Flow and non-flow in jet correlation
ShinIchi Esumi (Univ. of Tsukuba)
Jiangyong Jia (Stony Brook Univ.)flow: any-correlation with R.P.
non-flow : random w.r.t. R.P.
Jet : If it’s correlated with R.P. ---> flow (high pT v2 > 0) and non-flow
If it’s not correlated with R.P. ---> pure non-flow (B.G. for true v2)(1) “non-flow” effect modifies the measured v2, when they give any
correlations between R.P. detector and v2 detector.
(2) If medium responses (mach-cone, ridge) are related with jet, they
will also be a part of “flow” or “non-flow” according to jet.
(3) Inclusive v2 should contain all of them (jet, mach-cone, ridge),“non-flow” should always reduce the inclusive (true) v2, while“flow” of (jet, mach-cone, ridge) can enhance the (true) v2.
(4) Recent results tell “medium responses” do change its shape andyield as a function of relative angle w.r.t. R.P.
Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

1

QM04: STAR

QM08: STAR, PHENIX

STAR

3<pT trig<4GeV/c & 1.0<pTasso<1.5GeV/c 20-60%

Δφ = φassociate - φtrigger (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba2

Understanding of Mach-cone shape of (pTAsso=1~2GeV/c)with trigger angle selected 2-particle correlration (pTTrig=2~4GeV/c)

out-of-pl.
in-pl.

φASSO.-φTRIG. < 0

φASSO.-φTRIG. > 0in-pl.
out-of-pl.

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

3es id d ir erarn e ig g e(trm a c h -c one( s h o u lde r r e g ion)
φASS -φO TRIG >0id e io n )say egaw ad r(h eoc tin)

φASSO-φTRIG<0mach-cone(shoulder region)
φASSO-φTRIG<0−πCathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

0
φASSO − φTRIG

ShinIchi Esumi, Univ. of Tsukuba

π4triggerparticle(φASSO − φTRIG ) > 0(2)(7)(6)− φ TRI(3)(8). (3)ere
ep on h (2)(7)
ah icati by lso(1)(8)
sfn
jet modie give ould a theon ed d b is c of(6)(φ ASSO(1)

Simulation Study
(5)

(4)

um oul . Th tude ne.
sosc w) ni
adn
(5)
h(4)
ge
e the hic l flo ma ragd
(6)n ince on, w radia the ave(3)
ep . S issi of and ight
(7)(2)
ed ow em ence ield left/r
(8)
(1)
.
e (rad)P φnASSO-fl p−laφnTRIGnd ive y om.
e
R no -of- dep elat nt fr
g e out al e r erenshape(1) = f1(x)o ur (4)an muth n th diffrt(5)p n th azi(3) g o beshape(2) = f2(x)(6)
san(shape(3) = f3(x) ery
sio ion ndi (2)also(7)
esietbsphmv
shape(4) = f4(x)(8)
e pan deig (1)Teemx
shape(5) =mf5(x) =NfO
lan tic e to v 2 evel4(-x)
pun- llip ion M ls = f6w(x)ill =efr3i(-x)
shape(6)
se ut
AfyA
Ybei
shape(7) i=s f7(x)=f(-x)
brZr
pr2 nt n.
shape(8)Thw=afy8s(x)etr=y of1g(-x)
co atioal om tron difics width)
o3 x (peak, leftgeand arightme+ 2 x relative heightb a=pe11 parshφASSO − φTRIG (rad)
(4)

(5)

G)<ce0Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

5input jet shape

Simulation
Input jet + flow
Input parameters(1) Jet shape (11x4)(2) v2,4Trig(soft)
Asso(3) v2,4(soft)(4) v2,4Jet(hard)
PTY(5) v2,4(hard)(6) nTrig / eve (soft)(7) nAsso / eve (soft)(8) nJet / eve (hard)(9) nPTY / jet (hard)in-plane

Output parameters(a) v2,4Trig(incl)
Asso(b) v2,4(incl)(c) nTrig / eve (incl)(d) nAsso / eve (incl)(e) hard/soft frac.
(true frac.)(zyam frac.)

out-of-plane

φAsso − ΦR.P. (trigger angle φTrig selection w.r.t. R.P.,
where, φTrig gives the sign of 2nd order ΦR.P. )Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

6

Simulation

before subtraction

random R.P. mixing (total flow + jet)
1.4

in-planeaveraged

1.0

(1)

(7)

(3)

(6)

(4)

(5)

(5)

(4)

(6)

(3)

(7)

(2)
(8)

1.1

φASSO − φTRIG (rad)

(8)

(2)

before subtraction

out-of-plane(1)

in-plane

2-particle correlation : before subtractionaligned R.P. mixing (reduced flow + jet)in-planeout-of-planeaveraged

1.0
φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

7

Simulation

after subtraction

random R.P. mixing (total flow subtracted jet)in-plane

0.1

averaged

0.0
(1)

(7)

(3)

(6)

(4)

(5)

(5)

(4)

(6)

(3)

(7)

(2)
(8)

0.1

φASSO − φTRIG (rad)

(8)

(2)

after subtraction

out-of-plane(1)

in-plane

2-particle correlation : after subtractionaligned R.P. mixing (reduced flow subtracted jet)in-planeout-of-plane

averaged

0.0
φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

8comparison between input and output

out-of-plane

input

in-plane

Simulation

outputoutputperfect R.P. resolution (σres~1)

experimental R.P. resolution (σres~0.7)

φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

9Simulation

effect of the experimental resolution
σres~1σres~0.9

σres~0.7

σres~0.5

no R.P. bias from jet-correlation

φASSO − φTRIG (rad)R.P. biased by jet-correlation

φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

10

Simulation

flow-subtracted correlation

in-planeout-of-plane,
do e.
og ap
yer t shv
s jee.
ise oncaps
ia ehhts ncint
yje denlotu en
tlypcin ep
ferfe
d w. s po.
on R.P -flo workitc on et)uortn e n w+jss
on re i pur l (floce e a dereth be t mohT en ill en
wh is w mpon
Th o coTw

φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

11

Jiangyong Jia

Simulation
Bin 5

akpearNe

1
Mach cone

Eloss depending onangle w.r.t. R.P. fornear peak andMach cone 1/2

kT smearing included,
modified mach-cone byabsorption according toEloss. The asymmetry isnow flipped.

Bin 0e2ncohc
MaThe multiplicities in these regions
are assumed to be proportional tothe path length (a la energy loss).

φASSO − φTRIG (rad)Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

Note: original jets are generated
according to Ncoll profile

ShinIchi Esumi, Univ. of Tsukuba

12

RHIC 200GeV Au+Au, mid-central collisions
at mid-pT region (1-4 GeV/c) with v2 = 0.1 ~ 0.2* Significant semi-hard (mini-jet) fraction
relative to soft-thermal contribution~ several*10%* Significant v2 effect from the semi-hard component
relative to soft-thermal particle v2~ several*10%* Significant smearing on jet shape even with σR.P.~ 0.7
But it’s not really because of poor accuracy of E.P. angle,
it’s more because mini-jets push up the inclusive v2
which is subtracted.
* RHIC data analysis is in progress…
* E.P. can also be biased by correlated pair even with large η gap…

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

13

Au+Au, 200 GeV“jet”IAPY THp+pSTARegdRi
Δφ(rad)Δη
QM08 STARΔη
away side (in dφ) of one
di-jet can be near side(in dφ) of another di-jetRidge

3<pTtrig<4, 1.5<pTtrig<2.0 GeV/c)Δφ(radSTAR Preliminary

Jet

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

14

trigger
PY THyΔφx

(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)

IA p + p

away sidenear side

away side of a back-to-back(b-t-b) jet is wider in η than in φIf there are two parallel b-t-b jets, away side of one b-t-b jet can benear 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 thegeometry from (3), this could make near side ridge like effect,
especially if the effect (3) has shaper dependence than vn(=cosNx).
We always measure inclusive v2,4, which includes the effect (3).
Therefore any modification which could generates the elliptic (orharmonic) anisotropy would be included in the measured v2,4 .
We subtract BG contribution with this v2,4 from (5) by maximizing
BG contribution assuming zero jet yield at minimum at any dφ.
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 v2,4 from (5).

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNLΔη)Δφ(radShinIchi Esumi, Univ. of Tsukuba

15

Back-up slides

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

16

id e io n )say egaw ad r(h eφASSO-φTRIG<0id e ir es
ar r dn e ig g e(troc tin)−πCathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

0φASSO − φTRIG

ShinIchi Esumi, Univ. of Tsukubaπ17

mixed event flow-subtraction
with perfect resolution

mixed event flow-subtraction
with experimental resolution

Simulation
no flow-subtraction

φAsso − ΦR.P. (trigger angle φTrig selection w.r.t. R.P.,
where, φTrig gives the sign of 2nd order ΦR.P. )Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

18

R.P. resolution = 1
in-planeout-of-plane

averaged

left/right averaged

after subtraction

before subtraction

Simulation

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNLShinIchi Esumi, Univ. of Tsukuba

19

R.P. resolution ~ 0.75
in-planeout-of-plane

averaged

left/right averaged

after subtraction

before subtraction

Simulation

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

20

R.P. biased by jet-correlation
in-planeout-of-plane

averaged

left/right averaged

after subtraction

before subtraction

Simulation

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

21

R.P. biased by jet-correlation (random r.p. mixing)
in-planeout-of-plane

averaged

left/right averaged

after subtraction

before subtraction

Simulation

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

22

σres~0.5

σres~0.7

σres~0.9

σres~1

Simulation without R.P. bias

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

23

σres~0.5

σres~0.7

σres~0.9

σres~1

Simulation with R.P. biased by jet-correlation

Cathie-Riken workshop on Jet-Correlarion, 26/Feb/2009, BNL

ShinIchi Esumi, Univ. of Tsukuba

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