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Femtoscopy in STAR vs world systematics

Femtoscopy in STAR vs world systematics. Zbigniew Chaj ę cki, OSU for the Collaboration. Outline. HBT in Heavy-Ion Collisions at RHIC Multiplicity as universal scaling R(m T ) - direct probe of flow scenario Femtoscopy in p+p [reminder]

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Femtoscopy in STAR vs world systematics

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  1. Femtoscopy in STAR vs world systematics Zbigniew Chajęcki, OSUfor the Collaboration Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  2. Outline • HBT in Heavy-Ion Collisions at RHIC • Multiplicity as universal scaling • R(mT) - direct probe of flow scenario • Femtoscopy in p+p [reminder] • mT scaling of HBT radii (AA/pp) [reminder] • Energy and Momentum Conservation Induced Correlations in p+p • STAR results from p+p (all fits) • world systematics : Rinv(N,mT), Ro,s,l(mT) • How different is pp from AA at the end? Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  3. Heavy ions at RHIC Multidimensional analysis at RHICR(√SNN, mT, b, Npart, A, B, PID) ... but is there a scaling variable? Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  4. Multiplicity scaling of HBT radii at RHIC Radii scale with multiplicity Lisa, Pratt, Soltz, Wiedemann, Ann.Rev.Nucl.Part.Sci. 55 (2005) 357-402 Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  5. mT dependence of pion HBT radii • Flow is the most important bulk feature at RHIC • mT-dependence of femtoscopy probes flow the most directly • quantitative agreement w/p-only observables Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  6. Femtoscopy - direct evidence of flow Spectra v2 R (fm) space-momentum substructure mapped in detail STAR PRL 91 262301 (2003) HBT mT (GeV/c)  K Flow-dominated “Blast-wave” toy models capture main characteristics e.g. PRC70 044907 (2004) Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009 6

  7. Id-pion correlations in p+p STAR preliminary mT [GeV/c2] mT [GeV/c2] • p+p and A+A measured in thesame experiment • great opportunity to compare physics • what causes pT-dependence in p+p? • same cause as in A+A? Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  8. Femtoscopy in pp vs heavy ions Ratio of (AuAu, CuCu, dAu) HBT radii by pp HBT radii scale with pp Scary coincidence or something deeper? pp, dAu, CuCu - STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  9. Non-femto correlations / SH representation d+Au: peripheral collisions STAR preliminary Z.Ch., Gutierrez, Lisa, Lopez-Noriega, [nucl-ex/0505009] Pratt, Danielewicz [nucl-th/0501003] STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  10. Decomposition of CF onto Spherical Harmonics Au+Au: central collisions C(Qout) C(Qside) C(Qlong) Z.Ch., Gutierrez, Lisa, Lopez-Noriega, [nucl-ex/0505009] Pratt, Danielewicz [nucl-th/0501003] Qx<0.03 GeV/c Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  11. Non-femtoscopic correlations in STAR N-dep. of non-femtoscopic correlations in p+p STAR preliminary Baseline problem is increasing with decreasing multiplicity STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  12. EMCICs in other experiments Multiplicity increases Qx<0.2 GeV/c E766, PRD 49 (1994) 4373 OPAL, Eur. Phys. J. C52 (2007) 787-803 Qx<0.04 GeV/c NA23, Z. Phys. C43 (1989) 341 CLEO PRD32 (1985) 2294 NA22, Z. Phys. C71 (1996) 405 Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  13. Common approaches to „remove” non-femtoscopic correlations b |Q| |Q| z |Q| • MC simulations • ‘ad-hoc’ parameterizations • OPAL, NA22, … • “zeta-beta” fit by STAR [parameterization of non-femtoscopic correlations in Alm’s] • An alternative explanation:Energy and Momentum Conservation Induced Correlations, Z.Ch. and Mike Lisa [PRC 78 (2008) 064903, ArXiv:0803.022] Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  14. k-particle distributions w/ phase-space constraints k-particle distribution (k<N) with P.S. restriction single-particle distribution w/o P.S. restriction observed P - total 4-momentum Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  15. k-particle distribution N.B. relevant later k-particle distribution in N-particle system • Danielewicz et al, PRC38 120 (1988) • Borghini, Dinh, & Ollitraut PRC62 034902 (2000) • Borghini Eur. Phys. J. C30:381-385, (2003) • Chajecki & Lisa, PRC78 (2008) 064903 arXiv:0803.0022 * “large”: N > ~10 Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  16. The Complete Experimentalist’s Recipe 9 fit parameters - 4 femtoscopic - normalization - 4 EMCICs or any other parameterization of CF Fit this …. Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  17. EMCIC fit to STAR p+p data kT = [0.15,0.25] GeV/c kT = [0.25,0.35] GeV/c kT = [0.35,0.45] GeV/c kT = [0.45,0.60] GeV/c STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  18. Fit results: EMCIC parameters Five physical variables - four fit parameters Can we verify whether kinematic variables showing up in fit parameters have physical values? STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  19. Various fits to STAR p+p data STAR preliminary STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  20. mT scaling of HBT radii STAR preliminary Various fits give different radii but mT scaling of HBT radii still holds Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  21. Multiplicity dependence in p+p STAR preliminary 200 GeV Rinv [fm] Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  22. p+p vs heavy ions - R(N,mT) STAR preliminary Similar mT and multiplicity dependence of HBT radii in p+p and heavy ions in STAR Is STAR p+p unique? Let’s look at world’s results on HBT in elementary particle collisions … Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  23. Femtoscopy in small systems R ≈ 0.5 - 1.5 fm Z.Ch. arXiv:0901.4078 [nucl-ex] Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  24. My first impression Can we do a direct comparison between experiments? Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  25. Parameterizations of 1D CF used in comparision b/w experiments RB≈2·RG Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  26. R(N) - world systematics STAR preliminary • R(N,<mT>) • no point to compare the magnitude of the HBT radii between experiments since almost each experiment has different <pT>; e.g. <pT>(E735) > <pT>(STAR) • look for trends, instead! Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  27. 1D R(pT) STAR preliminary * ** Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  28. 3D R(mT) STAR preliminary Leptonic results included! Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  29. EMCICs seen in small systems Femtoscopy similar in p+p as in Au+Au @ STAR “World results” show both pT and N dependence! Same physics in p+p as in Au+Au and the only difference due to phase-space effects? possibilities: HBT signals are insensitive to underlying physics (flow etc) they are sensitive & the very different physics of A+A and p+p look coincidentally identical they are sensitive, and driving physics is the same Summary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  30. Rinv(N,√s) - world systematics 7.21 GeV 21.7 GeV 27.4 GeV 31-62 GeV 200 GeV 1800 GeV STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

  31. RG/RB(N, √s) - world systematics UA1 21.7 GeV 53-126 GeV 200-900 GeV 200 GeV 1800 GeV STAR preliminary Z. Ch. for STAR - WWND 2009, Big Sky, MT, Feb. 1-8, 2009

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