1 / 52

Jet Correlations at RHIC

Jet Correlations at RHIC. Jets from p+p and d+Au collisions Jets in Au+Au collisions High-p T jets: higher p T reach over Run-2 (2002) Low-p T jets: Exploration of the shape modification Cornucopia of other, newer avenues

neviah
Télécharger la présentation

Jet Correlations at RHIC

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. Jet Correlations at RHIC • Jets from p+p and d+Au collisions • Jets in Au+Au collisions • High-pT jets: higher pT reach over Run-2 (2002) • Low-pT jets: Exploration of the shape modification • Cornucopia of other, newer avenues • Is there a consistent picture of jet evolution from two-particle correlations in HIC? Nathan Grau, Iowa State University N. Grau Columbia University 10/17/05

  2. Phys. Rev. Lett. 91, 241803 (2003) p-pp0 + x p-pprompt + x data vs pQCD KKP Kretzer A Baseline for HIC Collisions: p+p NLO pQCD reproduces the measured single p0 production and prompt photons. Prompt photons – not from hadron decay N. Grau Columbia University 10/17/05

  3. PHENIX range A Surprise that pQCD Works? J. Owens CTEQ 2004 PHENIX measures at a similar xT ranges as Fermilab and finds good agreement with pQCD. Implication: no extra kT. kT: Transverse momentum of partons from confinement, gluon radiation at h=0 N. Grau Columbia University 10/17/05

  4. L. Apanasevich PRD 59 074007 (1999) kT for an Experimentalist • kT: Net pair pT • Experimentally determined by • Drell-Yan • Di-jet acoplanarity • Di-(prompt) photon correlations • Modified by initial and final state gluon radiation • Drell-Yan only initial state • Di-jets initial and final state N. Grau Columbia University 10/17/05

  5. Importance of kT for HIC • Jets good probe of QGP • Strong interaction with final state • Survives hadronization of the QGP • Sensitive to early times of the collision • Useful probe for multiple scattering/Energy Loss • Multiple collisions prior to hard scattering (Cronin effect) • Energy loss from gluon bremsstrahlung, multiple scattering, etc. N. Grau Columbia University 10/17/05

  6. Df Jet Measurement by Two-Particle Azimuthal Correlations Mixed events – corrects pair acceptance Total Elliptic flow C(Df) Near-angle Df = 0, jet Far-angle Df = p, di-jet Sum over all events  jets measured on a statistical basis Hard scattering Resonance decays Df (rad) N. Grau Columbia University 10/17/05

  7. pQCD & Two-Particle Correlations • Inclusive singles distributions described by pQCD • p+p baseline calibrated for single inclusive spectra • Jet rates are well calibrated • Correlations include non-perturbative effects • kT is partly due to confinement • fragmentation is non-perturbative • No curves overlay p+p correlation functions N. Grau Columbia University 10/17/05

  8. Correlations in p+p and d+Au N. Grau Columbia University 10/17/05

  9. = 21 GeV = 27.4 GeV p+A E683 E609 Strong Broadening at Lower Energies g+A and p+A offset due to an effect from jet reconstruction All data agree point-to-point when offset taken into account. A1/3 dependence in the g+A and p+A. Strong nuclear dependence on kT. A factor of 2 increase between p+p to p+Au at lower energy N. Grau Columbia University 10/17/05

  10. nucl-ex/0510021 Trigger 4-6 GeV/c PRL 91, 072304 (2003) Trigger 5-10 GeV/c Jet Correlations Resultsin p+p and d+Au Assume an isotropic background and two Gaussian distributions for the jet peaks. Extract the width of the Gaussian jet peaks. N. Grau Columbia University 10/17/05

  11. Jet Acoplanarity Difference Between p+p and d+Au J. Qiu, I. Vitev PLB 570 161 (2003) p0 – crosses p+/- – circles Multiple scattering model not inconsistent with the data. N. Grau Columbia University 10/17/05

  12. Why No Significant Difference Between p+p and d+Au? • “Intrinsic” kT larger than the kT due to multiple scattering. • Could it be recombination (Hwa and Yang)? • Shower (fragmented) partons recombining with the soft (radiated) background • Initially predicted factor of 2 increase in the near angle yield (R. Hwa, C.B. Yang: PRC 70,054902 (2004)) N. Grau Columbia University 10/17/05

  13. Ratio to p+p Hwa and Tan, nucl-th/0503060 Data favors no increased yield above p+p, but not inconsistent with reco Associated Particle Yields Trigger 5-10 GeV/c Measured yield in the gaussian near angle jet function N. Grau Columbia University 10/17/05

  14. Conclusions About Hard Scattering in d+Au Collisions • Two-particle correlations: d+Au like p+p • Lack of acoplanarity increase • Yields and acoplanarity are consistent with multiple scattering picture • And consistent with (modified) recombination picture. • Conclusion: Need more data. N. Grau Columbia University 10/17/05

  15. Au+Au Collisions Prior to QM2005 PRL 90 (2003) 082302 nucl-ex/0507004 Trigger 4-6 GeV/c Trigger 2.5-4 GeV/c N. Grau Columbia University 10/17/05

  16. Away-side Jet Modificationat High-pT in A+A N. Grau Columbia University 10/17/05

  17. Away-Side Jet at High pT STAR Preliminary H. Pei QM2005 poster D. Magestro QM2005 Trigger h 8-15 Associated h > 2 Above 7 GeV/c the (Gaussian?) away-side jet is evident. The beginning of jet tomography… N. Grau Columbia University 10/17/05

  18. Away-Side Widths From E-Loss I. Vitev hep-ph/0501255 IAA IAA Black – scattering of parent partons Red – gluons from energy loss. Able to fit IAA from STAR. N. Grau Columbia University 10/17/05

  19. Trigger 5-10 GeV/c J. Jin QM2005 poster 8 < pT(trig) < 15 GeV/c Extracted Away-Side Jet Widths at High pT Widths do not change between p+p and Au+Au?!? N. Grau Columbia University 10/17/05

  20. 8 < pT(trig) < 15 GeV/c Associated Yield Suppression • Yield decrease smoothly with centrality • IAA (with d+Au denominator) suppression! • Factor of 2 peripheral  central N. Grau Columbia University 10/17/05

  21. Trigger 5-10 GeV/c More on Associated Yields • Associated yields multiplied by a factor to put them on the same scale • Suppression stronger at lower pT • Consistent with flat to a factor of two suppression at highest pT J. Jin QM2005 poster N. Grau Columbia University 10/17/05

  22. Picture of High-pT Jets Very different centrality dependence of these observables. Are these results reconcilable in E-loss picture? What are the implications for jet tomography? N. Grau Columbia University 10/17/05

  23. Non-Gaussian Away-side Shape at Lower pT N. Grau Columbia University 10/17/05

  24. Extracting Jet Correlations in A+A (I) • Assumptions: • Two source model • Elliptic flow • Di-jets • v2 from reaction plane measurements • <v2trigv2assoc> = <v2trig><v2assoc> • Similar assumptions between PHENIX and STAR N. Grau Columbia University 10/17/05

  25. Extracting Jet Correlations in A+A (II) • Extraction of the background level • Absolute normalization • Parameter in the fit of C(Df) • Assume Zero Yield from jets At the Minimum of the C(Df) (ZYAM) • Similar to STAR from disappearance paper. • Typically 1-2% difference between results • but jet S/B few % at low and intermediate pT • Large yield uncertainties, less effect on the shape N. Grau Columbia University 10/17/05

  26. Au+Au Correlations from High to Low pT J. Jia QM2005 Poster ZYAM subtracted, green/blue lines indicate subtraction uncertainty. h-h Most peripheral collisions: Jet is seen for all pT Onset of away-side jet modification in semi-peripheral collisions. Flattening and dip structure at low pT and at high centrality. N. Grau Columbia University 10/17/05

  27. Formation of a Local Minimum J. Jia QM2005 Poster h-h PHENIX preliminary Flat correlation where a harmonic is present. C(Df) strength ~ S/B. N. Grau Columbia University 10/17/05

  28. csQGP= Evidence of Mach Cones STAR Preliminary =+/-1.23=1.91,4.37 J. Casalderrey-Solana, E. ShuryakandD. Teaney hep-ph/0411315 N. Grau Columbia University 10/17/05

  29. Or Cerenkov Radiation Koch, Majumder, Wang nucl-th/0507063 Requires colored bound states (mass m) in medium (temperature T). Strong p-dependence of cone angle N. Grau Columbia University 10/17/05

  30. assoc D trigg D assoc Testing the Splitting Parameterize the away-side shape as a double Gaussian that are offset symmetrically around Df = p by fit parameter D. Could be a “bent” jet or a mach/ Cherenkov cone – no physics assumption made N. Grau Columbia University 10/17/05

  31. Parameterize the Away-Side Shape P. Constantin QM2005 Poster • Smooth increase splitting with centrality • Plateau at most central • Lowest pT correlations systematically above the higher pT correlations. • Possible indication of Cerenkov-like radiation? PHENIX Preliminary N. Grau Columbia University 10/17/05

  32. System Size and Energy Systematics of Away-Side Shape Au+Au @ 62.4 GeV h-h 2.5-4 x 1-2.5 GeV/c PHENIX Preliminary J. Frantz QM2005 poster D is independent of system and energy. Is this reconcilable with Mach or Cerenkov cones? N. Grau Columbia University 10/17/05

  33. Dip Persists at SPS M. Ploskon QM2005 Poster • CERES data at much lower root-s but similar trigger and associated pT ranges • higher xT – quark jet dominated • Background by ZYAM • Correlation is flat at far angles – dip present at SPS at a smaller level! N. Grau Columbia University 10/17/05

  34. Near Side Broadening PHENIX Preliminary A. Kravitz QM2005 Poster Systematic trend of broadening as a function of centrality. First observation of medium effect on the near side. N. Grau Columbia University 10/17/05

  35. Other New/Upcoming/Interesting Jet Correlations N. Grau Columbia University 10/17/05

  36. PHENIX Preliminary Mach cone Simulation Flow+Jet Three-particle Correlations: Mach/Cerenkov Cone • Trigger 2.5-4 GeV/c • Two associated particles 1-2.5 GeV/c • Choose specific reaction plane bin such that v2trig = 0 • Contains correlations between the associated particles N. Grau Columbia University 10/17/05

  37. Reaction Plane Dependence: Path Length Dependence Red– 6Green – 5Blue – 4Light Blue – 2Pink – 1 Black - Integral J. Jia QM2005 Poster Require the trigger particle within a given RP orientation Flow varies in a particular way J. Bielcikova et al Phys. Rev. C69:021901, 2004 N. Grau Columbia University 10/17/05

  38. Electron Triggered Correlations:Heavy Quark Energy Loss 1-4 GeV/c F. Matathias QM2005 Poster Use jet correlations to further understand heavy quark energy loss. N. Grau Columbia University 10/17/05

  39. g Hadrons Direct-g Triggered Correlations: Holy Grail of Energy Loss Studies PRL 94 232301 (2005) Direct photons not suppressed in the medium. N. Grau Columbia University 10/17/05

  40. C(Df) C(Df) Df Df Inclusive g-h Correlations in Au+Au J. Jin QM2005 Poster g: 5-10 GeV/c h: 1-2 GeV/c g: 5-10 GeV/c h: 3-5 GeV/c Comparison with p0 triggered data necessary to extract direct photon correlations. N. Grau Columbia University 10/17/05

  41. Conclusions • d+Au jets look like p+p jets. • Multiple scattering small • Jets at high pT in Au+Au collisions • Show no away-side width broadening • Show suppression of away-side yields • Jets at low pT Au+Au: strong shape modifications • Due to a medium? Effect at lower root-s and different systems. • What properties can we extract? cs, n, etc. • More results to come • Three-particle correlations, reaction plane dependence, heavy flavor tagging • Prompt-g-jet correlations! N. Grau Columbia University 10/17/05

  42. Backup Slides N. Grau Columbia University 10/17/05

  43. PRL 91, 072303 (2003) Cronin Effect in Single Inclusive Particle Production in d+Au PRL 91, 072304 (2003) • Enhancement at mid-pT • Meson-Baryon difference • Look for jet acoplanarity in d+Au vs p+p N. Grau Columbia University 10/17/05

  44. Open: p+p, Closed: d+Au Triggers p0p+/- Jet Acoplanarity in p+p and d+Au Independent Fragmentation Model: N. Grau Columbia University 10/17/05

  45. Fragmentation Functions Scaled z at high trigger pT. N. Grau Columbia University 10/17/05

  46. d+Au p+p dN/dxE Scaling PHENIX Preliminary PHENIX Preliminary p+p and d+Au are similar N. Grau Columbia University 10/17/05

  47. a L1 L2 L1 c L2 b L1 L2 Unchanging Jet Widths: Possible Implications A. Dainese et al, EJPC 38 (2005) 461 • Away-side jet fragments in vacuum and parent parton unaffected by medium? • Tangential jets? • Suppressed production area/volume of the colliding region • Inconsistent with inclusive RAA • Punch throughs • Little E-loss/multiple scattering N. Grau Columbia University 10/17/05

  48. Lack of Near Side Broadening at High pT At higher pT, no increase with centrality Consistent with the picture of production at the corona. N. Grau Columbia University 10/17/05

  49. Reaction Plane Dependence at Higher pT High trigger pT High associated pT N. Grau Columbia University 10/17/05

  50. RP Dependence of Near Angle Widths Near angle widths are flat as a function of reaction plane – still consistent with production at the corona N. Grau Columbia University 10/17/05

More Related