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Dilepton analysis status Run-10 Au+Au @ 200 GeV

Dilepton analysis status Run-10 Au+Au @ 200 GeV. Dmitry Kotov Victor Riabov Yuriy Riabov (PNPI). Event and track selection. Basic cuts. Dataset: Run-10 Au+Au @ 200 GeV (pro.84), run#300105-310354. Cuts: DC deadmap (heavy-light meeting, 01/27/2011); Track quality: 31 || 51 || 63;

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Dilepton analysis status Run-10 Au+Au @ 200 GeV

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  1. Dilepton analysis status Run-10 Au+Au @ 200 GeV Dmitry Kotov Victor Riabov Yuriy Riabov (PNPI)

  2. Event and track selection. Basic cuts. Dataset: Run-10 Au+Au @ 200 GeV (pro.84), run#300105-310354 • Cuts: • DC deadmap (heavy-light meeting, 01/27/2011); • Track quality: 31 || 51 || 63; • |bbcvertex| < 20 cm; • Trigger: • BBCLL1(>1 tubes) || BBCLL1(>1 tubes) narrowvtx; • pT of unidentified track: 0.2 < pT < 10 GeV/c; • |zed| < 75 cm; • Ghost rejection for pairs (AN673, AN694): • if ( fabs(dzed)<6.0 && fabs( dphi - (0.13*dalpha) ) < 0.015 ) return false; if ( fabs( dphi - (0.04*dalpha) ) < 0.015 ) return false; if ( fabs( dphi - (-0.065*dalpha) ) < 0.015 ) return false; • Cut for central support of DC and RICH (AN926).

  3. DC dead map (I) DCE before DCE after Alpha Side0 8X1 9X2 6X2, 7X2 Side1 8X1 board

  4. DC dead map (II) DCW after DCW before Alpha Side0 8X2 9X2 12X1X2 13X2 Side1 8X2 9X2 4X1X2 13X1X2 board

  5. eID cuts. • eID cuts: • n0 > 3; • chi2n <= 10; • disp < 5; • |dep| < 2; • Cut for RICH ghosts (AN840): • ( fabs(xphi[i] - xphi[j]) < 0.12 && fabs(xz[i]-xz[j]) < 25 ); • |emcsdphi_e| < 2 && |emcsdz_e| < 2; • Optional eID cuts: • |hbdsdphi| < 2.5 && |hbdsdz| < 2.5; • hbdcharge > 9, 12, 15, 21; • HBD EN2 removal: • 180 < atan(hbdy/hbdx) < 202.5 and hbdz > 0.

  6. EMCal matchings How to • Accumulate TH2F’s emcdphi vs zed, emcdz vs theta for e+/e-; • Slice into zed (theta) bins, Gaussian fit, extract centroids and sigmas; • Fit centroids and sigmas with p0(pT)+p1(pT)*zed+p2(pT)*zed2: • Except for the fit of emcdz mean: p0(pT) + p1(pT)*tan(zed); • Fit p0, p1, p2 with c0+c1/pT+c2/pT2 to remove pT dependence; • emcsdphi_e = (emcdphi – centroid(zed, pT))/sigma(zed, pT) • emcsdz_e = (emcdz – centroid(theta, pT))/sigma(theta, pT)

  7. Emcsdphi 1 sector, e+, +/- field, 0.24< pT (GeV/c) <0.26 Mean Mean Mean Mean Mean Remove z-dependence Remove z-dependence Sigma Sigma Sigma Sigma Sigma Sigma Remove pT dependence Remove pT dependence Remove pT dependence emcsdphi_e = (emcdphi –centroid(zed, pT)) /sigma(zed, pT) Mean Mean Sigma Sigma Sigma Sigma Sigma Sigma p0 p0 p0 p0 p0 p0 p0 p0 p0 p0 p0 p0 p0 p1 p1 p1 p1 p1 p1 p1 p1 p1 p1 p1 p1 25 pT bins, 8 EMCal sectors, 2 charges, 2 field orientations Makes up to 800 histos! p2 p2 p2 p2 p2 p2 p2 p2 p2 p2

  8. Emcsdz 1 sector, e+, +/- field, 0.24< pT (GeV/c) <0.26 Mean Sigma Remove z-dependence Remove pT dependence emcsdz_e = (emcdz –centroid(zed, pT)) /sigma(zed, pT) Mean Sigma p0 p0 p1 25 pT bins, 8 EMCal sectors, 2 charges, 2 field orientations Makes up to 800 histos! p1 p2

  9. Sigmalized variables pT range of parameterizations from 0.1 to 4.0-4.5 GeV/c e+ Emcsdphi, sector 1, +/- field e- Mean Mean Mean Mean Sigma Sigma Sigma Sigma Emcsdz, sector 1, +/- field pT (GeV/c) Mean Mean Sigma Sigma

  10. E/p ratio parameterizations • Accumulate TH2F’s E/p vs pT for e+/e- candidates; • Slice into pT bins, Gaussian fit, extract centroids and sigmas and: pT of the slice: 0.4 – 0.5 GeV/c dep = (E/p – mean(pT))/sigma(pT) dep means and sigmas vs pT (sector 4, +/- field) Mean, e+ Mean, e- Sigma, e+ Sigma, e- pT

  11. HBD matching for e-candidates HBD acceptance before hbd matching HBD acceptance after hbd matching phi phi zed zed “After” histo divided to “before” phi = atan (hbdy/hbdx) zed = hbdz phi • In some phi-zed regions the probablity to have matching is unexpectedly low (~0.1-0.2). Why? • Need to include this into simulation? zed

  12. Min bias invariant mass spectra. J/psi peaks. 20 cm, hbd matching, hbd charge>9 20 cm, hbd matching 20 cm 968.5±91.7 (9.4%) 621.5±53.4 (8.6%) 551.2±50.3 (10%) 20 cm, hbd matching, hbd charge>21 20 cm, hbd matching, hbd charge>15 20 cm, hbd matching, hbd charge>12 302.9±39.1 (13%) 503.4±48.3 (10%) 433.6±45.1 (10.4%)

  13. Phi and omega proto-peaks 20cm, hbd matching, hbd charge > 9 • There are hints of peaks from omega and phi decays near 0.78 and 1.01: • Invisible without HBD! • Barely visible with HBD matching (|hbdsdphi|<2.5 && |hbdsdz|<2.5); • Best option is HBD matching + hbdcharge > 9. • Further increase of hbdcharge cut (12, 15, 21) impairs the signal.

  14. Low Minv issue • How to improve FG behavior at low Minv < 0.3 GeV/c2; • Huge peak near Minv ~ 0 GeV/c2. • BG shape doesn’t fully agree with FG; Counts Red – BG (mixing) Black - FG Minv

  15. To do list • Further work with analysis cuts (phiV); • Need centrality recalibrator: • Do we have/can we use temporary centrality recalibrator?

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