ripples of the qgp and the qcd phase diagram...ripples of the qgp and the qcd phase diagram paul...

Ripples of the QGP and the QCD phase diagram

Paul Sorensen June 7th, 2016

RHIC AGS AUM, BES Workshop

What I hope you’ll take away from today

2

Models suggest v3 is a good indicator for the presence of a low viscosity QGP phase Measurements show that for sufficiently central collisions, v3 persists down to the lowest energies at RHIC For peripheral collisions however, we find that v3 disappears in lower energy collisions The energy dependence of v3 and other observables seems to suggest an anomalously low pressure in the matter created in heavy ion collisions with √sNN near 15-20 GeV

Major Advances in Early RHIC Years

3

First years of Au+Au → Perfect fluidity → Suppression of high pT particles → Observation of the long-range correlations (ridge)

First d+Au Run → Opacity of the plasma phase → Evidence of gluon saturation

First run with Cu+Cu → Importance of fluctuations

σy2

σx2 σx

2σy2

Principal axis transformation

Smaller system revealed importance of initial state fluctuations

PH

OB

OS

, Phys. R

ev. Lett. 98, 242302 (2007)

accounting for fluctuations

3

STA

R, P

hys. Rev. C

. 80, 064912

Standard Model of the Little Bangs

4

Long range correlations understood as arising from initial state density fluctuations. Conversion into momentum space requires a low η/s plasma

Sensible to express as vn. Jettiness/non-flow subdominant until higher pT

5

Quark Gluon Plasma

Breaking of chiral symmetry in QCD generates 99% of the visible mass of the universe. Is chiral symmetry restored in these collisions?

At low density, the phase transition between QGP and hadrons is smooth. Is there a 1st order transition and a critical point at higher density?

But first, is a QGP created in the lower energy collisions?

a unique capability -- a unique opportunity

Studying the Phases of QCD with RHIC

Do We Create QGP at Lower Energies?

The minimum εcτ for QGP formation is between 0.6-1.8 GeV/fm2

BES-I exploratory scan was carried out to shed light on this question

Energy density measurements from exploratory scan: BES-I 2010-2014

6

A. Adare et al. Phys. Rev. C 93, 024901

Head-on Collisions Npart~350

Grazing Collisions small Npart

well above

too close to call

Elliptic Flow: 7.7 GeV to 2.76 TeV

Surprisingly consistent as the energy changes by a factor ~400 Initial energy density changes by nearly a factor of 10 No evidence from v2 for a turn off of the QGP How sensitive is v2 to QGP?

7

Rat

io

v

2{4}

pT (GeV/c)

coordinate-space anisotropy into momentum-space

0 1 2 3

0.6

0.8

1.0

1.2

1.4

0.0

0.1

0.2 STA

R C

ollaboration, Phys. R

ev. C 86 (2012) 54908

8 8

Models show that higher harmonic ripples are more sensitive to the existence of a QGP phase

In models, v3 goes away when the QGP phase disappears

← n=2 →

J. Auvinen, H. Petersen, Phys. Rev. C 88, 64908

t = 0 fm t = 2.5 fm t = 5 fm B. Schenke et.al., Phys. Rev. C 85, 024901

Elliptic n=2 flow (image of an atomic fermi gas)

All harmonic flow (QGP simulation)

Do We Create QGP at Lower Energies?

9Full azimuthal tracking: |η| < 1.0 and pT > 0.2 GeV/c

√snnGeV Year Evts(106)

200 2011 350

62.4 2004 4

39 2010 10

27 2011 20

19.6 2011 16

14.5 2014 18

11.5 2010 3.5

7.7 2010 3

Detector and Data Sets STAR Collaboration, Phys. Rev. Lett. 116, 112302

Correlations Functions

10

|η∆|

00.5

11.5 φ∆1−

0 12 3

4

0.998

1

1.002

1.004

Au+Au 7.7 GeV: 0-5%)η∆,φ∆C(

|η∆|

00.5

11.5 φ∆1−

0 12

3 4

0.998

1

1.002

Au+Au 11.5 GeV: 0-5%

|η∆|

00.5

11.5 φ∆1−

0 12

3 4

0.998

1

1.002

Au+Au 14.5 GeV: 0-5%

STAR Preliminary

|η∆|

00.5

11.5 φ∆1−

0 12

3 4

0.999

1

1.001

1.002

1.003

1.004

Au+Au 19.6 GeV: 0-5%

|η∆|

00.5

11.5 φ∆1−

0 12

3 4

0.999

1

1.001

1.002

1.003

1.004

Au+Au 27 GeV: 0-5%

|η∆|

00.5

11.5 φ∆1− 0

12

3 4

0.999

1

1.001

1.002

1.003

1.004

Au+Au 39 GeV: 0-5%

L. Song; QM2015

vn2 2{ } Δη( ) = cosn ϕ1 −ϕ2( ) =

dNdΔϕ

cos nΔϕ( )d∑ Δϕ dNdΔϕ d∑ ΔϕCorrelations can be decomposed into ∆η dependent harmonics

3rd Harmonic Decomposition

11 11

0.1−

0

0.1

0.2

0.3

0.4

0.5

0.6

3−10× =200 GeVNNs

Short-rangeLong-range (ridge)

UrQMD

|0.2 GeV; |T

all charge; p

)η∆({2}23v

0

0.2

0.4

0.6

0.8

1)η∆({2}23v

η∆0 0.5 1 1.51−

0

1

2

3

4 )η∆({2}23v

=27 GeVNNs

)η∆({2}23v

)η∆({2}23v

η∆0 0.5 1 1.5

)η∆({2}23v

=14.5 GeVNNs

)η∆({2}23v

)η∆({2}23v

η∆0 0.5 1 1.5

)η∆({2}23v

=7.7 GeVNNs

0-5

% C

entra

l

)η∆({2}23v

20-3

0%

Centra

l

)η∆({2}23v

η∆0 0.5 1 1.5

60-7

0%

Centra

l

)η∆({2}23vSTAR Collaboration, Phys. Rev. Lett. 116, 112302

∆η Integrated Results

12 12

27 GeV

vn2 2{ }=

vn2 2{ } Δηi( )−δi( ) dNidΔϕii

∑dNidΔϕii

∑

Integrate over the whole ∆η range but subtract off short-range contribution

Acceptance and efficiency corrected results for pT>0.2 GeV and η

Centrality Dependence

0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

13 13

Npart scales out trivial 1/N system size dependence: linear superposition of N+N STAR Collaboration, Phys. Rev. Lett. 116, 112302

0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7


14 14

Centrality dependence well understood in terms of initial geometry: P.S. et.al., Rise and Fall of the Ridge, Phys.Lett. B705 (2011) 71-75

STAR Collaboration, Phys. Rev. Lett. 116, 112302


0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

15 15

Centrality dependence well understood in terms of initial geometry: P.S. et.al., Rise and Fall of the Ridge, Phys.Lett. B705 (2011) 71-75

ν

1 2 3 4 5 6 70

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1A

200 GeV

Au+Au

Data

Model

∝ vn2

= 2nbin/npart



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

16 16



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

17 17



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

18 18



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

19 19



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

20 20



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

21 21



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

22 22

STILL THERE!



0 100 200 300

0

0.02

0.04

0.06

0.08

0.1

AMPT Default; 7.7 GeV

{2}23vpartN

partN

=200 GeVNN

s 62.4 39 27 19.6 14.5 11.5 7.7

23 23


The Ridge and v3 in Smaller Systems

24

Ridge correlations in small systems; considered by some to be a crisis… Can we turn off the QGP?

24

Disappearance of v3

25 25

0 50 100 150 200

0

0.01

0.02

0.032{2}3vpartN

partN

STAR Preliminary

(GeV)NNs 200 14.5 11.5

η∆0 0.5 1 1.50.002−

0

0.002)η∆(23v

= 11.5 GeVNNs

= 49〉part N〈


Energy Dependence

26 26

10 210310

0

0.0002

0.0004

0.0006

0.0008

0.001 {2}23v

(GeV)NNs

0-5% 10-20% 30-40% 50-60%

While the 3rd harmonic grows as ~log(√s) at higher energy, it is nearly independent of energy below 20 GeV.

increase from

ever larger g

radients

in higher mul

tiplicity collisi

ons? flat even as multiplicity

grows!

Pb+Pb ALICE


27 27

10 210310

0.04

0.06

0.08

0.1

0.12

0.14

3−10×

ch,PP/n{2}23v

(GeV)NNs

0-5% 10-20% 30-40% 50-60%

Higher energy collisions producing more particles and higher pressure should more effectively convert fluctuations into v3.

Deviations from that expectation could be indicative of interesting trends like a slowing of the speed of sound. What does v32/Nch look like?

Anomalies in the Pressure?


28

v1 for both p & net-p qualitatively resemble collapse signature

Calculations with more sophisticated treatments of early times are needed

STAR, PRL 112, 162301 (2014); arXiv:1401.3043

Anomalies in the Pressure?

H. Stoecker, Nucl. Phys. A 750, 121 (2005)

29

Are Data Indicative of Anomalies in the Pressure? )

2 (

fm2 si

de

- R

2 out

R

6

8

10

12

0.5 0.4 0.3 0.2 0.1

(GeV)B

µ

= 0.26 GeVT

0%-5%; m

/dy

1dv

0

0.01

10%-40%; net-proton

(GeV)NNs10 210 310

ch,p

p/n

{2}

2 3v

0.04

0.05

0.06

0.07

0.08

>0.2 GeVT

0%-5%; p

Maximum in lifetime?

Minimum in pressure?

Region of interest √sNN~20 GeV, however, is complicated by a changing B/M ratio, baryon transport dynamics, longer nuclear crossing times, etc. Requires concerted modeling effort: the work of the BEST collaboration is essential

Mapping the region of interest: BES-II

30

0 0.1 0.2 0.3 0.4 0.5

Mill

ion E

vents

10

210

310

7.7

9.1

11.5

14.5

19.6

273962.4

200

(GeV)NNs

Cu

rre

nt

Da

ta S

ets BES-II

0 0.1 0.2 0.3 0.4 0.5

/dy

1d

v

0

0.01

0.02net-proton

10%-40% BES-I

10%-15% BES-II

(GeV)B

µ

0 0.1 0.2 0.3 0.4 0.5

net-

pro

ton

2σ

κ

0

1

2

3

0%-5% Au+Au; |y|

What I hope you took away from today

31

Models suggest v3 is a good indicator for the presence of a low viscosity QGP phase Measurements show that for sufficiently central collisions, v3 persists down to the lowest energies at RHIC For peripheral collisions however, we find that v3 disappears in lower energy collisions: Turn off of the QGP The energy dependence of v3 and other observables seems to suggest an anomalously low pressure in the matter created in heavy ion collisions with √sNN near 15-20 GeV

Thanks

32

Disappearance of v3

33

40-50% 50-60% 60-70% 70-80%

14.5

GeV

11

.5 G

eV

7.7

GeV

All Centralities

34 34

10 210 310

0

0.0002

0.0004

0.0006

0.0008

0.001

{2}23v

(GeV)NNs

0-5% 5-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-70% 70-80%

10 210 310

0

0.0002

0.0004

0.0006

0.0008

0.001

{2}23v

(GeV)NNs

0-5% 5-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-70% 70-80%

Increasing Multiplicity

35 35

(GeV)NNs10 210 310

01

2

34

5

67

89

10

part0.5N/dchdN = ch,PPn

€

0.722 sNN( )0.310

€

0.78log sNN( ) − 0.40

Independent of energy range, one expects higher energy collisions producing more particles to more effectively convert geometry fluctuations into v3.

Deviations from that expectation could be indicative of interesting trends like a softening of the equation of state. What does v32/Nch look like?

We parameterize the worlds data and take the ratio

Softening?

36 36

10 210310

0.04

0.06

0.08

0.1

0.12

0.14

3−10×

ch,PP/n{2}23v

(GeV)NNs

0-5% 10-20% 30-40% 50-60%

Softening?

37 37

10 210 310

0.04

0.06

0.08

0.1

0.12

0.14

0.163−10×

ch,PP/n{2}23v

(GeV)NNs

0-5% 5-10% 10-20% 20-30% 30-40% 40-50%

Local minima is present for all centralities between 0 and 50%

Lattice EOS

38 38

50 100 150 200 250 3000

20

40

60

80

100

Graph

1 10 2100.1

0.15

0.2

0.25

0.3

Graph

The same EOS: p/ε vs ε

Plotting format matters! especially when looking for trends in pressure vs energy density

What about v2?

39 39

0 100 200 3000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.82{2}2vpartN

partN

STAR Preliminary

=200 GeVNNs 62.4 39 27 19.6 14.5 11.5 7.7

10 210 310 4100

0.0005

0.001

0.0015

0.002

0.0025ch,PP/n{2}22v

(GeV)NNs

STAR Preliminary

20%-30% 30%-40% 40%-50%

pT Dependence of the Decomposition

40 40

HBT/Coulomb prominent at low pT

Jets appear at higher pT

Short range correlations can be subtracted by looking at the ∆η dependence

Correlations in Small Systems

41

Hydro-based dynamic calculations also start to agree with the data for central p+Pb collisions

Surprisingly smooth continuity across multiplicities from 30 to 3000 (but what should we have expected?)

41

v2 from 2.76 TeV down to 7.7 GeV At low energy, NCQ dependence holds for particles but not anti-particles

42

2v

0

0.1

0.211.5 GeV a)

p

-

-

++Ks0K

0 1 2 3

(B)-

fit2v 0

0.05

62.4 GeV b)

Au+Au, 0-80%

0 1 2 3

0-mTm

11.5 GeV c)

p

+

+

-

-Ks0K

0 1 2 3)2 (GeV/c

62.4 GeV d)

-sub EP

0 1 2 3

particles anti-particles

10 210 310 4100

0.020.040.060.08

0.10.120.140.160.180.2

-310!

{2}23 v)/dch

2(dNpartN

(GeV)NNs

STAR Preliminary

20-30%30-40%40-50%

slope of net-proton v1

Non-monotonic trends in pressure?

PH ENIXpreliminary

43

Collision Energies (GeV): 7.7 9.1 11.5 14.5 19.6

Chemical Potential (MeV): 420 370 315 260 205

Observables Millions of Events Needed

RCP up to pT 4.5 GeV NA NA 160 92 22

Ellip3cFlowofφmeson(v2) 100 150 200 300 400

Local Parity Violation (CME) 50 50 50 50 50

Directed Flow studies (v1) 50 75 100 100 200

asHBT (proton-proton) 35 40 50 65 80

net-proton kurtosis (κσ2) 80 100 120 200 400

Dileptons 100 160 230 300 400Proposed Number of Events: 100 160 230 300 400

Statistics Needed in BES phase II

44

ripples of the qgp and the qcd phase diagram...ripples of the qgp and the qcd phase diagram paul...

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