1 / 21

Michael L. Miller Yale University For the STAR Collaboration

Multiparticle Correlations and Charged Jet Studies in p+p , d+Au , and Au+Au Collisions at s NN =200 GeV. Michael L. Miller Yale University For the STAR Collaboration. Jet Properties at RHIC. Measure jets in “simple” system ( p+p ).

reid
Download Presentation

Michael L. Miller Yale University For the STAR 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. Multiparticle Correlations and Charged Jet Studies in p+p, d+Au, and Au+Au Collisions at sNN=200 GeV. Michael L. Miller Yale University For the STAR Collaboration

  2. Jet Properties at RHIC Measure jets in “simple” system (p+p). Use this information to measure jets in complex system (Au+Au).

  3. Particles from same jet are close in angle Select high-pT portion of event (pT>2 GeV) Py (GeV/c) Particles from di-jets are ~180 deg. apart -4 -3 -2 -1 0 1 2 3 4 Px (GeV/c) -4 -3 -2 -1 0 1 2 3 4 Jets in Au+Au: Angular Correlations

  4. Jets in p+p: Direct Identification • Cluster final state (charged!) hadrons from a common “parent” quark/gluon. • Reconstruct momentum of quark/gluon • Implemented, tested, using 4 jet-finding algorithms Remember: only charged particles!

  5. Raw STAR Preliminary Di-jet Angular Distributions • Increase jet pT, tighten di-jet peak • Measure Nuclear kT in d+Au

  6. <Total pT> (Arbitrary Units) Raw STAR Preliminary Raw STAR Preliminary Within lead jet Transverse region Within away side jet Jet-Event Shape and Size

  7. Slope depends on jet-algorithm Events with pT>4 GeV track All jets with at least one 2<pT<6 GeV track Raw STAR Preliminary “Fragmentation” of Charged Jets What about “Correlation” jets? Selecting Jets with large Fragmentation Bias!

  8. Leading particle is a good approximation of jet direction Defines the pQCD scale Defines jet pT of away-side partner! Mean trigger fragmentation What Does this Mean? • At high jet-pT, leading particle collinear with jet axis • Correlation jets: leading particle carries ~80% of reconstructed charged particle jet pT. Leading particle is easily related to jet pT

  9. p+p: Adler et al., PRL90:082302 (2003), STAR Jets In d+Au Collisions • No background subtraction • Central: top 20% of -3.8<η<-2.8 uncorrected multiplicity • underlying event: p+p< d+Au minbias < d+Au central • near-side: correlation strength and width similar • away-side: d+Au peak broader but with little centrality dependence Back-to-back jets are not suppressed in central d+Au

  10. Au+Au, p+p: Adler et al., PRL90:082302 (2003), STAR Jets In Least Violent Au+Au Collisions • Au+Au: Subtract background from combinatorics, flow • d+Au: no suppression in central collisions  use min. bias. • d+Au: subtract underlying event. “away side” jet: consistent in all 3 systems “Near side” jet: consistent in all 3 systems

  11. Au+Au, p+p: Adler et al., PRL90:082302 (2003), STAR Jets In Most Violent Au+Au Collisions • Au+Au: Subtract background from combinatorics, flow • d+Au: no suppression in central collisions  use min. bias. • d+Au: subtract underlying event. “away side” jet: p+p d+AuAu+Au “Near side” jet: consistent in all 3 systems

  12. Conclusions • p+p: pT>4 GeV particles are good approximation of jet direction, momentum • d+Au: no suppression of away-side jet in central collisions • Au+Au: strong suppression of away-side jet in central collisions. Combined: Strong back-to-back suppression in central Au+Au cannot be fully explained by initial state physics

  13. What’s Coming from STAR? • p+p: Run III data with E.M. Calorimeter 0<<1. Identified jets including 0. • d+Au: Same! • Au+Au: Run IV with expanded calorimeter and extensive high-pT triggered data. Measure vacuum, in-medium “fragmentation” functions!

  14. Backup slides

  15. The STAR Detector

  16. FTPCE ZDCW Au d Uncorrected FTPCE multiplicity minbias single deuteron spectator d+Au “Centrality” Tagging • FTPCE multiplicity: -3.8<h<-2.8 (Au fragmentation direction) • ZDCW: single deuteron spectator • FTPCE multiplicity: defines “centrality” in d+Au events

  17. Jet-Event Shape and Size <Total pT> (Arbitrary Units) Raw STAR Preliminary Within lead jet Transverse region Within away side jet

  18. Thick plasma (Baier et al.): Gluon Bremsstrahlung Thin plasma (Gyulassy et al.): • Strong dependence of energy loss on gluon density glue: • measure DE measure gluon density at early hot, dense phase Why Jets? Energy Loss in Dense Matter

  19. “Fragmentation” of Charged Jets How does the slope change as a function of jet pT? Fragmentation slope scales with jet pT beyond 6 GeV Raw STAR Preliminary

  20. “Fragmentation” of Charged Jets What fraction of (reconstructed) jet pT does each particle carry? Slope depends on jet-algorithm Raw STAR Preliminary

  21. Di-jet Angular Distributions Raw STAR Preliminary • Increase jet pT, tighten di-jet peak • Measure Nuclear kT in d+Au

More Related