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Upsilon and Chi_c Measurements in Heavy Ion Physics

This presentation by Kwangbok Lee from Korea University, delivered on November 22, 2010, delves into heavy ion physics, concentrating on measurements of Upsilon and Chi_c states in d+Au collisions. It outlines the conceptual framework of heavy ion collisions, including phenomena such as shadowing effects and nuclear absorption. The ongoing challenges in measuring charmonium and quarkonia suppression are discussed, alongside insights into Cold Nuclear Matter effects. The talk also considers future prospects and deeper analysis of quark-gluon plasma contributions to heavy ion interactions.

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Upsilon and Chi_c Measurements in Heavy Ion Physics

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  1. Heavy Ion physics and heavy quarkonia: focused on Upsilon and chi_c measurement Kwangbok Lee Korea University Kwangbok Lee - 22 Nov. 2010

  2. Outline • Heavy Ion physics - A + A collision -> J/psi, heavy quarkonia - p(d) + A collision (Cold nuclear matter) -> Shadowing effect, nuclear absorption, gluon saturation, initial state energy loss • Υmeasurement in d + Au collision (Preliminary) • ccmeasurement in d + Au collision (Challenging, ongoing) • Future prospect Kwangbok Lee - 22 Nov. 2010

  3. Heavy Ion physics present First Supervovae Galaxy & Star Formation Atom Formation He Formation WI & QED Separate Quark Gluon Plasma EW & QCD Separate (GUT) Big Bang The phase diagram of QCD matter History of the Universe Kwangbok Lee - 22 Nov. 2010

  4. Heavy Ion Collision 1. About to collide 4. Hadronize(Freeze out) 2. Collide 3. QGP Time Time The space-time diagram of a heavy ion collision Kwangbok Lee - 22 Nov. 2010

  5. SPS RHIC Energy Density J/psi suppression • Several scenarios may contribute: • Suppression by the color screening • Cold nuclear matter (CNM) effect • Regeneration effect Satz, hep-ph/0512217 Sequential J/ψ suppression by colour screening Charmonium system Kwangbok Lee - 22 Nov. 2010

  6. Quarkonia & Color deconfinement cc bb • Each quarkonium has different • binding radius. hep-ph/0609197v1 H. Satz hep-ph/0512217 Schematic of color screening • At RHIC, Υ3Smelts and the Υ2S is likely to melt, the Υ1S • is expected to survive. - S. Digal et.al., Phys. Lett. B 514 (2001) 57. • C-Y Wong, Phys. Rev. C 72 (2005) 034906. Kwangbok Lee - 22 Nov. 2010

  7. Cold Nuclear Matter (CNM) • Since, in p(d)A collisions, no hot and dense medium is expected to be created, • the matter created is called cold nuclear matter (CNM). • The CNM can provide the quantitative comparison to the measurement of A + A collision • so can provide a better understanding of the effects beyond CNM from hot and dense • nuclear matter. • CNM is an interesting matter itself. B B A B A B A A Schematic illustration of Au + Au collision Schematic illustration of d + Au collision Kwangbok Lee - 22 Nov. 2010

  8. low x high x Cold Nuclear Matter (CNM) Q2 = 1.69 GeV2 nDS • Shadowing model • Nuclear absorption • Initial state parton energy loss antishadowing HKN07 EKS98 EPS09 EPS08 shadowing X2 J/y Υ1S RGPb Υ1S J/y arXiv:0902.4154 Gluon density in different x Rapidity Kwangbok Lee - 22 Nov. 2010

  9. Nuclear modification factors Ncoll: number of binary (pp) collisions in one HI collision. • If the production of AA behaves like in pp, • RdAu = Rcp= 1 • If there is suppression, RdAu , Rcp< 1 Kwangbok Lee - 22 Nov. 2010

  10. Upsilon analysis • Run 8 (2008) d+Au data and Run 6 (2006) p+p data are used. • -> provide Upsilon cross section, σΥ and Upsilon nuclear modification factor, RdAu. • Physical backgrounds of Drell Yan, open charm and open beauty • are simulated and excluded. • (Recently, we got NLO Drell Yan calculation, so doing updates). Kwangbok Lee - 22 Nov. 2010

  11. PHENIX Muon arm Au d + - South North <y> ~ -1.7, x2 ~ 0.2 Gold going direction <y> ~ 1.7, x2 ~ 0.01 deuteron going direction thought to be in shadowing region Kwangbok Lee - 22 Nov. 2010

  12. Invariant mass distribution • Unlikesign event • Scaled Mixed event • Signal : Unlikesign – • Scaled Mixed event • Estimated combinatorial background by event mixing • There might be physical background in Upsilon mass region such as Drell-Yan, correlated open beauty and correlated open charm Kwangbok Lee - 22 Nov. 2010

  13. Drell-Yan process - simulation • DY events were embedded to real data to reflect more realistic environment. • Fit the reconstructed points with exponential function. • Shape and absolute value are extracted to fit the real data. Kwangbok Lee - 22 Nov. 2010

  14. Correlated open beauty - simulation • Pythia generation and generation by randomizing ϕ angle were considered. • Reconstructed through PHENIX simulation application chain. Kwangbok Lee - 22 Nov. 2010

  15. Correlated open charm - simulation • Did same procedure with correlated beauty estimation. • Charm isn’t estimated to affect Upsilon mass range much. Kwangbok Lee - 22 Nov. 2010

  16. Upsilon - simulation Kwangbok Lee - 22 Nov. 2010

  17. Fitting real data (p + p data set) • Drell Yan, correlated bottom, correlated charm and Upsilon • are considered to fit the data points. • Apply the shape and the absolute value of each component from simulation to • fit the data. Kwangbok Lee - 22 Nov. 2010

  18. Fitting real data (d + Au data set) • Drell Yan, correlated bottom, correlated charm and Upsilon • are considered to fit the data points. • Apply the shape and the absolute value of each component from simulation to • fit the data. Kwangbok Lee - 22 Nov. 2010

  19. Upsilon cross section in p + p • Shape matches CEM well (scaled down by factor of 2) BR*dσ/dy = 28.2±9.4(stat.)±4.8(syst.)pb, y [-2.2, -1.2] BR*dσ/dy = 31.1±8.7(stat.)±6.2(syst.)pb, y [1.2, 2.2] Kwangbok Lee - 22 Nov. 2010 19

  20. Upsilon RdAu in d+Au/p+p • Shows suppression at low x region RdAu = 0.84±0.34(stat.)±0.20(sys.), y [-2.2, -1.2] RdAu= 0.53±0.20(stat.)±0.16(sys.), y [1.2, 2.2] Kwangbok Lee - 22 Nov. 2010

  21. Another Upsilon measurements RdAu = 0.78+-0.28(stat.) +-0.20(sys.) at mid rapidity RAuAu < 0.64 at 90% C.L. at mid rapidity Kwangbok Lee - 22 Nov. 2010

  22. chi_c Analysis • Run8 d+Au collision and Run8 p+p collision are being analyzed. • Small MPC acceptance -> big uncertainties -> make the analysis hard. • Let me show the status. Kwangbok Lee - 22 Nov. 2010

  23. chi_c Analysis • Higher charmonium state(1P) than J/ψ(1S). • There are three states of chi_c. • Radiative decay channelcc -> J/ψ +γ-> μ+μ-(e+e-) + γ. • Rcc= (cc -> J/ψ +γ ) / (Inclusive J/ψ). • It would be a good tool to decouple the fraction of decay J/ψ and direct J/ψ. PDG 10’ Kwangbok Lee - 22 Nov. 2010

  24. How can we detect chi_c? γ d Au + Forward E.M. Calorimeter (MPC) 3.1 < |y| < 3.9 - South North MPC Muon arm Kwangbok Lee - 22 Nov. 2010

  25. MPC MPC PHENIX acceptance Backward & Forward Calorimetry South Muon Tracker North Muon Tracker EMCAL + Central Tracker 0 f coverage 2p EMCAL + Central Tracker -3 -2 -1 0 1 2 3 rapidity Kwangbok Lee - 22 Nov. 2010

  26. MPC acceptance by Pythia Kwangbok Lee - 22 Nov. 2010

  27. MPC photon energy distribution Low energy background !! Inclusive photon energy in MPC Chi_cdecay photon energy in MPC Kwangbok Lee - 22 Nov. 2010

  28. Kinematic cuts (2D) Single cc photon vs J/ψ rapidity Embedded cc photon vs J/ψ rapidity Kwangbok Lee - 22 Nov. 2010

  29. chi_c1 embedding simulation Foreground event Scaled mixed event Signal(Foreground – Mixed) Peak : 0.429 GeV Peak : 0.424 GeV North arm South Arm x-axis: μ+μ-γ(three particle correlated mass) – μ+μ-(dimuon mass) Kwangbok Lee - 22 Nov. 2010

  30. Fitting to real data (p + p data set) Foreground event Scaled mixed event Signal(Foreground – Mixed) Signal fitting with 2 Gaussians South Arm North arm Kwangbok Lee - 22 Nov. 2010

  31. Fitting to real data (d + Au data set) Foreground event Scaled mixed event Signal(Foreground – Mixed) • Peak is visible at small x region. • South MPC has large background. • Rccvaries from 0.8 ~ 1.5 depending the cc • distributions. • Rccvalues are still lager than expected. • Trying to figure out where the enhancement • comes from. dAu North Kwangbok Lee - 22 Nov. 2010

  32. Another chi_c measurement World average is about 0.3. But it has large fluctuations and uncertainties. Kwangbok Lee - 22 Nov. 2010

  33. prompt pm PHENIX upgrade • Silicon VTX, Silicon FVTX(LANL), • Muon trigger/RPC, etc. • Silicon Forward Vertex (FVTX). • -> Displaced vertex, Mass resolution. • First Drell-Yan from RHIC. • Separation of charm and beauty. Kwangbok Lee - 22 Nov. 2010

  34. Summary • Quarkonia measurement is a good probe to understand matter created in the heavy ion collision. • New Upsilon RdAu shows suppression in low x region and need to have theoretical comparison. • ccfeed down to J/y measurement is underway and will be important to decouple the cold nuclear matter effect and QGP state. Kwangbok Lee - 22 Nov. 2010

  35. Future • PHENIX detector upgrade is ongoing recently.. - Silicon VTX, Silicon FVTX(LANL), Muon trigger/RPC, etc. • Forward Silicon Vertex Detector (FVTX), led by the LANL group, will measure displaced vertices of the produced particles and improve the mass resolutions. • With the FVTX, we expect to separate the Drell-Yan process, open charm and openbeauty. Kwangbok Lee - 22 Nov. 2010

  36. Back up

  37. NLO Drell Yan estimation Kwangbok Lee - 22 Nov. 2010

  38. PHENIX Muon Piston Calorimeter Technology  ALICE(PHOS) PbWO4 avalanche photo diode readout Acceptance: 3.1 < η < 3.9, 0 < φ < 2π -3.7 < η < -3.1, 0 < φ < 2π Both detectors were installed for 2008 d-Au run. Assembly at UIUC PbWO4 + APD + Preamp MPC integrated in the piston of the muon spectrometer magnet. 38 Kwangbok Lee - 22 Nov. 2010 38

  39. Chi_c distribution andRcc σ = 1.5 Give different MPC acceptance of 3.8 % ~ 5.7 % ccrapidity Decay γ rapidity σ=flat • Rccvaries from 0.8 ~ 1.5 by the cc distributions. • Rccvalues are still lager than expected. • Trying to figure out where the enhancement comes from. Kwangbok Lee - 22 Nov. 2010

  40. Uncertainty summary Table. Uncertainty summary Kwangbok Lee - 22 Nov. 2010

  41. Invariant yield and cross sections Kwangbok Lee - 22 Nov. 2010

  42. Fit conditions Table. Summary of fit conditions Red: nominal setting, Blue: setting for systematic error estimation, Green: free parameter Kwangbok Lee - 22 Nov. 2010

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