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Jet correlation (Mach-cone, Ridge) at RHIC
ShinIchi Esumi
Inst. of Physics, Univ. of Tsukuba
Contents
•Jet-Suppression and Modification
•Mach-cone and Ridge
•Identified Particle Correlation
•Correlation w.r.t. Reaction Plane
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Use Jet as a probe of High-Energy and Density Matter
Jet in p+p, d+Au or Peripheral Au+Au Collision as a Base Line
Subtraction of Non-Correlated BG in Central Heavy-Ion Collisions
p
dp++Au

KEK seminar, 5/Nov/2008
Au + Au

Univ. of Tsukuba, ShinIchi Esumi
2
Jet suppression modification
with 2-particle  correlation
jet
p
RHIC 200GeV
Au
p
RHIC 62GeV
Au
SPS 17GeV
PHENIX
nucl-ex/0611019
S.Kniege, ISMD 2007
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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p+p vs Au+Au cent 60-92%
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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p+p vs Au+Au cent 0-20%
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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8 < pT(trig) < 15 GeV/c
STAR, Phys. Rev. Lett. 97 (2006) 162301
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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large BG subtraction
with v2 like flow shape
description of jet shape
with several key words
Same Side
Far Side
double peak region
p region
Near Region
KEK seminar, 5/Nov/2008
Away Region
Shoulder Region
Head Region
Shoulder Region
Univ. of Tsukuba, ShinIchi Esumi
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Phys. Rev. Lett. 97, 052301 (2006)
Leading
hadrons
Medium
PRL 98 232302 (2007)
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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System Size and Beam Energy Dependence of Jet Shape
nucl-ex/0611019
No energy dependence (62 ~ 200GeV)
Rapid change between Npart = 0 ~ 100
Almost no change above Npart > 100
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Transverse Momentum (Trigger, Associate) Dependence of Jet Shape
arXiv:0801.4545
Suppression in both near/away side peak at high pT
Enhancement in near side peak at low pT
Development of away side shoulder at low pT
KEK seminar, 5/Nov/2008
No pT dependence of
shoulder peak position
Univ. of Tsukuba, ShinIchi Esumi
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3-particle correlation “12 vs 13”
d+Au Collisions
Trigger
Asso.2
Asso.2
Asso.1
(1-2)/2
Au+Au Central 0-12%
Cone angle (radians)
No pT dependence, too.
STAR Preliminary
STAR Preliminary
KEK seminar, 5/Nov/2008
(1-2)/2
pT (GeV/c)
Univ. of Tsukuba, ShinIchi Esumi
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3 Particle Correlations in High pT Framework (*)
Hi pT(1)
Polar plot
Same Side
along
azimuth
*
 *
 * =  * _  *
12
13
Away Side
along
radius
*
*
 = 
12
Assoc. pTs (2,3)
Normal Jet
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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High pT(1)
Deflected and Cone Jet Sims
High pT(1)
2-particle Correlations matched
Deflected jet sim
Mach Cone sim
3-Particle di-jet correlations allow a distinction
between different mechanistic scenarios !
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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*=0
*=p
Deflected Jets
Cone like Jets
PHENIX Preliminary
PHENIX Preliminary
Deflected jet simulation
KEK seminar, 5/Nov/2008
Mach Cone simulation
Univ. of Tsukuba, ShinIchi Esumi
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d+Au, 200 GeV
Au+Au, 200 GeV
STAR QM06
“jet”
p+p, peripheral Au+Au
KEK seminar, 5/Nov/2008
central Au+Au
PHENIX QM08
Univ. of Tsukuba, ShinIchi Esumi
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yield,)
STAR QM06
Jet+Ridge ()
Jet ()
Jet)
preliminary
Au+Au 0-10%
“jet
”
Npart
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Centrality Dependence of Ridge and Shoulder Yield and <pT>
QM08 PHENIX
Both ridge and shoulder yields increase linearly with Npart.
Similar (flat) centrality dependence on inverse slope parameter for both ridge and shoulder.
Jet (p+p) like pT shape is harder than ridge, ridge is harder than shoulder, shoulder is similar to inclusive.
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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TInclusive ~
< TShoulder ~< TRidge < TJet
STAR Preliminary
QM06
inclusive
ridge
jet
QM08
Both ridge and shoulder <pT> are almost independent with centrality and trigger pT selections.
It’s just like a bulk matter… suspicious on BG(bulk) subtraction… but this is what we see…
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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J of Phys: Conf
27 (2005) 98
M. Daugherity, QM08
2-particle correlation
transverse correlations
without high pT trigger selection
axial correlations
200GeV p+p
pT (Gev/c)
yt2
4
3
2
1
0.5
φΔ
ηΔ
yt ~ ln(pt)
soft component
yt1
hard component
These structures
define minijet
correlations
φΔ
ηΔ
Longitudinal Fragmentation
(“strings”) 1D Gaussian, US pairs
HBT peak at origin, LS pairs
KEK seminar, 5/Nov/2008
φΔ
Minijets 2D Gaussian at origin,
away-side peak actually cos(φΔ)
Univ. of Tsukuba, ShinIchi Esumi
ηΔ
19
M. Daugherity, QM08
Δφ
longitudinal fragmentation
1D gaussian
HBT, res., e+e2D exponential
Δη
Minijet Peak
2D gaussian
Away-side
-cos(φ)
1.2M minbias 200 GeV Au+Au events
Included all tracks with pT > 0.15 GeV/c, | | < 1, full 
Elliptic flow
cos(2φΔ)
STAR Preliminary
84-93%
75-84%
65-75%
55-65%
46-55%
28-38%
19-28%
9-19%
5-9%
0-5%
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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data - fit (except same-side peak)
QM08 STAR
83-94%
55-65%
Shape changes little from
peripheral to the transition
46-55%
Large change
within ~10%
centrality
0-5%
Smaller change from
transition to most central
Peak η Width
Peak φ Width
STAR Preliminary
200 GeV
62 GeV
STAR Preliminary
STAR Preliminary
binary scaling assumption
in Kharzeev and Nardi model
KEK seminar, 5/Nov/2008
Extracted 2-D near-side Gaussian
parameters are shown. The strong 
width change vs centrality should
have a relation to the ridge
formation.
Peak Amplitude
longitudinal (density
correlation length
HIJING 1.382 default
200 GeV, quench off
Centrality
Univ. of Tsukuba, ShinIchi Esumi
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Hadron trigger with identified
associate Baryon/Meson
arXiv:0712.3033
Near/Away-side B/M ratio increases in central
Away-side B/M ratios approach inclusive values
Incompatible with in-vacuum fragmentation
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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C. Suarez et al, QM08
Au+Au: 2 < pTtrig < 3 GeV/c
Cu+Cu: 3 < pTtrig < 6 GeV/c
pTtrig > 4.0 GeV/c
2.0 < pTAssoc < pTtrig
Baryon/meson ratio in ridge close to inclusive, in jet close to p+p
M. Lamont et al, QM05 J. Bielcikova et al, WWND07, C. Nattrass et al, QM08
p+p / p++p-
Associated baryon/meson ratios
Different production mechanisms for ridge and jet?
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Ridge event-by-event: 3-particle -
trigger
2
1
Idea: Distinguish
and
Ridge particles on either side:
uniform -
KEK seminar, 5/Nov/2008
Both ridge particles on one side:
diagonal structure
1 jet-like associated, 1 ridge-like:
Bands along axes
Univ. of Tsukuba, ShinIchi Esumi
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P. Netrakanti et al, QM08
- results
Radial distribution
dAu
dAu
dAu
3<pTTrig<10 GeV/c
1<pTAsso<3 GeV/c
STAR Preliminary
STAR Preliminary
STAR Preliminary
STAR Preliminary
AuAu
0-12%
AuAu
AuAu
0-12%
0-12%
Shaded : sys. error.
Line : v2 uncer.
Note : 2x1 b.g.
subtracted
STAR Preliminary
- structure: central peak + uniform
No substructure in ridge: no gluon fragments?
Note absence of excess along axes: no jet+ridge events?
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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|ηtrig|<1
3<pTtrig<10 GeV/c
2.7<|ηassoc|<3.9
0.2<pTassoc< 2 GeV/c
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Trigger: MTPC: 3<pTtrig<4 GeV/c,
Associated: FTPC: 0.2<pTassoc< 2 GeV/c, MTPC: 0.2<pTassoc< 3 GeV/c
KEK seminar, 5/Nov/2008
AuAu 0-10%
AuAu 0-5%
AuAu 60-80%
dAu MB
pp MB
Univ. of Tsukuba, ShinIchi Esumi
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Identified p0 trigger with associate hadron
QM08 PHENIX
7-9 (X) 1-2
0-20%
7-9 (X) 4-5
0-20%
PHENIX preliminary
7-9 (X) 4-5
60-90%
7-9 (X) 4-5
40-60%
7-9 (X) 4-5
20-40%
7-9 (X) 6-8
40-60%
Width does not change with centrality
similar to charged hadron triggered case.
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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QM08 PHENIX
Direct  trigger with associate hadron
Per-Trigger Yield (A.U.)
1/Ntrig dN/d (A.U.)
p+p: Consistent with trigger photon
carrying the full jet energy, away side
jets are similar between p0 and  triggers.
Run 6 p+p @ 200 GeV
pT, photon GeV
Run 7 Au+Au @ 200 GeV, cent=0~20%, preliminary
0
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
Need more studies and
statistics for Au+Au case.
Run 4/5 p+p/Au+Au @ 200 GeV
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Jet modification
and geometry
(and v2)
QM04: STAR
QM08: STAR, PHENIX
STAR
3<pTtrig<4GeV/c & 1.0<pTasso<1.5GeV/c 20-60%
Mach-cone shape depends on R.P. angle.
Mach-cone is a source of of v2
 = associate - trigger (rad)
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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v2
0
Shoulder (cone)
Head (p)
Ridge
Ridge
0
v2
Jet
Shoulder (cone)
Au+Au, 200 GeV
Ridge/Cone and
geometry (v2)
“jet”
STAR
p
Ridge shape depends on R.P. angle.
Ridge is a source of of v2
Jet does not depends on it
Jet reduces v2
QM08 STAR
Ridge
3<pTtrig<4, 1.5<pTtrig<2.0 GeV/c
STAR Preliminary
Jet
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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trigger

y
x
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
away side
near side
away side of a back-to-back(b-t-b) jet is wider in  than in 
If there are two parallel b-t-b jets, away side of one b-t-b jet can be
near side of the another b-t-b jet.
Suppression as well as modification of b-t-b jet would depend on
relative angle w.r.t. almond geometry, we know this from v2
measurement and believe this is the major source of v2 at high pT .
Therefore, there should be inter b-t-b jets correlation give by the
geometry from (3), this could make near side ridge like effect,
especially if the effect (3) has shaper dependence than v2(=cos2x).
We always measure inclusive v2, which includes the effect (3).
Therefore any modification which could generates the elliptic
anisotropy would be included in the measured v2 .
We subtract BG contribution with this v2 from (5) by maximizing
BG contribution assuming zero jet yield at minimum at any d.
If near and away side jets overlap each other, this subtraction
underestimates the jet yield and can change the extracted jet shape.
If you extract angular dependence of jet w.r.t. R.P., the results will
easily be affected by the choice of v2 from (5).
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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p
asso.
: 0.7-1.7GeV/c
AMPT 200GeV Au+Au → charged hadrons (|y|<2.0) pTtrig. : 1.7-4GeV/c
T
1/Ntrig. dNasso./d|trig.-asso.|
string-melting 10mb
string-melting 3mb
default AMPT 3mb
b = 12 fm ~
b = 8~12 fm
b = 4~8 fm
b = 0~4 fm
|trig.-asso.| (rad)
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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p
asso.
: 0.7-1.7GeV/c
AMPT 200GeV Au+Au → charged hadrons (|y|<2.0) pTtrig. : 1.7-4GeV/c
T
1/Ntrig. dNasso./d|trig.-asso.|
trigger at in-plane
average
trigger at out-of-plane
b = 12 fm ~
b = 8~12 fm
b = 4~8 fm
b = 0~4 fm
|trig.-asso.| (rad)
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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In order to study the jet modification (mach-cone, ridge)
and it’s relation with almond geometry in more detail…
y
(1)
y
associate particle direction at
same || w.r.t. red dashed line
but with different arrow length
-p0p
(4)
(3)
(2)
(3)
>0
<0
>0
x(R.P.)
(2)
<0
(2)
Trigger
particle
(4)
(1)
associate particle direction at
same || w.r.t. trigger particle
but with different arrow length
KEK seminar, 5/Nov/2008
x(R.P.)
Trigger
particle
ASSO.-TRIG.
with and without R.P. aligned event mixing
Univ. of Tsukuba, ShinIchi Esumi
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AMPT 200GeV Au+Au
default option
(1)
(2)
(3)
(4)
melting-on
(all)
(1)
0~9%
0~9%
9~19%
9~19%
19~39%
19~39%
39~100%
39~100%
KEK seminar, 5/Nov/2008
(2)
(3)
(4)
Univ. of Tsukuba, ShinIchi Esumi
(all)
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KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Summary and Conclusion
・2- and 3- particle correlation and transverse momentum dependence
of jet-modification tells us that it is likely a mach-cone.
・Mach-cone and ridge are almost as soft as inclusive particles.
・Identified particle (baryon, meson, p0, ) correlation measurements.
・Mach-cone and ridge w.r.t. reaction plane angle tells us that this is
a part of v2
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Extra and Back-up Slides
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Identified Baryon/Meson trigger
with associate hadron
PRC71 051902
2.4<pTTrig<4 GeV/c 1.7< pTAsso<2.5 GeV/c
KEK seminar, 5/Nov/2008
Enhanced near-side yield can not be
explained by soft process like thermal
recombination alone.
Univ. of Tsukuba, ShinIchi Esumi
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ave (1)~(8)
(8)
(7)
(6)
(5)
R.P.
(4)
Pure Flow Simulation
with R.P. aligned
event mixing
without R.P. aligned event mixing
with trigger angle selection w.r.t. R.P.
with/without R.P. aligned event mixing
(3)
(2)
(1)
ave (1),(8)
ave (2),(7)
ave (3),(6)
ave (4),(5)
(1)
(8)
(2)
(7)
(3)
(6)
(4)
(5)
(1)
(8)
(2)
(7)
(3)
(6)
(4)
(5)
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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Medium effects w/o subtraction?
Inclusive Au+Au
Au+Au vs. Cent @ p/4
Au+Au vs. RP
• Inclusive correlation Au+Au – Example: 0-5%
– Modest flow in this bin
– Background subtraction can only make effect more pronounced
• Choose a trigger orientation with minimal impact from modulated
background
– 4th bin: ~ p/4 (grey circles)
• Example: Au+Au in 4th RP bin, several centralities
– “mach cone”(?) effect clear without any subtraction
– Need to focus on source of shoulder!
KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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KEK seminar, 5/Nov/2008
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KEK seminar, 5/Nov/2008
Univ. of Tsukuba, ShinIchi Esumi
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