What do we see ? Kai Schweda 1/53 LHC lecture, Heidelberg, 1 Feb, - PowerPoint PPT Presentation

What do we see ? Kai Schweda 1/53 LHC lecture, Heidelberg, 1 Feb, 2010

Hadron spectra from RHIC p+p and Au+Au collisions at 200 GeV Full kinematic reconstruction of (multi-) strange hadrons in large acceptance of STAR White papers - STAR: Nucl. Phys. A757, p102. Kai Schweda 2/53 LHC lecture, Heidelberg, 1 Feb, 2010

Outline  Introduction  Collectivity at RHIC - transverse radial flow - tranverse elliptic flow - extracting η /s  Heavy − quark dynamics  Outlook Kai Schweda 3/53 LHC lecture, Heidelberg, 1 Feb, 2010

HI - Collision History  T c(ritical) : quarks and gluon ⇒ hadrons, T c(ritical) = 160 MeV  T ch(emical) : hadron abundancies freeze out  T fo : particle spectra freeze out Plot: R. Stock, arXiv:0807.1610 [nucl-ex]. Kai Schweda 4/53 LHC lecture, Heidelberg, 1 Feb, 2010

Chemical Freeze-out Model Refs. J.Rafelski PLB(1991)333 Hadron resonance ideal gas P. Braun-Munzinger et al., nucl-th/0304013 Density of particle i Q i : 1 for u and d, -1 for u and d T ch : Chemical freeze-out temperature µ q : light-quark chemical potential s i : 1 for s, -1 for s µ s : strange-quark chemical potential : spin-isospin freedom g i m i : particle mass V : volume term, drops out for ratios! γ s : strangeness under-saturation factor µ B = 3 µ q µ S = µ q - µ s All resonances and unstable particles are decayed Compare particle ratios to experimental data Kai Schweda 5/53 LHC lecture, Heidelberg, 1 Feb, 2010

Example At RHIC, Au+Au @ 200 GeV: T ch = 160 MeV, µ B = 20 MeV Anti-proton to proton ratio: Volume drops out Pbar/p = exp[(-20 MeV - 20 MeV)/160 MeV] = 0.77 ψ ’/J/ ψ = (m ψ ’ /m J/ ψ ) 2 * K 2 (m ψ ’ /160 MeV)/ K 2 (m J/ ψ /160 MeV) = 3% Experimentally: measure particle yields and ratio to extract T ch and µ B Kai Schweda 6/53 LHC lecture, Heidelberg, 1 Feb, 2010

Hadron Yield − Ratios 1) At RHIC: T ch = 160 ± 10 MeV µ B = 25 ± 5 MeV 2) γ S = 1. ➠ The hadronic system is thermalized at RHIC. 3) Short-lived resonances show deviations. ➠ There is life after chemical freeze-out. RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184; Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013. Kai Schweda LHC lecture, Heidelberg, 1 Feb, 2010

Chemical Freeze-Out vs Energy With increasing energy: • T ch increases and saturates at T ch = 160 MeV • Coincides with Hagedorn temperature • Coincides with early lattice results  limiting temperature for hadrons, T ch ch ≈ 160 MeV ! µ B decreases, µ B = 1MeV at LHC •  Nearly net-baryon free ! A. Andronic et al., NPA 772 (2006) 167. Kai Schweda 8/53 LHC lecture, Heidelberg, 1 Feb, 2010

QCD Phase Diagram Kai Schweda 9/53 LHC lecture, Heidelberg, 1 Feb, 2010

Baryon Ratios With increasing energy: • Baryon ratios approach unity At LHC, pbar / p ≈ 0.95 •  with increasing collision energy, production of matter and anti-matter gets closer Compilation: N. Xu Kai Schweda 10/53 LHC lecture, Heidelberg, 1 Feb, 2010

‘Elementary’ p+p Collisions  Low multiplicities  use canonical ensemble: Strangeness locally conserved!  particle yields are well reproduced  Strangeness not equilibrated ! ( γ s = 0.5) Statistical Model Fit: F. Becattini and U. Heinz, Z. Phys. C 76, 269 (1997). Kai Schweda 11/53 LHC lecture, Heidelberg, 1 Feb, 2010

HI - Collision History  T c(ritical) : quarks and gluon ⇒ hadrons, T c(ritical) = 160 MeV  T ch(emical) : hadron abundancies freeze out, T ch(emical) = 160 MeV  T fo : particle spectra freeze out Plot: R. Stock, arXiv:0807.1610 [nucl-ex]. Kai Schweda 12/53 LHC lecture, Heidelberg, 1 Feb, 2010

Collective Flow Kai Schweda LHC lecture, Heidelberg, 1 Feb, 2010

Pressure, Flow, … Pressure, Flow, … Pressure, Flow, Pressure, Flow, Thermodynamic identity � � = + d dU pdV σ – entropy p – pressure U – energy V – volume τ = k B T, thermal energy per dof In A+A collisions, interactions among constituents and density distribution lead to: pressure gradient ⇒ collective flow ⇔ number of degrees of freedom (dof) ⇔ Equation of State (EOS) ⇔ cumulative – partonic + hadronic Kai Schweda 14/53 LHC lecture, Heidelberg, 1 Feb, 2010

Momentum Distributions* Momentum Distributions* Momentum Distributions* Momentum Distributions* π • Typical mass ordering in inverse slope T th =107±8 [MeV] from light π to heavier Λ ] < β t >=0.55±0.08 [c] c ) -1 π n=0.65±0.09 • Two-parameter fit describes yields of [(GeV/ K (dE/dx) χ 2 /dof=106/90 π , K, p, Λ K (kink) solid lines: fit range p T th = 90 ± 10 MeV • K (dE/dx) K (kink) dy < β t > = 0.55 ± 0.08 c • N T dp p d  Disentangle π 2 collective motion from thermal Λ Λ 2 random walk p T [GeV/ c ] *Au+Au @130 GeV, STAR Kai Schweda 15/53 LHC lecture, Heidelberg, 1 Feb, 2010

(anti-)Protons From RHIC (anti-)Protons From RHIC (anti-)Protons From RHIC (anti-)Protons From RHIC Au+Au@130GeV Au+Au@130GeV Au+Au@130GeV Au+Au@130GeV More central collisions = 2 + 2 m p mass T T Centrality dependence: - spectra at low momentum de-populated, become flatter at larger momentum ➠ stronger collective flow in more central tronger collective flow in more central coll oll.! .! STAR: Phys. Rev. C70, 041901(R). Kai Schweda 16/53 LHC lecture, Heidelberg, 1 Feb, 2010

Thermal Model + Radial Flow Thermal Model + Radial Flow Thermal Model + Radial Flow Thermal Model + Radial Flow Fit Fit Fit Fit Source is assumed to be: – in local thermal equilibration: T fo – boosted in transverse radial direction: ρ = f( β s ) boosted E.Schnedermann, J.Sollfrank, and U.Heinz, Phys. Rev. C48 , 2462(1993) 3 N E d � � (u µ p µ )/T fo p random 3 � d � µ � e dp � � � � � m T cosh � p T sinh � dN � R � � � � � rdrm T K 1 I 0 � � � � m T dm T � T fo � � T fo � 0 � � � r � 1 � T � = tanh � T = � S � = 0.5, 1, 2 � � � � R Kai Schweda 17/53 LHC lecture, Heidelberg, 1 Feb, 2010

D-meson collective flow Large collective flow velocity ⇒ Spectrum moves to larger momentum Kai Schweda 18/53 LHC lecture, Heidelberg, 1 Feb, 2010

HI - Collision History  T c(ritical) : quarks and gluon ⇒ hadrons, T c(ritical) = 160 MeV  T ch(emical) : hadron abundancies freeze out, T ch(emical) = 160 MeV  T fo : particle spectra freeze out, T fo ≈ 100 MeV : π , K, p Plot: R. Stock, arXiv:0807.1610 [nucl-ex]. Kai Schweda 19/53 LHC lecture, Heidelberg, 1 Feb, 2010

Kinetic Freeze-out at RHIC φ 1) Multi-strange hadrons φ 1) Multi-strange hadrons Ω and Ω freeze-out earlier freeze-out earlier and π , ( π than ( , K K , , p p ) ) than   Collectivity prior to Collectivity prior to hadronization hadronization 2) Sudden single freeze-out*: 2) Sudden single freeze-out*: Resonance decays lower T Resonance decays lower T fo fo π , for ( π , K K , , p p ) ) STAR Preliminary for (  Collectivity prior to Collectivity prior to  hadronization hadronization   Partonic Partonic Collectivity ? ? Collectivity STAR Data: Nucl. Phys. A757, (2005 102), *A. Baran, W. Broniowski and W. Florkowski, Acta. Phys. Polon. B 35 (2004) 779 . Kai Schweda 20/53 LHC lecture, Heidelberg, 1 Feb, 2010

Anisotropy Parameter v 2 coordinate-space-anisotropy ⇔ momentum-space-anisotropy y p y p x x � = � y 2 � x 2 � v 2 = cos2 � , � = tan � 1 ( p y ) � y 2 + x 2 � p x Initial/final conditions, EoS, degrees of freedom

v 2 in the Low-p T Region P. Hu ovinen, private communications, 2004 - v 2 approx. linear in p T , mass ordering from light π to heavier Λ ➠ characteristic of hydrodynamic flow ! ➠ sensitive to equation of state Kai Schweda 22/53 LHC lecture, Heidelberg, 1 Feb, 2010

Non-ideal Hydro-dynamics � s < 6/4 �  finite shear viscosity η reduces elliptic flow String theory predicts:  many caveats, e.g.: - initial eccentricity ε (Glauber, CGC, …) η /s > 1/4 π - equation of state - hadronic contribution to η /s M.Luzum and R. Romatschke, PRC 78 034915 (2008); P. Romatschke, arXiv:0902.3663. Kai Schweda 23/53 LHC lecture, Heidelberg, 1 Feb, 2010

Elliptic Flow vs Collision Energy Glauber initial conditions  Centrality dependence: - initial eccentricity ε - overlap area S  Collision energy dep.: - multiplicity density dN ch /dy  in central collisions at RHIC, hydro-limit seems reached ! NA49, Phys. Rev. C68, 034903 (2003); STAR, Phys. Rev. C66, 034904 (2002); Hydro-calcs.: P. Kolb, J. Sollfrank, and U. Heinz, Phys. Rev.C62, 054909 (2000). Kai Schweda 24/53 LHC lecture, Heidelberg, 1 Feb, 2010

v 2 of φ and multi-strange Ω  Strange-quark flow - partonic collectivity at RHIC ! QM05 conference: M. Oldenburg; nucl-ex/0510026. Kai Schweda 25/53 LHC lecture, Heidelberg, 1 Feb, 2010

Collectivity, Deconfinement at RHIC - v 2 , spectra of light hadrons and multi-strange hadrons - scaling with the number of constituent quarks At RHIC, it seems we have: ➪ Partonic Collectivity Deconfinement ➪  Thermalization ? PHENIX: PRL 91 , 182301(03) STAR: PRL 92 , 052302(04) S. Voloshin, NPA715, 379(03) Models: Greco et al, PR C68 , 034904(03) X. Dong, et al., Phys. Lett. B597 , 328(04). …. Kai Schweda 26/53 LHC lecture, Heidelberg, 1 Feb, 2010