1 / 18

Oleg Eyser Beau Meredith, Mickey Chiu, Matthias Perdekamp for the PHENIX Collaboration

DIFFRACTION 2010, Sep. 10-15, Otranto, Italy. Forward Di-Hadron Correlations in d+Au Collisions in PHENIX Searching for Gluon Saturation with the MPC. Oleg Eyser Beau Meredith, Mickey Chiu, Matthias Perdekamp for the PHENIX Collaboration. The gluon density at low x.

ely
Télécharger la présentation

Oleg Eyser Beau Meredith, Mickey Chiu, Matthias Perdekamp for the PHENIX Collaboration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DIFFRACTION 2010, Sep. 10-15, Otranto, Italy ForwardDi-Hadron Correlationsin d+Au Collisions in PHENIXSearching for Gluon Saturationwith the MPC Oleg Eyser Beau Meredith, Mickey Chiu, Matthias Perdekamp for the PHENIX Collaboration

  2. The gluon density at low x At small x we see an increase in gluons. There must be a kinematic region in which the gluon density reaches a saturation! Bremsstrahlung ~ asln(1/x) Recombination ~ asr

  3. Color Glass Condensate Qs2(x) Saturation Scale Forward Rapidity log x-1 Parton Gas d Au non-perturbative pT is balanced by gluons BKFL DGLAP Mid Rapidity log LQCD2 log Q2 The color glass condensate • Hadronic probe • Couple to gluons • High A • Higher parton densities • Asymmetric • Probe low x

  4. Signatures of the CGC p0 meson |h|<0.35 PHENIX CGC expectations Kharzeev, Kovchegov,,Tuchin, Phys.Rev.D68:094013,2003 increased h BRAHMSSTAR Gluon saturation is not the only explanation for the reduced yields. There may be other effects. PRL 97, 53203 (2006) PRL 98, 172302 (2007)

  5. d+Au in HIJING (A. Ogawa) Au Shadowing in jet correlations • pQCD 2→2 process = back-to-back di-jet • With shadowing in nucleus forward jet p d p mid-rapidity jet Vitev, hep-ph/0405068v2

  6. Mono-jets from the CGC • In the saturation regime the jet pT is balanced by many gluons. Kharzeev, Levin, McLerran (NPA748, 627) d Au dense gluon field • The gluon field is increased in central vs. peripheral collisions.

  7. The Nuclear Modification Factor • Correlation function Two-particle distribution Including two-particle acceptance • Conditional yield Number particle pairs per trigger particle Including acceptance & efficiency • Nuclear modification factor Conditional yield ratio d+A/p+p • Indicators of gluon saturation • IdA < 1 • Angular de-correlation of widths

  8. BRAHMS pp2pp PHENIX STAR Gluon Saturation @ RHIC d+Au vs p+p high-x valence quarks 0.25 < xq < 0.7 on low-x gluons 0.001 < xg < 0.1 Signatures of saturation • suppressions of nuclear modification factors • angular de-correlations of di-jet signals saturation is expected at x≈10-4

  9. Central Arms | η | < 0.35 Muon Arms 1.2 < | η | < 2.4 Muon Piston Calorimeter 3.1 < | η | < 3.9 Azimuthal Correlations in PHENIX • Trigger particle • Associate particle • Correlation • Near side peak • Away side peak Dj

  10. Azimuthal Correlations (prev.) • 2003 data • Trigger hadron from the muon arms • Correlated hadron from the central arm Phys.Rev.Lett.96:222301,2006

  11. Electromagnetic Calorimetersat rapidity 3.1 < |h| < 3.9 2.2 x 2.2 x 18 cm3 PbWO4 crystals 220 cm from nominal interaction point p0 merging effects pTmax ~ 2 GeV/c at outside ring For higher pT Reconstructed p0s for 7 GeV < E < 22 GeV Clusters for E > 15 GeV (~ 85% p0) The Muon Piston Calorimeters • gg invariant mass distribution • 11 GeV < E < 15 GeV • Signal pairs • Mixed event pairs • p0 yield

  12. peripheral to central Forward Di-jet Signal with Dh = 3.4 PHENIX Central region Side View p0 orclusters p0 or h+/- d Au xgluon ~ 10-2 Aueffective xgluon ~ 10-3

  13. Forward correlations at h = 3.4 PHENIX Central region Side View • Work in progress • Area of away-side peak represents conditional yield • No efficiency correction • No uncorrelated background yet • Conditional yields, widths not shown p0 orclusters d Au xgluon ~ 10-3 Aueffective xgluon ~ 10-4

  14. Forward correlations (minBias) • Trigger particle pT > 2 GeV/c • Associate particle pT > 0.875 GeV/c

  15. Forward correlations peripheral central Peripheral d+Au seems more similar to p+p Central d+Au shows a reduced yield, maybe broadening

  16. pT,trigger pT,associate

  17. pT,trigger pT,associate

  18. Summary • Central/forward di-hadron correlations • No significant broadening between d+Au vs pp • Reduced IdA in more central collisions • Model calculations are needed to understand this effect • Forward/forward di-hadron correlations • Qualitative indications of onset of gluon saturation hypothesis in reduced yields • Data also suggests width broadening • More work needed on uncorrelated background!

More Related