PYTHIA simulations weighted with CuCu yields 3 < p T trig < 6 GeV/c & 0.15 < p T asso < 0.5 GeV/c Here we assume the B/D contribution in CuCu is similar to that in p+p. Even if they are not similar, we don’t expect the double-hump without a medium. B D

Gang Wang, WWND Electron ID in PHENIX Also see the talk after mine... PHENIX central arm coverage: –|  | < 0.35 –  = 2 x π/2 –p > 0.2 GeV/c –typical vertex selection: |z vtx | < 20 cm charged particle tracking analysis using DC and PC1 electron identification based on –Ring Imaging Cherenkov detector (RICH) –Electro-Magnetic Calorimeter (EMC)