Soft physics at RHIC
Hiroshi Masui,
University of Tsukuba!

Fall KPS meeting, Nov. 2013

H. Masui, KPS, Nov/1/2013!1 /20RHIC heavy ion collisions
√sNN
(GeV)

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

200
130
62.4
39
27
22.5
19.6
STAR
only

11.5
7.7

Test
run

5.0
Au+Au

Cu+Cu

d+Au

U+U & Cu+Au
H. Masui, KPS, Nov/1/2013!2 /20RHIC heavy ion collisions
√sNN
(GeV)

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

200
130
62.4

• Variety of collision systems (d to U), wide

39

range (5-200 GeV) of collision energies

27
22.5
19.6
STAR
only

11.5
7.7

Test
run

5.0
Au+Au

Cu+Cu

d+Au

U+U & Cu+Au
H. Masui, KPS, Nov/1/2013!2 /20RHIC heavy ion collisions
√sNN
(GeV)

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

200
130
62.4

• Variety of collision systems (d to U), wide

39

range (5-200 GeV) of collision energies• QGP properties at top RHIC energy

27

22.5
19.6
STAR
only

11.5
7.7

Test
run

5.0
Au+Au

Cu+Cu

d+Au

U+U & Cu+Au
H. Masui, KPS, Nov/1/2013!2 /20RHIC heavy ion collisions
√sNN
(GeV)

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

200
130
62.4

• Variety of collision systems (d to U), wide

39

range (5-200 GeV) of collision energies• QGP properties at top RHIC energy• Search for QCD critical point & phase

27

22.5
19.6
11.5

boundary by Beam Energy Scan (BES)
program phase-I
STAR
only

7.7
Test
run

5.0
Au+Au

Cu+Cu

d+Au

U+U & Cu+Au
H. Masui, KPS, Nov/1/2013!2 /20RHIC heavy ion collisions
√sNN
(GeV)

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

200
130
62.4

• Variety of collision systems (d to U), wide

39

range (5-200 GeV) of collision energies• QGP properties at top RHIC energy• Search for QCD critical point & phase

27

22.5
19.6
11.5

boundary by Beam Energy Scan (BES)
program phase-I
STAR➡ Study structure of QCD phase diagram

only

7.7

Test
run

5.0
Au+Au

Cu+Cu

d+Au

U+U & Cu+Au
H. Masui, KPS, Nov/1/2013!2 /20Multi-particle correlations• Powerful tools to study the bulk properties of the system‣ Azimuthal anisotropy!
!

Initial geometry (+fluctuations), shear viscosity!
Local parity violation, chiral magnetic effect‣ Femtoscopy (identical bosons)!

‣ Conserved charge fluctuations!

Source size, geometrical anisotropy
at freeze-out
Susceptibility, QCD critical point!

• I’m going to review the recent correlation measurements fromRHIC

H. Masui, KPS, Nov/1/2013!3 /20PHENIX• Fast triggers‣ Hard probes by electrons &photons• TOF + EMC + Aerogel‣ hadrons• Forward beam counters(BBC, MPC, RXN)

‣ support measurements ofazimuthal anisotropy‣ large pseudorapidity gap

reduces ‘non-flow’ effects• VTX, FVTX

‣ heavy flavors

H. Masui, KPS, Nov/1/2013!4 /20STARTime Of Flight

Muon Telescope Detector

Time Projection Chamber

Heavy Flavor Tracker• Large acceptance - Time Projection Chamber (TPC)• PID capabilities have been (will be) significantly improved‣ TOF (2009-) - charged hadrons‣ MTD (2013-) - muons‣ HFT (from 2014) - heavy flavors
H. Masui, KPS, Nov/1/2013!5 /20coordinate space

tio
n

pl
an
e

Ψ

RP

momentum space

ac

Py

Re

Y
Z

X

Px

Pz

Azimuthalanisotropy
H. Masui, KPS, Nov/1/2013!6 /20Flow in d+Au ?

FIG. 3: (color online) The nth-order pair anisotropy, cn , ofthe central collision excess as a function of associated particle paT . PHENIX (filled [red] circles) c2 and (open [black]circles) c3 are for 0.5 < ptT < 0.75 GeV/c, 0.48 < |∆η| < 0.7
and ATLAS (filled [green] squares) c2 [9] are for 0.5 < ptT <PHENIX,
arXiv:1303.1794v1[nucl-ex]
4.0 GeV/c,
2 < |∆η| < 5.

|Δη|=0.48-0.7

local maximum in colcorrelations at ∆φ
~0
c
●

Th
The Central-b
correlation is do
TCentral-forward(dΔη>3dominate by c1dcoc
contribution
● W
go
loc
co
●

• Large v in 0-5% d+Au collisions at √s = 200 GeV• Near side correlation in 0-5% on Au-going side

FIG. 4:(color online)2 Charged hadron second-orderanisotropy, v2 , as a function transverse momentum for (filled[blue] circles) PHENIX and (open [black] circles) ATLAS [9].
Also shown are a hydrodynamic calculation [14, 25] for (up√per [blue] curve) d+Au collisions at
sN N = 200 GeV
and (lower [black] curve) 0–4% central p+Pb collisions at√
sN N = 4.4 TeV.

NN

‣ No near side peak on d-going side●

PHENIX, IS2013

●

Th
do
co

‣ Need to understand away side jet contributions to extract vn• Interesting to see the centrality dependence

correlations. Here, signal is measured at midrapidity,
but it is natural to ask if previous PHENIX rapidity separated correlation measurements [18] would have been
sensitive‣ to a signal of this magnitude, if it is present.
The maximum c2 observed here is approximately a 1%
modulation about the background level. Overlaying a
modulation of this size on the conditional yields shown in(Two-particle) non-flow scales like 1/N

H. Masui, KPS, Nov/1/2013!7 /20Geometry control
Collisions with deformed nuclei; U+ U

Asymmetric collisions; Cu + Au

body-body collision

tip-tip collision* Average deformation of Uranium ~ 28%
Cu ~ 16%, Au ~ -13%

• Test the relation between initial geometry and final
momentum anisotropy‣ Achieve higher density in deformed collisions with the same energy‣ Path length dependence‣ Finite odd harmonics from geometry overlap‣ Control magnetic field (test chiral magnetic effect)
H. Masui, KPS, Nov/1/2013!8 /20nce!between!Au+Au!and!U+U?!
Results

PHENIX, RHIC&AGS users meeting

ancels out multiplicity independent efficiency
Slope of v2 for multiplicity dependence0

v1 x 10

Slope parameter

0.4

STAR!Preliminary!
STAR
Preliminary-0.06√sNN = 193 GeV
STAR, APS2013

10-1

U+U data
Au+Au datazdc (% )U+U glauber
Au+Au glauber

1

Centrality percentile by ZDC• The!U+U!v2!shows!a!stronger!mulBplicity!dependence.!
0.1%
central• Amostlinearfit for v2, the slope parameter!
• The!diﬀerences!in!the!slope!parameters!between!Au+Au!
and!U+U!increase!in!more!central!collisions!
• Compare!with!eccentricity!calculated!from!glauber!
2
simulaBons(!scaled!down!0.2!for!UU!and!0.25!for!AuAu!
!!!!!!to!match!the!experimental!v2!)!

(a)40-50%

(b)

0.4

0.4

0.3

0.3

0.2

0.2

0.2

0.1

0.1

0.1

0.0

0.0

0.0

v1 (Ψ1,SMD)

0.3

0.0

-0.04

0.4

v1 x 10

Slope

-0.02

30-40%

0.5

1.0

1.5

2.0

50-60%

2.5

3.0

(c)

0.5

1.0

1.5

2.0

2.5

30-60%

3.0

(d)

0.4

Cu+Au sNN = 200 GeV

0.4

0.3

0.3

0.3

0.2

0.2

0.1

0.1

0.1

0.0

0.0

0.0

 

0.0 0.5 1.0 1.5 2.0 2.5 3.0
p (GeV/c)T

0.2

0.5 1.0 1.5 2.0 2.5 3.0
p (GeV/c)T• v slope shows clear difference between Au+Au and U+U‣ super central U+U could enhance tip-tip collisions•

used!to!trigger!on!spectator!neutrons!
13!
Large v @ mid-rapidity in
Cu+Au (not observed in Au+Au)
1‣ also for pions. Need more statistics for protons
H. Masui, KPS, Nov/1/2013!9 /20%

unted for by mean field potentials where the K and
eel an attractive force while the Kþ and p feel alsive force.

compared to the particles. At sNN ¼ 11:5 GeV
difference becomes negative for the antiparticle(mT % m0 ) <1 GeV=c2 but the overall trend is still si
pﬃﬃﬃﬃﬃﬃﬃﬃ
to the one of the particles andSTAR
to PRL110,sNN 143201¼ 62:4
GeV.
(2013),Break down of NCQ scaling

PRC88, 014902 (2013)

v2

0.2

11.5 GeV

62.4 GeV

(a)

(b)

0.1

p
Λ
Ξ
Ω

v2(B)-fit

0

Au+Au, 0%-80%

11.5 GeV

p
Λ
+
Ξ
+
Ω

(c)

-

π
K
0
Ks
φ

η-sub EP

62.4 GeV

(d)

π+
+
K
0
Ks
φ

0.05
0
-0.05
0

•

1

2

3

0

1

2

3

0

1

2

3

0

1

2

3

mT-m0 (GeV/c2)

Numberof Constituent
scalingof v2 of reduced transverse mass (mT % m0 ) for par
3 (color online).
The upper
panels depict the Quark
elliptic flowv2 as a function
pﬃﬃﬃﬃﬃﬃﬃﬃ
11:5 and 62.4 GeV. Simultaneousnd (b), and‣ antiparticles,
(c)
and
(d),
in
0%–80%
centralAuþ
Au
collisionsat
NN ¼
Indication of deconfinement at early stage of heavy sioncollisions
mesons except the pions are shown as the dashed lines. The difference of the baryon v2 and the meson fits are shown in thels.
Meson-baryon splitting at 62.4 GeV - NCQ scaling of v2•‣ No difference between particles and anti-particles
142301-5• Meson-baryon splitting is gone at 11.5 GeV• NCQ scaling is broken between particles and anti-particles
H. Masui, KPS, Nov/1/2013!10 /20

(2)rom their
2/3, b̈x (3.
dths #x(t)ne-dimenzed, zeroributions,
As shown
fits to theood. Thisotentially
FIG. 13 The homogeneity lengths can be measured in three independent
directions. By convention and convenience, these are chosen along thebeam axis (“long”), along the transverse motion of the pions (“out”)
and perpendicular to these two directions (“side”). See text for details.

( x, y, z.
stribution
is deterfunction) $ 0z2z2
al radii ofe proporour trap,
amic exstribution

FIG. 13 The homogeneity lengths can be measured in three independent
directions. By convention and convenience, these are chosen along thebeam axis (“long”), along the transverse motion of the pions (“out”)
and perpendicular to these two directions (“side”). See text for details.

16

about collective dynamics of the system.
Looking further at the Figure, we also notice that the homogeneity region has a distinct “tilt”– the long axis of its
ellipse makes an angle with respect to the reaction plane. By measuring these “tilts,” we gain geometrical information
about the overall shape of the source when it begins to emit particles. The relevance of this shape information tounderstanding the collision evolution was discussed in Section IV.C.2.
Finally, we know that collective dynamical eﬀects (“flow”) represent a crucial feature which we’d like to study. As
discussed in Section IV.C.2, we can do this by measuring homogeneity lengths as a function of particle momentum. In
fact, by measuring the ways in which the size and shape of the homogeneity region vary with momentum, we extract
details on the magnitude and microscopic nature of the collective flow which dominates the collision evolution.
Here, I have simply sketched out how our technique of measuring geometry can be extended to obtain this moredetailed information, without going through all the math to prove it to you. For those who want more details, pleasesee (12).

Now?

As discussed in Section IV.C, this is an important diagnostic tool to determine (a) whether we ha system in the collision, and (b) the magnitude of the pressure generated in this system (this giv
Equation of State discussed in Section IV.A).
Thus, when one of the very first analyses of RHIC data showed clear evidence of very strong
it generated huge community interest. Elliptic flow at RHIC continues to be studied in ever-incre

A. Elliptic flow

Now that we have discussed the ways in which we measure geometry and some of the physics i
extract from it, I will only very briefly discuss a few of the geometrical results we have obtained at

VI. GEOMETRICAL OBSERVATIONS AT RHIC

about collective dynamics of the system.
Looking further at the Figure, we also notice that the homogeneity region has a distinct “tilt”– tellipse makes an angle with respect to the reaction plane. By measuring these “tilts,” we gain geome
about the overall shape of the source when it begins to emit particles. The relevance of this sha
understanding the collision evolution was discussed in Section IV.C.2.
Finally, we know that collective dynamical eﬀects (“flow”) represent a crucial feature which we’
discussed in Section IV.C.2, we can do this by measuring homogeneity lengths as a function of parti
fact, by measuring the ways in which the size and shape of the homogeneity region vary with mom
details on the magnitude and microscopic nature of the collective flow which dominates the collisio
Here, I have simply sketched out how our technique of measuring geometry can be extended todetailed information, without going through all the math to prove it to you. For those who want msee (12).

FIG. 14 Hydrodynamic prratio of homogeneity lengt
function of energy. Thicksition into QGP during t
thin lines are for no translinestyles and the two pane
assumptions within the mo

At the beginning of the RHIC

Femtoscopy
FIG. 14 Hydrodynamic predictions (4) of theratio of homogeneity lengths Rout /Rside as afunction of energy. Thick lines are for transition into QGP during the collision, while
thin lines are for no transition. The variouslinestyles and the two panels represent various
assumptions within the model.

Figure 1.3: The evolutio⌧ as indicated. Red ind
to convert to hadrons at
the grey region).
H. Masui, KPS, Nov/1/2013!11 /20

oscillations relative to the flow angle Ψ3 flips by π/3 between! Ro has finite
oscillation
exceptevent
ϵ̄3 =0.25 and 0.3,
as a peripheral
resultΨ3 itself
flipping0 by π/3 (see00, in general the source will exhibit flow andFig. 1).

Triangular oscillation
2R2o [fm2]

R2s [fm2]

nisotropies concurrently.
Figure 5 showsrd
BToscillations
radii w.r.t
3o,s
2 -order event
-0.1
-0.1
-0.1
Rµ2 ofplane
larof R
for a sequence
0
100
200
300
0
100
200
300QM2012
0
100
200
300
PHENIX,
2
Npart
Npart
Npart
R
all have the same
triangularflow
anisotropyµ,3Average of radii is set to “10” or “5”for w.r.t Ψ and w.r.t Ψ
To explore this last question a bit further, we
Rµ,02triangut feature varying degrees of spatial
2
2
2
2R
-2R
/ 2R2o,0-2R2l,3Preliminary/ R2l,0PHENIX
returntocompletely
dominated”
2 s,3 / R
2 the
2 o,3 “geometrys,0-2Ro,3 / Rs,02R os,3 / Rs,0
he oscillation
amplitudes,
as well as the mean
1010 (ϵ̄ = 0.1
0.25, v̄3 = 0) and completely“flow anisotropy
dom0.10.1
0 withπ/3 2π/3
oth Rs2 and Ro2 increase monotonically0.1
0.1 
inated” (ϵ̄ = 0, v̄3 = 0.25) sources studied in Figs.
3 and
Au+Au 200GeV 0-10%
y ϵ̄3 . As
Fig.
1
shows,
just
after
ϵ̄
reaches
the
φ
Ψ
π
π
+
π
π
3
5
5
pair
3
4. In0 Fig. 6 we show for 0these extreme models
the200GeV
K⊥ 0
w.r.t
Ψ
Au+Au
the flow angle Ψ3 flips from 0 to π/3. This00dependence of their third-order oscillation amplitudes◦
w.r.t Ψin Fig.
5byasudden
60
phase
shift
rela2
2
π π +π π
00Rs,3and Ro,3. At low K-0.1-0.1-0.1 of the os⊥ , the opposite signs
2
2
f both Rs andFor
φ - ΨR[rad]φ-Ψ[rad] the given-0.1 0-0.1 0
100
200
300
100
200
300
0
100
200
300
o oscillations.
0
100
200
300
0
100
200
300Npart
N
Npart
2
part
N
N
opy
v̄
=
0.25,
as
long
as
ϵ̄
<
0.26,
R
has
a
3
3
part
part
Rout clearlyshows a finite oscillation
w.r.t Ψ3oin most central event
PRL.107.252301
0.0
0.2  0.4
0.6
0.8
1.0 0.0
0.2
0.4
0.6
0.8
1.0
or"Strength
emissionalong
thetriangularflow
plane,
w.r.t Ψ3 is comparable to w.r.t Ψ2
PHENIX Preliminary
4 !a" -2R2 / R2!b"/ R22R 2os,3o,3inexperiment;
onlyforspatialdeformations,0s,0What make this Ro oscillation?
2
2
2
R
R
o,3
s,3
0.1
0.1
e"outward
becomes maximal for emis
Triangular radius
spatial shape?
C. J. Plumberg, C. Shen, U. Heinz,0
irection.
phase of the
sideward"TriangularThe
flow?observed
2
arXiv:1306.1485[nucl-th]R
Au+Au 200GeV$2s,3# vthuscentrald HBTtells usto vonlythatthe measured00
3 is comparable
2 in most
2
Ro,3"Emission
duration?to a source in which triangu$4
tions
correspond
π π +π π
0.0
0.2
0.4
0.6
0.8-0.1 1.0 0.0
0.2
0.4
0.6
0.8
1.0
sotropies dominate over geometric triangular
-0.1

0
100
200
300
0
100
200
300
KT !GeV"KN
T !GeV"Npart
eﬀects that are boosted by superimposed raparthus, while aRdirectshows
measurementof ϵ̄3oscillation
is notclear
with respect to Ψ3outFIG. 6: (Color online) K⊥ -dependence of the third-order ose observed oscillation phase can perhaps becillation amplitudes of Rs2 and Ro2 , for the “geometry domilimits on the ratio ϵ̄3 /v̄3 in theoretical modFinite
R
,
zero
R
out
side
nated” (a) and “flow anisotropy dominated” (b) sources studwever, likely that such limits depend ontheied in Figures 3 and 4.
e model emissionfunction.
‣ could suggest triangular flow is dominated at freeze-out
+ +

3

- -

2
3

-3

-2

-1

0

1

2

-3

-2

-1

0

1

2

+ +

- -

3

n

R2s,3 , R2o,3 !fm 2 "

n

3

+ +

- -

•
•

- whereas triangular source shape is very small at freeze-out‣ Important to study kT dependence of asHBT
H. Masui, KPS, Nov/1/2013!12 /20

Freeze-out eccentricity @ BES
Excitation function for freeze-out eccentricity, εFE895 - PLB 496, 2004 (7.4-29.7%)
CERES - PRC 78, 2008 (10-25%)
STAR (-0.5<y<0.5, 10-30%)
STAR (-1<y<-0.5, 10-30%)
STAR (0.5<y<1, 10-30%)
URQMD
Hybrid[BM]+UrQMD
Hybrid[HG]+UrQMD
2D hydro EoS-Q
2D hydro EoS-H
2D hydro EoS-I

Kt = 0.15-0.6 GeV/c*Model centralities
correspond to data

εF

0.4

0.3

0.2

0.1

0
STAR, ISMD2012

1

102

10

3

sNN

10

to equation of statep• Spatial anisotropy is sensitives for data and models [9] (color online).

Figure 3: Freeze out eccentricity, " f , as a function ofmary

STAR preliminarystNN

FIG. 13 The homogeneity lengths can be measured in three independent
directions. By convention and convenience, these are chosen along thebeam axis (“long”), along the transverse motion of the pions (“out”)
and perpendicular to these two directions (“side”). See text for details.

‣ might be signal for 1 order phase transition• Pion freeze-out eccentricity smoothly decreases as a function of beam energy‣ STAR data don’t show non-monotonic energy dependence

FI
ra
fu
sit
th
lin
as

about collective dynamics of the system.
Looking further at the Figure, we also notice that the homogeneity region
ellipse makes an angle with respect to the reaction plane. By measuring thes
about the overall shape of the source when it begins to emit particles. Th
understanding the collision evolution was discussed in Section IV.C.2.
Finally, we know that collective dynamical eﬀects (“flow”) represent a cru
discussed in Section IV.C.2, we can do this by measuring homogeneity length
fact, by measuring the ways in which the size and shape of the homogeneity
details on the magnitude and microscopic nature of the collective flow whic
Here, I have simply sketched out how our technique of measuring geome
detailed information, without going through all the math to prove it to you.

ummarize, ⇤-⇤ correlation function is presented. Fits to data with di↵erent potential
suggest that ⇤-⇤ interaction is attractive. A negative scattering length gives indication
H. Masui, KPS,
non-existence of bound H-dibaryon. A clear source asymmetry signal is observedin Nov/1/2013!13 /20

Fluctuations
H. Masui, KPS, Nov/1/2013!14 /20

Higher (n>2) order moments• At critical point (with infinite system)‣ susceptibilities and correlation length diverge- both quantities cannot be directly measured• Experimental observables‣ Moment (or cumulant) of conserved quantities: net-baryons, net-

charge, net-strangeness, ...
‣ Moment product (cumulant ratio) ↔ ratio of susceptibility⌦

2 ! = ( N )
3
S =
⇠
! 2
!

2

↵

2

⌦

3

↵

⇠ ⇠ , 3 = ( N ) ⇠ ⇠
4
3
4
2
, K =
⇠
2
2
2

4.5

⌦

, 4 = ( N )

4

↵

2

3 h( N )i ⇠ ⇠ 7- directly related to the susceptibility ratios (Lattice QCD)
M. A. Stephanov,- higher moments (cumulants) have higher sensitivity to correlation length PRL102, 032301 (2009)• Signal = Non-monotonic behavior of moment products(cumulant ratios) vs beam energy

H. Masui, KPS, Nov/1/2013!15 /20

Non-gaussian fluctuations
From Wikipedia• 3rd moment = Skewness S‣ Asymmetry• 4th moment = Kurtosis K‣ Peakedness• Both moments = 0 for gaussian distribution• Critical point induces non-gaussian fluctuations
H. Masui, KPS, Nov/1/2013!16 /20

Net-proton fluctuations

Moment Products: Energy Dependence !
STAR, QM2012

Data•! Deviations
below Poisson !

‣ efficiency
uncorrected*
expectations
are observed
beyondstatistical and systematic errors in
Datacompared
0-5%
most central
collisionsto
for various
κσ2andexpectations
Sσ above 7.7 GeV.

•!

Poisson!‣ Forperipheral collisions, the !
deviations above Poission expectations‣ (Negative-) binomial*
are observed below 19.6 GeV.!
!

!

! UrQMD model show monotonic !
behavior
for the moment products,
No significant
excessin!
which non-CP physics, such as!
compared to Poisson & UrQMD
baryon conservation, hadronic
scattering
are implemented.!
‣ Needeffects,
precision
measurements at•

low energies!
* under investigation (not shown here)

H. Masui, KPS, Nov/1/2013!17 /20

Higher Moments of Net-charge

Net-charge fluctuations

σ

•!in
•!F
• Net-charge fluctuation – related tofreeze-out parameters

Sσ

Bazavov et al, PRL 109 (2012) 192302

• !d

•!A
pre
•!A
!!!l

• Data - efficiency uncorrected *preliminary!
• Data compared to various expectations- Poisson- (Negative-)Binomial *κ• Need precision measurements.
STAR, QM2012•N

PHENIX, CPOD2013

!!!!
•!!H
•!!C
!!!!

* Currently under investigation• No significant excess compared to Poisson, models

8th&Interna1onal&Workshop&on&Cri1cal&Point&and&Onset&of&Deconﬁnem

Aug.
2013 →Future
Trends Workshop,
Beijing
X. Dong ?
≠ 19th,PHENIX
acceptance? efficiency
correction‣ STAR

H. Masui, KPS, Nov/1/2013

18!18 /20

Summary• Multi-particle correlations are powerful tool to understand theunderlying collision dynamics in heavy ion collisions!

• Azimuthal anisotropy‣ Flow in d+Au ? Need centrality dependence‣ Possibility to enhance tip-tip collisions by using v2‣ Hint of turn-off signal by breakdown of NCQ scaling between particles

and anti-particles• Femtoscopy‣ Triangular flow is dominated at freeze-out ?
‣ Smooth energy dependence of final freeze-out eccentricity• Fluctuations‣ Need precision measurements for QCD critical point search

H. Masui, KPS, Nov/1/2013!19 /20

Back up

H. Masui, KPS, Nov/1/2013!20 /20

LargePHYSICAL REVIEW
PRLv2
110,difference
142301 (2013) for baryons
STAR PRL110, 143201 (2013),
PRC88, 014902 (2013)

Mo
duce
the m
0.04
theor
the p
theor
0.02
possi
that t
0
Coulo
(only
0
20
40
60
baryo
sNN (GeV)
out
FIG. 2 (color online). The difference in v2 between particles
obser
Difference of v2 between particles and anti-particles
increase! (see legend) as a(X) and their corresponding antiparticles (X)In
pﬃﬃﬃﬃﬃﬃﬃﬃ
in low energies
function of sNN for 0%–80% central Au þ Au collisions. The"v2 f
Baryonsshow
largermesons function. The
dashed lines
in theplotdifference
are fits withthan
a power-law
if diff
error bars depict the combined statistical and systematic
errors.
H. Masui, KPS, Nov/1/2013!21
a/20fun2

v2(X)-v (X)

0.06

•
•

Au+Au, 0%-80%
η-sub EP

-

+

Ξ -Ξ
p-p
Λ-Λ
K+-K
π+-π-

Disappearance of charge separation
 cos(q + q - 2 s) 

0.002

ALICE, arXiv:1207.0900
0.001

2.76 TeV Pb+Pb

62.4 GeV Au+Au

200 GeV Au+Au

39 GeV Au+Au

27 GeV Au+Au

11.5 GeV Au+Au

7.7 GeV Au+Au

γos

0.0005

Opposite sign0-0.0005

Same sign

γss

-0
0.002
001
0.00151

2

 cos(q + q - 2 s) 

γ = 〈cos(φ1+φ2-2Ψ)〉1

20.00150.001

19.6 GeV Au+Au

0.00050-0.0005-0.001
80

STAR preliminary
70

60

50

40

30

20

10

00

70

% Most Central

60

50

40

30

20

10

% Most Central• Charge separation (γ -γ ) at 200 GeV
os

00

70

60

50

40

30

20

10

0

% Most Centralss‣ chiral magnetic effect ?

• Separation decreases with decreasing beam energies,
disappears at √sNN = 11.5 GeV or less

H. Masui, KPS, Nov/1/2013!22 /20