mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic1 Recent developments in femtoscopy at RHIC* Mike Lisa Ohio State University * not an overview talk

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic2 Outline Motivation & Reminders: space-time, H.I.C., pion correlations Status of present program: exploiting huge systematics Selected results femtoscopy of identical and non-identical particles Harmonic decomposition - isolating geometrical effects comparison with p+p collisions (in same detector!) Harmonic decomposition - isolating non-femtoscopic correlations Summary

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic3 “”“” Rischke, Gyulassy, NP A 608 (1996) 479 R out /R side R(√S NN, b, N part, A, B, m T, y, , PID) R(√S NN ) – simple signal ? No glaring signal in simple measures The „real” (experimentalist’s) „puzzle” mass |b| pTpT

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic4 Wide range of RHIC

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic5 Vary colliding system does physics change? requires dedicated program Vary kinematic variables space-time dynamics requires large acceptance Vary particle type consistent picture? unique probe of dynamical structure requires good particle identification & acceptance R(√S NN, b, N part, A, B, m T, y, , PID)

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic6 Possibilities in a dedicated program: 5 Also: 62.4 & 200 GeV Gunther Roland, QM05

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic7 R(√S NN, b, N part, A, B, m T, y, , PID) MAL, Pratt, Soltz, Wiedemann nucl-ex/

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic8 R(√S NN, b, N part, A, B, y, m T, , PID) Lisa, Pratt, Soltz, Wiedemann, nucl-ex/ Z. Chajecki, QM05

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic9 R(√S NN, b, N part, A, B, y, m T, , PID) Lisa, Pratt, Soltz, Wiedemann, nucl-ex/ Z. Chajecki, QM05 MAL, Pratt, Soltz, Wiedemann nucl-ex/ STAR, PRL 2004

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic10 H.D. and application to CF for identical & non-identical particles

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic11 Usual 1D out-side-long “Cartesian projections” limited view of data ~set of zero measure of 3D CF Fit-violating trends may be hidden Salient geometrical effects non-trivially convoluted acceptance-dependent (unlike 3D CF) 1D projections: a limited view “Gaussian fit” (remember: not Gaussian CF) out sidelong STAR PRC (2005) Harmonic Decomposition Analysis exploits full symmetry of q-space explicit isolation of femtoscopic (& non-femtoscopic) effects full 3D CF seen clearly in few plots acceptance-robust (*) nucl-th/ Cartesian HD Danielewicz & Pratt nucl-th/ nucl-ex/ Spherical HD Chajecki,Gutierrez,MAL,Lopez nucl-ex/ Michael Lisa: “Salient geometrical...” bullet just means: if I want to know “Rlong” or so, I *mostly* just look at width of long projection, but there are also acceptance effects Michael Lisa: “Salient geometrical...” bullet just means: if I want to know “Rlong” or so, I *mostly* just look at width of long projection, but there are also acceptance effects

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic12 Spherical harmonic decomposition of CF Q OUT   Q SIDE Q LONG Q Cartesian-space (out-side-long) naturally encodes physics, but is “inefficient” representation Harmonic Moments -- 1::1 connection to source geometry [Danielewicz,Pratt: nucl-th/ ] ~immune to acceptance full information content at a glance [thanks to symmetries] Chajecki., Gutierrez, MAL, Lopez-Noriega, nucl-ex/

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic13 STAR preliminary A00A00 A20A20 A22A22 SH Moments STAR Central Au+Au collisions -- Spherical HD C(Q out ) C(Q side ) C(Q long ) 1D o-s-l projections Chajecki., Gutierrez, MAL Lopez-Noriega, nucl-ex/

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic14 “Mental calibration” - a Gaussian CF Simple, Gaussian source calculations ~acceptance free R L < R T R L > R T R O < R S R O > R S Full 3D structure (high-L (fine structure) coefficients drop off) Different geometrical aspects separate & use “all” relevant information in the CF A L≠0 vanishes in non-femtoscopic region

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic15 KooninPratt Danielewicz and Pratt nucl-th/ P. Chung, QM05 Alternative: Cartesian Harmonic Decomposition Correlation function Source function

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic16 PHENIX Preliminary P. Chung, QM05 CHD:  from central Au+Au collisions L = 1 out side long L = 0 L = 2 out side long L = 4 out side long “Size” C 0 (q inv )  C 1D (q inv ) Source deformation manifest “R long ” > “R out ” > “R side ” higher-order structure symmetry: odd L vanish here But, interesting for non-id

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic17 RHIC femtoscopy with wide variety of particle species ++ -- K+K+ K-K- K0SK0S p pp  ++ --  -  K+K+  K-K-  --K0SK0S  p pp     ! R(√S NN, b, N part, A, B, m T, y, , PID 1, PID 2 )  = prelim or final result available

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic18  ± -  ± correlations in 200 GeV Au+Au like-sign vs unlike-signcentral vs peripheral ++ & -- consistent Coulomb-dominated +- & -+ consistent Coulomb + strong Expected centrality dependence “  *” sensitive Wonderful...but there’s more!... P. Chaloupka, QM05

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic19 Geometric effects of collective flow ● Correlation between momentum and emission point ● reduces source size shifts average emission point ● Effect increases with m T Pion pt = 0.15 GeV/c Proton pt = 1. GeV/c Ξ - pt = 1.4 GeV/c Ω - pt = 1.8 GeV/c Emission points from Blast-wave βt = 0.73 for all species Non-identical particle correlations uniquely probe dynamic structure R. Lednicky, nucl-th/ Retiere & MAL, PRC

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic20 SHD of non-identical particle correlations A 00 - monopole  size A 11 - dipole  shift A 2m - quadrupole  shape.....

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic21 Accessing asymmetry A 11 ≠ 0 in correlation regions  Asymmetry in the average emission point between p-X In the “right” direction (cf BW) details: P. WPCF

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic22 Another first -- femtoscopy in p+p collisions in same detector (same systematics) as in A+A

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic23 femtoscopy in STAR DELPHI Z 0 LEP m, m T (GeV) R (fm) R Z (fm) hep-ph/   K p  STAR preliminary m T (GeV) 1. Heisenberg uncertainty? e.g. G. Alexander “plausible” in z-direction unlikely in transvrse 2. String fragmentation? (Lund) p T dependence maybe (??) mass dependence probably no [Andersson, Moriond 2000] 3. Resonance effects? e.g. Wiedemann & Heinz ‘97 maybe, but presumably significantly different effect than for Au+Au under investigation Zbigniew Chajecki QM05 p+p and A+A measured in same experiment great opportunity to compare physics what causes pT-dependence in p+p? same cause as in A+A?

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic24 femtoscopy in STAR DELPHI Z 0 LEP m, m T (GeV) R (fm) R Z (fm) hep-ph/   K p  STAR preliminary m T (GeV) 1. Heisenberg uncertainty? 2. String fragmentation? (Lund) 3. Resonance effects? Zbigniew Chajecki QM05 p+p and A+A measured in same experiment great opportunity to compare physics what causes pT-dependence in p+p? same cause as in A+A?  d+Au : Rlong doesn’t change with centrality flow not expected in such a small system as p+p e.g. Shuryak: hep-ph/  Csorgo et al.: Buda-Lund treatment of p+p collision as bulk system (w/ temperature gradients) hep-ph/ R OUT R SIDE R LONG m T -m (GeV) 1/(2  m T )d 2 n/(dm T dy)  K p m T (GeV) 4. Bulk system („hydro”) in pp?

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic25 Surprising („puzzling”) scaling  All p T (m T ) dependences of HBT radii observed by STAR scale with pp although it’s expected that different origins drive these dependences HBT radii scale with pp Scary coincidence or something deeper? pp, dAu, CuCu - STAR preliminary Ratio of (AuAu, CuCu, dAu) HBT radii by pp

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic26 Baseline problems with smallest systems STAR preliminary d+Au peripheral collisions Gaussian fit ad hoc, but try it...

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic27 STAR preliminary d+Au peripheral collisions NA22 fit Try NA22 empirical form NA22 fit data Spherical harmonics L =1 M=0 L =2 M=0 L =1 M=1 L =2 M=2

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic28 “account for” constant offset in L=2 components STAR preliminary d+Au peripheral collisions Gaussian fit |Q|   A02A02 A22A22 A00A00 Gaussian + constant A 0 2, A 2 2

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic29 With L=2 shifts, message remains Ratio of (AuAu, CuCu, dAu) HBT radii by pp Fit w/o baseline parameterization NEW fit w/ baseline parameterization STAR preliminary To be continued...

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic30 Summary Very active, systematic femtoscopic program at RHIC A few new results detailed shape studies: (for many particle types) exotic correlations: substructure of space-time dynamics of  experimental comparison of femtoscopy in hadronic/nuclear collisions New methods Harmonic analysis : much to offer New questions dynamic substructure picture “confirmed”... eliminate theories/models? similarity of p+p & Au+Au (& d+Au) : “deep” or coincidental? A healthy, important (sub)field ! R(√S NN, b, N part, A, B, m T, y, , PID 1, PID 2 )

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic31 Conclusion/summary COMPLETE experimental program: huge multidimensional systematic effort at dedicated facility with large acceptance new method [important to exploit the new data] fully exploits q-space symmetries: efficient representation of full 3D correlation function [my opinion: this is the end of Cartesian projections] different physics aspects separated cleanly (l=0,1,2...) excellent diagnostic for identifying/characterizing nonfemtoscopic correlation effects (& including them in fit) new data extend PID beyond pions for sizes: consistency of scenario non-id for shifts: new information also (qualitatively) consistent vary system [A,B,√s, Npart] (CuCu,AuAu,dAu,200,64GeV) multiplicity scaling “elementary” systems “3rd HBT puzzle” Insert closing comment / “big picture conclusion” here

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic32 Extra slides

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic33 Geometric effects of collective flow ● Correlation between momentum and emission point ● reduces source size shifts average emission point ● Effect increases with m T Pion pt = 0.15 GeV/c Proton pt = 1. GeV/c Ξ - pt = 1.4 GeV/c Ω - pt = 1.8 GeV/c Emission points from Blast-wave βt = 0.73 for all species Non-identical particle correlations uniquely probe dynamic structure R. Lednicky, nucl-th/ Petr Chaloupka QM05 Retiere & MAL, PRC Comment : Cramer/Miller: 12 parameters to reproduce one particletype BW+stat: 5+2 parameters to reproduce “all” particletypes

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic34 Spacetime - an annoying detail in H.I.C. ? Non-trivial space-time - the hallmark of rhic Initial state: dominates further dynamics Intermediate state: impt element in exciting signals Final state: Geometric structural scale is THE defining feature of QGP STAR, PRC66 (2002) STAR, PRL93 (2004)

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic35 q out q side q long Hanbury Brown-Twiss interferometry R side R long R out x1x1 x2x2 p1p1 p2p2 Two-particle interferometry: p-space separation  space-time separation HBT: Quantum interference between identical particles q (GeV/c) C (q) 1 2 Final-state effects (Coulomb, strong) also can cause correlations, need to be accounted for Gaussian model (3-d):

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic36 q out q side q long Hanbury Brown-Twiss interferometry R side R long R out x1x1 x2x2 p1p1 p2p2 Two-particle interferometry: p-space separation  space-time separation R side R out

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic37 Spacetime - an annoying detail in H.I.C. ? Non-trivial space-time - the hallmark of rhic Initial state: dominates further dynamics Intermediate state: impt element in exciting signals Final state: Geometric structural scale is THE defining feature of QGP Temporal scale sensitive to deconfinement transition (?) Ann.Rev.Nucl.Part.Sci. 46 (1996) 71

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic38 C(Q out ) C(Q side ) C(Q long ) STAR preliminary A00A00 A20A20 A22A22 SH Moments STAR Central Au+Au collisions -- Spherical HD 1D o-s-l projections Chajecki., Gutierrez, MAL Lopez-Noriega, nucl-ex/ A04A04 A24A24 A44A44

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic39 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 ?

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic40 Long-range correlations : JETS ? Jets as a origin of the baseline problem ?? The idea was to try to eliminate pions coming from jet fragmentation from data sample. It can be done by applying an event cut which accepts only events that have no high-pt tracks (jets). HBT analyses where done for three classes of events  all - all events accepted – as a reference  soft – only events without high-p T tracks ( highest-p T < 1.2 GeV/c was chosen)  hard - only events with least one track with p T > 2 GeV/c

mike lisa - Recent developments in femtoscopy at RHIC - ISMD Aug Kroměříž Czech Republic41 D Momentum conservation study with Nexus  Correlation function for pions from events generated with EPOS  No correlation effect included (as BE, FSI)  Background created by mixing particles comming from different events (same procedure like for experiemental CF) No evidence of a problem with baseline of CF ! Nexus, 200 GeV