Heavy Ions Collisions (results and questions) PART II

11

Heavy Ions CollisionsHeavy Ions Collisions(results and questions)(results and questions)

PART IIPART II

Anatoly Litvinenko

[email protected]

2

Some estimations

;ΔyτπR=ΔV

;yΔ1800) - 900(yΔdy

dNNΔ

Form2

==

)8)(1/fm - (4=1600)/200 - (800=)τ)/(πRdy

dN(=ΔV/NΔ)fm/(n 3

Form2=1 3

fm 0.035) - (0.07=λ mb 30=σ

1/nσ=λ

⇒

33

Particle ratios and sParticle ratios and statistical modelstatistical models

44

Particle (hadrons) Particle (hadrons) spectraspectra

A Iordanova (for the STAR Collaboration);J. Phys. G35, p.044008, (2008

:

elliptic flow hydrodynamicselliptic flow hydrodynamics

elliptic flow and space eccentricityelliptic flow and space eccentricity

ε/=A 2v 2

QUESTION IIQUESTION II

Is equilibrium state of hot and dense hadronic matter achieved?

What is the conclusion about it from experiment?

The strong indication that YES.

Some designations

sQGP for strongly-interacting Quark-Gluon Plasma

Commonly accepted:QGP, pQGP,wQGP

for weakly-interacting Quark-Gluon Plasma

Observables and hadronic matter properties

10

KEKETT – CQN Scaling – CQN ScalingKEKETT – CQN Scaling – CQN Scaling

Phys. Rev. Lett. 98, 162301 (2007)

Mesons

Baryons

Quark-Like Degrees of Freedom EvidentQuark-Like Degrees of Freedom Evident

Roy A. Lacey, Stony Brook; Quark Matter 09, Knoxville, TN March 30 - April 4, 2009

11

K. Aamodt et al.(ALICE Collaboration), PRL 105, 252302 (2010)

Elliptic flow – energy Elliptic flow – energy dependancedependance

1212

JET Quenching

Modification of Jet property in AA collisions, because of partons propagating in colored matter, which lose energy.

One of the possible observable

Was predicted in a lot of works. Some of them (not all) are:

1

0)(Pd

J.D.Bjorken (1982), Fermilab – PUB – 82 – 059 - THY.M.Gyulassy and M.Palmer, Phys.Lett.,B243,432,1990.X.-N.Wang, M.Gyulassy and M.Palmer, Phys.Rev.,D51,3436,1995.R.Baier et al., Phys.Lett.,B243,432,1997.R.Baier et al., Nucl.Phys.,A661,205,1999

Jet: A localized collection of

hadrons which come from a fragmenting parton

High pT (> ~2.0 GeV/c) hadrons in NN

h

h

h

abc

dParton distribution functions

Hard-scattering cross-section

Fragmentation Function

h

)Q,x(f 2aaa/A )Q,x(f 2

bbb/B cdabd )Q,z(D 2ddd/h

d,c,b,ahXABd

h

High pT (> ~2.0 GeV/c) hadrons in AA

A

B

h Hard-scattering cross-section

Fragmentation Function

Parton distribution functions

+Numbers of binary collisionsPartonic Energy

Loss

(...)f b/B(...)f a/A cdabd

)Q,z(D 2d

*dd/h

1

0 d

*d

z

z)(Pd

∑→dcba

hXABd,,,

=σ CollN

1515

Nuclear modification factor

is what we get divided by what we expect.is what we get divided by what we expect.

NN

collAAAA d

NdR

σ><σ

=/

From naive picture

AAR

Suppression of high-pt hadrons. Qualitatively.

1616

Nuclear modification factor

NN

collAAAA d

NdR

σ><σ

=/

Normalization on peripheral collisions

pcollAA

ccollAACP )N/d(

)N/d(R

><σ><σ

=

1717

First data in first RHIC RUN

Jet Quenching ! Great!

But (see the next slide)

1818

Nuclear modifications to hard scattering

Large Cronineffect at SPSand ISRSuppression at RHIC

Is the suppression due to the medium?(initial or final state effect?)

RAA (pT ) d2N AA /dpTdTAAd

2 NN /dpTd

Centrality dependance

2020

Au+Au @ sNN

= 200 GeV d+Au @ sNN

= 200 GeV

preliminary

Au+Au @ sNN


= 200 GeV

preliminary

Au+Au @ sNN


= 200 GeV

preliminary

Au+Au @ sNN


= 200 GeV

preliminary

• Nice picture! Isn’t it?

Again Au+Au and d+Au

2121

The matter is so opaque that even The matter is so opaque that even

a 20 GeV a 20 GeV 00 is stopped is stopped..

• Suppression is very strong (RAA=0.2!) and flat up to 20 GeV/c• Common suppression for 0 and it is at partonic level• > 15 GeV/fm3; dNg/dy > 1100

22

.ALICE Collaboration, Physics Letters B 696 (2011) 30.

JET Quenching at LHC

23

ALICE Collaboration, Physics Letters B 696 (2011) 30

JET Quenching at LHC

2424

The matter is so dense that even heavy quarks are stopped

Even heavy quark (charm) suffers substantial energy loss in the matter

The data provides a strong constraint on the energy loss models.

The data suggest large c-quark-medium cross section; evidence for strongly coupled QGP?(3) q_hat = 14 GeV2/fm

(2) q_hat = 4 GeV2/fm


(4) dNg / dy = 1000

2525

If there are any other observables for Jet Quenching?

Correlation of trigger particles 4<pT<6.5 GeV withassociated particles 2<pT<pT,trig

Associated particles

Near side jetTrigger particle

Away side jet

Yes! Back to Back Jets correlation.

2626

In-plane In-plane

Out-of-plane

Out-of-plane

Back to Back Jets correlation.Back to Back Jets correlation.Dependence from reaction plane.Dependence from reaction plane.

2727

Jet tomography

20-60%

STAR Preliminry

20-60%

Back-to-back suppression depends on the reaction plane orientation

In-plane

Out-plane

energy loss dependence energy loss dependence on the path length!on the path length!

2828

The matter is so dense that it The matter is so dense that it modifies the shape of jetsmodifies the shape of jets

• The shapes of jets are modified by the matter.– Mach cone?– Cerenkov?

• Can the properties of the matter be measured from the shape?– Sound velocity– Di-electric

constant• Di-jet tomography is

a powerful tool to probe the matter

2929

Resonances melting (Debye scrinig)

3030

One more results from lattice QCD

heavy-quark screening mass

r/)rexp(~)r(

In EM plasma it is well known Debye screening

T/1~r/1 D

/J -- suppression

3131

The matter is so dense that it melts(?) J/ (and regenerates it ?)

CuCu

200 GeV/c

AuAu

200 GeV/c

dAu

200 GeV/c

AuAuee

200 GeV/c

CuCuee

200 GeV/c

J/’s are clearly suppressed beyond the cold nuclear matter effect

The preliminary data are consistent with the predicted suppression + re-generation at the energy density of RHIC collisions.

Can be tested by v2(J/)?

The matter is so dense that it melts Y.

QM’11

direct photons

3333

• T0max ~ 500-600 MeV !?

T0ave ~ 300-400 MeV !?

3434

SummarySummary

o RHIC has produced a strongly interacting,RHIC has produced a strongly interacting, partonic state of dense matterpartonic state of dense matter

/ 15 3fmGeVBj

3535

SummarySummary

o The matter is so dense that even heavy quarks are stopped




(4) dNg / dy = 1000

3636

SummarySummary

o The matter is so strongly coupled that even heavy quarks flow

3737

SummarySummary

o The matter is so dense that it melts(?) J/ (and regenerates it ?)

3838

SummarySummary

o The matter modifies jets

The matter is hot 3939

The matter may melt but regenerate J/’s

Put the results together

The matter is denseThe matter is strongly coupled

The matter modifies jets

> 15 GeV/fm3

dNg/dy > 1100

Tave = 300 - 400 MeV (?)PHENIX preliminary

4040

Backup slidesBackup slides

January 6, 2002 RHIC/INT Winter Workshop 2002 45

Modeling the Source• Interaction region

Assembly of classical boson emitting sources in space-time region

• The source S(x,p) is the probability boson with p is emitted from xDetermines single-particle momentum spectrum

E d3N/dp3 = d4x S(x,p)

Determines the HBT two-particle correlation function C(K,q) C(K,q) ~ 1 + | d4x S(x,K) exp(iq·x) | 2/| d4x S(x,K) |2

where K = ½(p1 + p2) = (KT, KL), q = p1 – p2

The LCMS frame is used (KL = 0)

• In the hydrodynamics-based parameterizations: assume something about the source S(x,p)Gaussian particle density distribution

Linear flow (rapidity or velocity) profile

Instantaneous freeze-out at constant proper time (“sharp”)

CollN(...)/ aAf (...)/ bBf cdabd

1

0 d

*d

z

z)(Pd )Q,z(D 2

d*dd/h∑

dcba ,,,

(...)/ aAf (...)/ bBf cdabd ),(/2dddh QzD∑

dcba ,,,

4949

Why the collisons of heavy nuclei is interesting?

Let us see on the space – time picture of collision

pre-collision QGP (?) and parton production

hadron production

hadron reinteraction

QCD phase diagram

5050

The QGP in the early universe

5151

What kind of transition is predicted by lattice QCD

52

Dependence on pseudorapidity of charged hadron

S.S. Adler et al. , Phys. Rev. C 71, 034908 (2005)

5353

Theoretical explanation

Comparison to model calculations with and without parton energy loss:

Numerical values range from ~ 0.1 GeV / fm (Bjorken, elastic scattering of partons)~several GeV / fm (BDMPS, non-linear interactions of gluons)

Too many approaches.We need additional data!

2.0~Rand,p~d AuAu8

T

2.0~p/p

Estimation from data

5454

Initial state effects (test experiment d+Au)

Suppression in central Au+Au due to final-state effects

/h

5555

Binary scaling. Is it work?

5656

How about suppression for protons?

pcollccollCP )N/dN/()N/dN(R New

Close to nuclear mod. factor, because no suppression for peripheral coll.

5757

Jets composition as measured by STAR

Kirill Filimonov, QM’04

5959

[w/ the real suppression]

( pQCD x Ncoll) / background Vogelsang/CTEQ6

[if there were no suppression]

( pQCD x Ncoll) / ( background x Ncoll)

Au+Au 200 GeV/A: 10% most central collisions

[]measured / []background = measured/background

Preliminary

pT (GeV/c)

Binary scaling. Is it work?

6060

Theoretical explanation

Comparison to model calculations with and without parton energy loss:

Numerical values range from ~ 0.1 GeV / fm (Bjorken, elastic scattering of partons)~several GeV / fm (BDMPS, non-linear interactions of gluons)

Too many approaches.We need additional data!

6161

If is there space for Color Glass Condensate or only Cronin Effect?

May be. Look at the BRAMS DATA

6363

Observables and space time structureObservables and space time structure of of Heavy ion collisionsHeavy ion collisions

6464


Production of hard particles: jets heavy quarks direct photonsCalculable with the tools of perturbative QCD

6565


Production of semi-hard particles: gluons, light quarks relatively small momentum: make up for most of the multilplicity

cGeVpT / 21

6666


Thermalizationexperiment suggest a fast thermalization (remember elliptic flow)but this is still not undestood from QCD

6767


Quark gluon plasma

6868


Hot hadron gas

6969

Particle ratio and sParticle ratio and statistical modelstatistical models

These models reproduce the ratios of particle yields with only two parameters

One assumes that particles are produced by a thermalized system with temperature T and baryon chemical potential

The number of particles of mass m per unit volume is :

7070

N/ ratio shows baryons enhanced for pT < 5 GeV/c

One more observable. Particle ratios

Heavy Ions Collisions (results and questions) PART II

Documents

Transcript of Heavy Ions Collisions (results and questions) PART II