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Femtoscopic and long-range correlations in p+p and Au+Au collisions

Midwest Critical Mass Toledo, Ohio , 21 - 22 October , 2005. Femtoscopic and long-range correlations in p+p and Au+Au collisions. Zbigniew Chaj ę cki The Ohio State University for the STAR Collaboration. Outline. Dynamics of the collisions

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Femtoscopic and long-range correlations in p+p and Au+Au collisions

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  1. Midwest Critical MassToledo, Ohio, 21-22 October, 2005 Femtoscopic and long-range correlations in p+p and Au+Au collisions Zbigniew Chajęcki The Ohio State Universityfor the STAR Collaboration

  2. Outline • Dynamics of the collisions • mT dependence of HBT radii in p+p, d(p)+Au, Au+Au • p+p → Au+Au : New (changing) physics? • Non-femtoscopic correlations • problem with baseline of CF in low multiplicity collisions • shape analysis of correlation function • phase-space distortion MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  3. Transverse mass dependence in Au+Au STAR, Au+Au@200GeV, PRC71 (2005) 044906 0. 0. 0. .2 0.2 0.3 0.4 0.5 0.2 0.3 0.4 0.5 0.6 In Au+Au pT (mT) dependence attributed to collective expansion of the source Calc. with Blast-Wave -Retiere, Lisa,PRC 70 (2004) 044907 MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  4. Transverse mass dependence in Au+Au Au+Au 62GeV – STAR preliminary bx=0.907 bx=0.974 p K p MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  5. Transverse mass dependence: p+p, d(p)+Au STAR preliminary mT dependencein elementary collisions (e.g. OPAL, DELPHI, E735) usually attributed to • String fragmentation • Resonance contribution • Heisenberg uncertainty DELPHI - e+e- annihilation DELPHI - e+e- annihilation DELPHI - e+e- annihilation G. Alexander, hep-ph/0302130 • p+p: HBT radii decrease with increase of mT MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  6. p+p like a little Au+Au ? flow not expected in such a small system as p+p see e.g. Shuryak:hep-ph/0405066 • Csorgoet al.: mT dependence of HBT radii in pp is not generated by the transverse flow, but by the transverse temperature inhomegeneities of hadron-hadron collisions due to the freezing scale –hep-ph/0406042 1/(2pmT)d2n/(dmTdy) mT-m (GeV) • d+Au : Rlong doesn’t change with centrality RSIDE ROUT RLONG MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  7. Surprising scaling Ratio of (AuAu, CuCu, dAu) HBT radii by pp pp, dAu, CuCu - STAR preliminary • All pT(mT) dependences of HBT radii observed bySTAR scale with pp although it’s expected that different origins drivethese dependences HBT radii scale with pp Scary coincidence or something deeper? MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  8. Let's look in more detail at where these radii come from MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  9. Decomposition of CF onto Spherical Harmonics d+Au: peripheral collisions d+Au: peripheral collisions Au+Au: central collisions RL < RT ~acceptance free RL > RT RO < RS Simple, Gaussian source calculations QLONG Q RO > RS  QOUT  QSIDE Au+Au: central collisions C(Qout) C(Qside) C(Qlong) Z.Ch., Gutierrez, Lisa, Lopez-Noriega, nucl-ex/0505009 Pratt, Danielewicz [nucl-th/0501003] STAR preliminary MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  10. Including Al=2,m in a fit d+Au: peripheral collisions b |Q| |Q| z |Q| MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  11. Scaling (fit w/ baseline param.) Ratio of (AuAu, CuCu, dAu) HBT radii by pp STAR preliminary NEW fit w/ baseline parameterization Fit w/o baseline parameterization MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  12. NA22 parametrization of CF ”ad hoc” term MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  13. NA22: 1D projections of 3D CF NA22, Z. Phys. C71 (1996) 405 MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  14. NA22 fit to STAR data STAR preliminary d+Au peripheral collisions NA22 fit d+Au peripheral collisions MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  15. p-lambda correlations at CLAS, A. Stavinsky, WPCF 2005 MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  16. Phase-Space Distortion with GenBod • Generator needs the following information: • Multiplicity • Mass of each particle • Energy of the collision • Cross-section (constant or Fermi energy-dependent) • Generator returns: • Momentum of each particle, mass and energy • Weight for each event that is proportional to the phase space integral Energy and momentum is conserved ! MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  17. SHD of CF generated with GenBod d+Au: peripheral collisions b |Q| |Q| z |Q| arbitrary MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  18. Summary • mT dependence of HBT radii for Au+Au, Cu+Cu, d+Au and p+p seems to be the same although it’s expected to have different origins • Decomposition of CF in terms of spherical harmonics • Spherical harmonics allow efficent diagnostic of the correlation function • Use symmetry of the Q-space • Pratt and Danielewicz [nucl-th/0501003]: connection of one-to-oneCF and spatial anisotropies • Hope to parametrize non-femtoscopic correlations (phase-space distortion) MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  19. . SUPPORT SLIDES MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  20. Transverse mass dependence: p+p, d(p)+Au Note y-scale change! STAR preliminary • p+p: HBT radii decrease with increase of mT • d+Au collisions • centrality dependence observed • Rside sensitive to the size of a smaller nucleus (d+Au vs p+Au) MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  21. „Universal” scaling ? RHIC/AGS/SPS Systematics Pion HBT radii from different systems and at different energies scale with (dNch/dη)1/3 <kT>≈ 400 MeV (RHIC)<kT>≈ 390 MeV (SPS) STAR DATA (pp,dAu,CuCu,AuAu@62GeV - prelim.) Radii scale with multiplicity Forget A,B,√s, Npart...dN/d determines HBT radii,at all mT(!!!!) Lisa, Pratt, Soltz, Wiedemann, nucl-ex/0505014 MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  22. System expansion: Initial vs Final Size Collisions at 200GeV only Smooth (but not trivial) expansion of the system from p+p to Au+Au AuAu: system expands pp (dAu): no or less expansion Proton initial size = 0.89 fm from e-scattering MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  23. Decomposition of CF onto spherical harmonics QLONG Q  QOUT  QSIDE Z.Ch., Gutierrez, Lisa, Lopez-Noriega, nucl-ex/0505009 • Cartesian-space (out-side-long) naturally encodes physics, but is poor/inefficient representation • Recognize symmetries of Q-space -- decompose by spherical harmonics! • Direct connection to source shapes [Danielewicz,Pratt: nucl-th/0501003] – decomposition of CF on cartesian harmonics • ~immune to acceptance • full information content at a glance[thanks to symmetries]  : [0,2p]  : [0,p] MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  24. Some properties of Alm coefficients • Alm = 0 for l or m odd – identical particle correlations (for non-id particles, odd l encodes shift information) • A00(Q) ≈ one-dimensional “CF(Qinv)”(bump ~ 1/R) • Alm(Q) = l,0 where correlations vanish • Al≠0,m(Q) ≠ 0  anisotropy in Q space • Im[Alm] = 0 MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

  25. Baseline in p+p, d+Au and Au+Au • Some coefficients don’t vanish for large Q • Bias from zero is larger for more peripheral collisions • This problem is getting more significant for small systems (pp & dAu) • It can be due to • an experimental artifact • long range correlations (e.g. Jets) • problem with momentum conservation ? • or ? MCM 2005 - Zbigniew Chajęcki for the STAR Collaboration

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