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International School on: Quark-Gluon Plasma and Heavy Ion Collisions: Past, Present, Future Villa Gualino, Turino, Italy Soft Probes II Christoph Blume University of Heidelberg

Christoph Blume University of Heidelberg

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International School on: Quark-Gluon Plasma and Heavy Ion Collisions: Past, Present, Future Villa Gualino, Turino, Italy Soft Probes II. Christoph Blume University of Heidelberg. Observables. Temperature. Strangeness Resonances. Femtoscopy Fluctuations. Kinetic Freeze-Out. - PowerPoint PPT Presentation

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Page 1: Christoph Blume University of Heidelberg

International School on:

Quark-Gluon Plasma and Heavy Ion Collisions:Past, Present, Future

Villa Gualino, Turino, Italy

Soft Probes II

Christoph Blume

University of Heidelberg

Page 2: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Observables

Page 3: Christoph Blume University of Heidelberg

StrangenessStrangeness

Page 4: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strangeness in Heavy Ion Physics

Strangeness enhancement as a QGP signatureJ. Rafelski and B. Müller, PRL48, 1066 (1982)P. Koch, B. Müller, and J. Rafelski, Phys. Rep. 142, 167 (1986)

Strangeness has to be produced (no s-Quarks in nucleons)

Thresholds are high in hadronic reactions, e.g..: N + N N + K+ + (Ethres 700 MeV)

Fast equilibration in a QGP via partonic processes,e.g. gluon-fusion

⇒ Enhancement of strange particle production in A+A relative to p+p expected (in particular multi-strange particles)

Page 5: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Multiplicities determined bystatistical weights ( chemical equilibrium)⇒

Grand-canonical partition function:

⇒ Parameters: V, T, μB, γS

Details: see F. Becattini’s lecture

Statistical Models

F.Becattini et al., PRC69, 024905 (2004)

A.Andronic et al. PLB673, 142 (2009)

Page 6: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Hadronic Transport Models

Examples:UrQMD

HSD

NEXUS

(AMPT)

(EPOS)

...

Microscopic approachHadronic degrees of freedom

Non-equilibrium

Production mechanisms:Measured and parameterized

cross sections

String-excitation and fragmentation

Medium effects,

Multi-meson fusion,

Mass shifts,

...

Page 7: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strange Particles

Page 8: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Major Strangeness Carriers: Kaons and Lambdas

ss ss

Strangeness Conservation==

Isospin Symmetry

K0 (ds)K0 (ds)K+ (us)K+ (us)

Isospin Symmetry

K- (us)K- (us) K0 (ds)K0 (ds)

(uds) (uds) (uds) (uds)

>>

>>

If baryon density is high

>>>>

Page 9: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Measurement of Charged Kaons via dE/dx

Bethe-Bloch function:

Page 10: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Combination of dE/dx and Time-Of-Flight (TOF)

Page 11: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Weak Decay Topologies

V0 Topology (K0s, Λ):

Ξ- (Cascade) Ω- Topology:

Page 12: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strangeness Production in a Pion-Proton Event

Associated production:

Page 13: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strangeness Production in a Heavy Ion Event

Page 14: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Reconstruction via Decay Topology

NA57NA57

NA49

Page 15: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Armenteros-Podolanski Plot

Page 16: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strangeness Enhancement (SPS)

NA57: JPG32, 427 (2006)

Page 17: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strangeness Enhancement (RHIC)

STAR: PRC77, 044908 (2008)

Page 18: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Enhancement Towards Lower Energies

√sNN (GeV)

Contrary to naive expectation

Same behavior for multi-strange particles?

Page 19: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Particle Ratios in p+p: RHIC and LHC

ALICE: arXiv:1012.3257

Increase of relative strangeness production in p+p with √s

Page 20: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Ξ at Threshold Energies

HADES: PRL103, 132301 (2009)

Expectation for statistical model(Andronic et al.)

Expectation for statistical model(Andronic et al.)

Page 21: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Is it a dominantly partonic effect or can hadronic processes lead to the same fast equilibration?

Multi-meson fusion processesC. Greiner and S. Leupold, J. Phys. G 27, L95 (2001)

Dynamic equilibration at the phase boundary?P. Braun-Munzinger, J. Stachel, and C. Wetterich, Phys. Lett. B 596, 61 (2004)

Hadronization generally a statistical phenomenon?U. Heinz, Nucl. Phys. A 638, 357c (1998), R. Stock, Phys. Lett. B 456, 277 (1999)

Strangeness Enhancement as QGP Signature ?

Page 22: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Energy Dependence of K/π Ratios

Quite sharp maximum in K+/π+ ratio

Indication for phase transition (?)

PRC77, 024903 (2008)arXiv:1007.2613

Page 23: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Energy Dependence of Hyperon/π Ratios

PRC78, 034918 (2008)

Page 24: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Maximum of Relative Strangeness Production

Page 25: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Chemical Freeze-Out Curve

Page 26: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Chemical Freeze-Out in the QCD Phase Diagram

Page 27: Christoph Blume University of Heidelberg

SpectraSpectra

Page 28: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Rapidity Distributions ...

BRAHMS: Au+Au, √sNN = 200 GeV

Page 29: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Landau ...

Prediction: dN/dy is Gaussian of a width given by:

L. D. Landau, Izv. Akad. Nauk. SSSR 17 (1953) 52P. Carruthers and M. Duong-Van, PRD8 (1973) 859

Pion production ~ Entropy Isentropic expansionDescription of the pion gas as a 3D relativistic fluid

p+p Data

Page 30: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Landau ... works also for Heavy Ions

BRAHMS: PRL94, 162301 (2005)

Page 31: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Width of the Φ Rapidity Distribution

Expectation for kaon coalescenceK+ + K- → Φ

PRC78, 044907 (2008)

Page 32: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Radial Expansion and Transverse Momentum Spectra

mT

1/m

T d

N/d

mT

mT

1/m

T d

N/d

mT

No radial flow:exponential spectrum(p+p collisions)

With radial flow:add. boost by expansion (vT)

⇒ blue shifted spectrum

Page 33: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Blast Wave Analysis of Particle Spectra

Central Pb+Pb158A GeV

E. Schnedermann and U. Heinz,PRC50, 1675 (1994)

Page 34: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Energy Dependence of Kinetic Freeze-Out

arXiv:1007.2613

Page 35: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Energy Dependence of 〈mT 〉

NA49: PRC77, 024903 (2008)

Page 36: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Radial Expansion of Strange Particles

What about heavy particles (Ξ, Ω, J/ψ) ?

NA57: JPG32, 2065 (2006)

Page 37: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Radial Expansion of Strange Particles

N. Xu and M. Kaneta, NPA698, 306 (2002) 306.

Particles with low hadronic cross sections: Ξ, Ω, J/ψ

⇒ Not sensitive to flow in hadronic, but maybe to partonic phase

Page 38: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Radial Expansion of Strange Particles

STAR: PRL92, 182301 (2004)

Multi-strange particles sensitive to the partonic flow contribution (?)

Page 39: Christoph Blume University of Heidelberg

ResonancesResonances

Page 40: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Strong decays short lifetimes that can be in the ⇒ order of the fireball lifetime

Examples:K(892) → K+ + π - : cτ = 3.91 fmΦ(1020) → K+ + K- : cτ = 46.5 fm

Σ-(1385) → Λ + π - : cτ = 5.08 fm Λ(1520) → p + K- : cτ = 12.7 fm

Should be sensitive to the late phase of the hadronic fireballRegenerationRescattering of decay products

⇒ Provide information on the time span between chemical and kinetic freeze-out

Resonances

Page 41: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Recombination and Rescattering of Resonances

Hot and dense medium

Particle yields

Particle spectra

Time

K*πK πK

K*

K

π

Picture adapted from C. Markert and P. Fachini

Page 42: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Measurement of Resonances: Σ(1385) and Λ(1520)

STAR: PRC71, 064902 (2005)

Page 43: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Rescattering after Chemical Freeze-Out

STAR: PRC71, 064902 (2005)

Page 44: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Comparison to Chemical Equilibrium Expectation

NA49: pub. in preparation

HGM: F. Becattini et al.

Pb+Pb, √sNN = 17.3 GeVPb+Pb, √sNN = 17.3 GeV

Page 45: Christoph Blume University of Heidelberg
Page 46: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Scaling Properties of the Φ Meson

No scaling with K+ × K-

(coalescence picture)

Scaling with (s-Quarks)2

Φ = ss

K+ s-Quarks∝K- + Λ s-Quarks∝

_

_

Page 47: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

K+/π + and Λ/π – Compared to Statistical Model

A. Andronic et al.,PLB676, 142 (2009)

Page 48: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Energy Dependence of K/π Ratios

Quite sharp maximum in K+/π+ ratio

Indication for phase transition (?)

PRC77, 024903 (2008)

Page 49: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Antibaryon-Baryon Ratios

NA49: PRC78, 034918 (2008)

S = -3

S = -2

S = -1

S = 0

Page 50: Christoph Blume University of Heidelberg

Baryon-Meson-RatiosBaryon-Meson-Ratios

Page 51: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Baryon-Meson Ratio: Λ/K0s

Λ/K0s > 1: Cannot be understood in string fragmentation picture

Page 52: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Hadronization Mechanisms

Fragmentation (Lund model)

String fragments via qq creation

Original parton momentum is divided among resulting partons

_

Quark coalescence

Hadrons form by combining quarksfrom quark soup (QGP)

Would be dominating at intermediate pt

Page 53: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Fragmentation vs Coalescence

Production of baryons favored relative to mesons in coalescence picture

Page 54: Christoph Blume University of Heidelberg

Christoph Blume Villa Gualino, Turino, 7-12 March 2011

Baryon-Meson Ratio: Ω(sss)/Φ(ss)_