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ΔG Measurement with the Heavy Quark Production

ΔG Measurement with the Heavy Quark Production. Hiroki Sato Kyoto Univ./RIKEN PHENIX November Core. ΔG Status and probes for it Prediction of A LL in the PHENIX A LL uncertainties and ΔG sensitivity J/  e  pair single electron Reduction of electron background Summary.

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ΔG Measurement with the Heavy Quark Production

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  1. ΔGMeasurement with the Heavy Quark Production Hiroki Sato Kyoto Univ./RIKEN PHENIX November Core • ΔG Status and probes for it • Prediction of ALL in the PHENIX • ALL uncertainties and ΔG sensitivity • J/ • e pair • single electron • Reduction of electron background • Summary PHENIX November Core

  2. Status of ΔG Measurement quark spin gluon spin proton spin orbital angular moment ～0.3 1/2 = (1/2)+G+L+LG Polarized Deep Inelastic Scattering ΔG Altarelli. et.al (1997)Q2= E155(1999) Q2=5GeV2 SMC(1997) Q2=10GeV2 Large uncertainty for indirect measurement Direct measurement with polarized p-p collisions（RHIC） PHENIX November Core

  3. Gluon Compton High-pT prompt  Charmonium Production e+e-, +- Open Heavy Quark Production e+e-, +- ,e high-pT single e, eD, D simulation ALL G(x) ? Probes for ΔG Measurement Experiment PHENIX November Core

  4. Simulations • Purposes • ALL expectation with PHENIX using some models of G(GS-A,B,and C) • Yield and background study → estimation of statistical and systematic errors. • PYTHIA 5.7 with GRV94-LO and JETSET 7.3 for event generation. • s=200GeV • Simple acceptance cut (||<0.35 for Central Arms and 1.1<||<2.3 for Muon Arms) • normalization to 32 or 320pb-1 PHENIX November Core

  5. ALLpp→bbＸ ALL μ e ALL Prediction at PHENIX T.Gehmann and W.J.Stirling(1995) M.Karliner and R.W.Robinett(1993) aLL ΔG（ｘ） 1.71 1.63 1.02 1.5 2 5 x cos* GRV-94 LO for unpol.PDF GS-A GS-B GS-C Me(GeV) PHENIX November Core

  6. ALL Experimental Errors PB1,2Beam Polarization　～　0.7(RHIC) N++（N+－）Number of events L++（L+－）Luminosity • Statistical Error • Systematic Errors • PB１,2→ ALL/ALL ~20% • (L+－/L++) → ALL~10ｰ4 • Nbg/Nsig ,ALLbg +‐: Beam Helicity PHENIX November Core

  7. Dimuons 320pb-1 s=200GeV pT()>2GeV/c J/ （color singlet model） Yield per Bin(0.2GeV/c2) bottom /K M(GeV/c2) NJ/(pT>2GeV)~120k events →ALLJ/(stat.)~ 0.006 N/K/NJ/~ 0.15 ALL/K ~0.007 → ALL J/(syst.)~0.001 ALLJ/ production mechanism of the charmonium G PHENIX November Core

  8. e pairs 320pb-1 s=200GeV pTe,pT>1GeV/c total _ cc→e /K→e Yield per 1GeV/c2 _ bb→e • background of electrons (0Dalitz decay and  conversion) can be reduced • b/c separation is under studying → important because ALL is different Meμ Me(GeV/c2) Me(GeV/c2) Nbb→eμ~120k events→ ALL(stat.)~ 0.006 Ncc→eμ~100k events ALL(syst.)~0.006 N/K→eμ~60k events Sensitive enough to distinguish GS-A,B and C PHENIX November Core

  9. bbe (pTe,pT >1GeV/c) X2 P(GeV/c) e pairsxregion X2 X1 Central Arm ｂ→e proton x1P ｂ→ x2P Muon Arm Correlation is small because of decay kinematics PHENIX November Core

  10. bbe (pTe,pT >1GeV/c) ALL Stat. Error 0.031 0.014 0.012 0.014 0.017 GS-A GS-B GS-C e pairs sensitivity 320pb-1 s=200GeV Background reduction  • Smaller systematic error • Larger statistics with low pT events Meμ Systematic error is comparable to statistical error PHENIX November Core

  11. pTe>1GeV/c 0->eX Assuming MVD efficiency is 90% 0 Dalitz reduction with the isolation cut with MVD • Another charged particle (pT>10MeV) in the cone of an electron → regard it as a 0 e+ or e- cc->eX 85% reduction can be achieved by the 10 degree cone cut for pTe>1GeV/c Detector simulation is needed for more realistic study PHENIX November Core

  12. 2229 601 1214 487  conversion reduction Akiba, 1997 Akiba 1997 • Comparable to Dalitz decay contribution • Origin • beam pipe (26%) - can be reduced by the isolation cut with MVD • MVD (53%) • inner barrel - reject 2-MIP events • outer barrel - require hits in the inner shell • MVD shell (21%) - require hits in MVD cm PHENIX November Core

  13. SingleElectrons Akiba,1996 Arbitrary unit With 32pb-1 luminosity (10% of full) and pTe>1GeV/c, • Charm 3.1M, min.bias 12M →1.8M(0 reduction) events • ALL(stat.)~0.001, ALL(syst.)~0.001 (ALL(GS-A)~ -0.04) →excellent measurement! 0 Dalitz charm pT in GeV/c PHENIX November Core

  14. Other probes • Di-electrons • Small Dalitz decay background • ~100k J/’s (pTe>0.4GeV/c) at 320pb-1 with the color-singlet model • open c/b is possible? • eD (D) pairs • identified with eK coincidence (peak in K invariant mass) • 31k events with 320pb-1 (pTe>0.4GeV/c) • strong charm ID → confirmation of open charm yield • Single muons • large statistics, but it’s crucial to reject decay hadrons before the nosecone. PHENIX November Core

  15. Summary and Conclusion • We can get many inputs on the gluon polarization from the asymmetry for heavy quarks using their (semi)leptonic decay channels. • Future Work • Separation of bottom/charm → important for e pairs (pTe,>1GeV/c). • Full simulation is needed for more realistic estimation of the Dalitz/conversion background reduction. • Electron trigger is needed → Ken Barish (UCR) and Matthias G.-Perdekamp(RBRC) work on this from spin side *with color octet model PHENIX November Core

  16. ...Backup slides... PHENIX November Core

  17. Muon Arm Performance • 1.1<||<2.4, absorber~10λint (pz cut~2GeV/c) • Detector acceptance~0.7 • Muon Tracking Chambers in Muon Magnet • 3 stations • x~100m →Δp/p~3% (@3~10GeV/c) • Muon Identifier • hadron rejection with 5 layers of Iarocci tubes and Steel Iarocci tube PHENIX November Core

  18. MuID Performance Test@KEK • Hadron rejection = Central Magnet MuID For 5GeV/c pions, 0.0050.04(South)= 210-4 < 210-3 (Decay before Central Magnet) Fraction of remainingp PHENIX November Core

  19. PHENIX Muon Simulation • Purpose • Estimation of signal and background • Evaluation of the detector response and reconstructionperformance • Procedure • Event generation(PYTHIA) p p s = 200GeV • Detector simulation Full GEANT • Reconstruction • Normalized to RHIC Luminosity • 32pb-1(year2000) • 320pb-1（year2001） PHENIX November Core

  20. Single  320pb-1 → • Contribution of  decay and b-quark is comparable for pT>6 GeV/c. • Uncertainty of the cross section of heavy quarks → measurement may be possible. c→ b→ PHENIX November Core

  21. Dielectrons Akiba 1996 PHENIX November Core

  22. PYTHIA charm PYTHIA bottom s=200GeV Open Heavy Quark Production 200b • PYTHIA(GRV-94LO) agrees with experimental data at lower energies (s < 50GeV) • Large theoretical uncertainties (30b<(cc)<3mb and 0.7b<(bb)<5b at s=200GeV) 0.7b 。 E789 PHENIX November Core

  23. Open heavy cross section II( higher s) • For b-quark production, PYTHIA agrees with D0 data within factor 2 ( at s=1.8TeV) • (pp→bbX),s=630GeV UA110.23.3b PYTHIA(GRV94-LO) 7.3b PHENIX November Core

  24. Invariant cross section of charged hadrons in pp collisions at s=200GeV Charged Hadron Production • PYTHIA(GRV94-LO) and UA1 data are consistent within factor two. PHENIX November Core

  25. PYTHIA / ratio • ~104 at pT=2GeV/c hadrons c→ b→ PHENIX November Core

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