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Azimuthal and HBT Correlations of Particles with Strangeness

Azimuthal and HBT Correlations of Particles with Strangeness. Roy A. Lacey USB - Chem (SUNY Stony Brook). Outline. HBT Motivation Selected Results/Implications Azimuthal Correlations Motivation Info in Correlations Selected Results/Implications Summary. NOTE !!

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Azimuthal and HBT Correlations of Particles with Strangeness

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  1. Azimuthal and HBT Correlations of Particles with Strangeness Roy A. Lacey USB - Chem (SUNY Stony Brook)

  2. Outline • HBT • Motivation • Selected Results/Implications • Azimuthal Correlations • Motivation • Info in Correlations • Selected Results/Implications • Summary NOTE !! Strange Particle Azimuthal and HBT Correlation Measurements are NOT Pervasive. Roy A. Lacey

  3. HBT allows quantification of contributions to space-time evolution (STE) of system reactionplane • Lifetime and duration of emission • Spatial extent of system • Collective flow at thermal freeze-out • HBT() provides direct access to shape and orientation of source • Predicted Signatures for QGP fp=90° Rside (small) Rside (large) fP=0° Observables 3 radii: Time duration : chaoticity: Why Study HBT Correlations Probability to detect 2 particles at p1 and p2, (pair relative momentum) In the Longitudinal CMS, where (p1+p2)beam = 0, Roy A. Lacey

  4. What is the Value of Strange Particle Azimuthal and HBT Correlations ? Roy A. Lacey

  5. 4fm 6fm 10fm -p correlations are more sensitive than p-p for large sources Value of Strange Particle HBT Correlations Accurate Source Size Determination F.Wang & S. Pratt PRL 83, 3138, 1999 Roy A. Lacey

  6. Strange Particles aid Access to Possible Space-time Asymmetries Value of Strange Particle HBT Correlations Access to Space-time Asymmetries Catching up  Large interaction time  Large correlation p Moving away  Small interaction time  Small correlation p • Ratio or Difference • Sensitive to the space-time asymmetry C. Gelderloos et al NIM A349, 618 (1994) R. Lednicky et al PLB 373, 30 (1996) Roy A. Lacey

  7.  Fraction of particles Results Chung et al (E895) Imaging Technique Brown Danielewicz PRC 64, 14902 (2001) Kernel Encodes ( FSI) Source Function: Prob. of emitting a pair of particles with separation r in pair c.m.  (short and long range) High Quality Source Functions Allow Detailed Comparisons Between pp, pi-pi, and /\p Roy A. Lacey

  8. The Naive Expectation of is not Followed Results/Implications Chung et al (E895) • Half of the pions come from • A source with • (1/2 from larger source) • ~ 51% of protons come • from a compact source • ~ 60% of p/\ pairs come • from intermediate size • source. • -- emission time diff.? • -- difference in flow ? Estimates for /\ source Roy A. Lacey

  9. Insensitive to pT over Range of Measurements. Substantial change in fraction of particles which contribute to short-range source Results Roy A. Lacey

  10. Results /\p • Fit with theoretical CF • (effective range approx) • R. Lednicky • Sov. J. Nucl. Phys. 35, 770 (1982) • S-wave scattering length • f0=-2.3/-1.8 • (singlet/triplet) Preliminary NA49 Data Indicate Similar Radius value Roy A. Lacey

  11. Correlations Results • Fit with theoretical CF • S-wave scattering length Suggestive of Small Scattering Lengths nn s-wave ~ 20 fm Roy A. Lacey

  12. Correlations Results Uncorrected Large Radius ? Mt Scaling ? Roy A. Lacey

  13. Value of Strange Particle HBT Correlations Access to Space-time Asymmetries Catching up  Large interaction time  Large correlation p Moving away  Small interaction time  Small correlation p • Ratio or Difference • Sensitive to the space-time asymmetry C. Gelderloos et al NIM A349, 618 (1994) R. Lednicky et al PLB 373, 30 (1996) Roy A. Lacey

  14. Results • Fit in pair rest frame • <r*pion-r*kaon> • = -6.8 fm • Dr* = g (Dr - bDt) • tpion-tkaon < 6.4 fm/c • rkaon-rpion < 4.6 fm Data Suggest Important Space-time Asymmetry in Emission Pattern for different Particles Roy A. Lacey

  15. CGC: • Provides insights on Saturation Physics Why Azimuthal Correlations • Jets: • Primarily from gluons at RHIC • Sensitive to the QCD medium (dE/dx) • Flow: • Primarily from pressure build-up • Reflect conditions in collision zone (EOS) Correlation Studies can provide information on the particle production mechanism,the EOS, Initial State effects QGP formation…. (Very Important Signal) Roy A. Lacey

  16. Extracting Azimuthal Correlations There are Several Methods Currently being Exploited to Extract the Anisotropy and Asymmetry of Correlations • Reaction Plane method • Correlation Function Method: 1.) correlate particles (1 and 2) from the same pT range (fixed pT) 2.) Correlate particle 1 in a given pT bin with particles of arbitrary or Fixed pT(Assorted pT) • Multiparticle correlations: Three-Particle Correlations, Cumulants Roy A. Lacey

  17. Asymmetry ( ) Anisotropy ( ) Establishing Definitions Azimuthal Distributions and Correlation Functions are Characterized by an Anisotropy and an Asymmetry. Roy A. Lacey

  18. Saturation Model Mini-Jets, lead to strong anisotropy and an asymmetry Information in Correlation Functions HIJING Hydro or Transport With large Opacity Flow leads to strong anisotropy Jets lead to strong anisotropy and an asymmetry The anisotropy of the correlation function can reflect both flow-like and Jet contributions – Detailed Differential Studies Required !! Roy A. Lacey

  19. What Kind of Insights Do Strange Particles Provide ? E895 Clear Evidence for in-medium potential at AGS Energies Roy A. Lacey

  20. Star Flavor Composition of v2 is Crucial Differential Measurements Roy A. Lacey

  21. Anisotropy Pattern is Species Dependent Roy A. Lacey

  22. Differential Measurements PHENIX STAR Good Agreement Between Experiments Preliminary Flavor Composition of v2 is Crucial Roy A. Lacey

  23. Differential Correlation Functions • Asymmetry of Correlation • function sensitive to: • pT Reference • Selection • Charge Selection • Consistent with presence of • Jets/Minijets • Extracted v2 relatively • insensitive Illustrative Sketch Illustrative Sketch • Asymmetry Sensitive to pTRef Roy A. Lacey

  24. v2 Scaling Scaling observed in models Molnar et al. Goal: Apply scaling to p+p & d+A and compare to A+A Roy A. Lacey

  25. Summary Correlation Measurements serve as an important probe for the high-energy-density nuclear matter . Measurements Involving Strange Particles Provide: • A Wealth of Insights on Reaction Dynamics • Several Examples Given (HBT, Azimuthal Correlations) • Better Understanding of Probes Crucial to the Search for the QGP Much Much More to Come !! Roy A. Lacey

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