Interplay between jet and v2
ShinIchi Esumi
Inst. of Physics, Univ. of Tsukuba
measurements and simulations

06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba1Jet suppression modification
with 2-particle Δφ correlation

jetp

RHIC 200GeVAup

RHIC 62GeVAu

SPS 17GeVPHENIX
nucl-ex/0611019

S.Kniege, ISMD 2007

06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba2Jet modificationand geometry(and v2)

QM04: STAR

QM08: STAR, PHENIX

STAR

3<pT trig<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

Δφ = φassociate - φtrigger (rad)06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

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out-of-pl.
in-pl.

φASSO.-φTRIG. < 0

φASSO.-φTRIG. > 0in-pl.
out-of-pl.

06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

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Simulation Studytrigger
particle(φASSO − φTRIG ) > 0(5)

(4)

(6)
(8)

(2)

(7)

(4)

(5)

(5)

(4)

(6)

(3)

(1)

G(6)

(2)

(8)

− φ TRI(3)(7)(φ ASSO(1)(3))<0

(7)

(2)
(8)

(1)

shape(1) = f1(x)shape(2) = f2(x)shape(3) = f3(x)shape(4) = f4(x)shape(5) = f5(x) = f4(-x)
shape(6) = f6(x) = f3(-x)
shape(7) = f7(x) = f2(-x)
shape(8) = f8(x) = f1(-x)φASSO − φTRIG (rad)

(5)

(4)

(6)

(3)
(7)

(2)
(8)

(1)

φASSO − φTRIG (rad)06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

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(1)

(8)(2)

(7)

(3)

(6)

(4)

(5)

(5)

(4)

(6)

(3)
(7)

two-particle correlation(5)

in-plane

(2)
(8)

(1)

(4)

Simulation

trigger angle selection
among (1) - (8) regions

(6)

(3)

* two different ways of mixing(top: r.p. random, bottom: r.p. aligned)* flow subtraction(two components flow+jet model,
with inclusive flow measurement,with zyam-like normalization)(7)

in-plane

(2)

(8)

(1)

out-of-plane

φASSO − φTRIG (rad)06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

6(1)

(8)

(2)

(7)

(3)

(6)

(4)

(5)

(5)

(4)

(6)

(3)
(7)

top : left-right separated trigger w.r.t. R.P.
bottom : left-right non-separated
line : average of all (1) - (8)with experimental E.P. resolution ~0.7

(1)(4) (5)flow-subtracted correlation

in-plane(2)(8)

Simulation

trigger angle selection
among (1) - (8) regions(3) (6)(2) (7)in-plane(4) + (5)(1) (8)out-of-plane(3) + (6)(2) + (7)(1) + (8)φASSO − φTRIG (rad)06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

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(1)

(8)

(2)

(7)

(3)

(6)

(4)

(5)

(5)

(4)

(6)

(3)
(7)

top : left-right separated trigger w.r.t. R.P.
bottom : left-right non-separated
line : average of all (1) - (8)with true R.P. (resolution = 1.0)

(1)(4) (5)flow-subtracted correlation

in-plane(2)(8)

Simulation

trigger angle selection
among (1) - (8) regions(3) (6)(2) (7)in-plane(4) + (5)(1) (8)out-of-plane(3) + (6)(2) + (7)(1) + (8)φASSO − φTRIG (rad)06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

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Simulation

flow-subtracted correlation

in-planeout-of-planeepahsjet .)n woolefc nne nodn ureep ped ea.
P ll b.
R wion his(T06/Feb/2009 High pT Physics, Prague

φASSO − φTRIG (rad)ShinIchi Esumi, Univ. of Tsukuba

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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…

06/Feb/2009 High pT Physics, Prague

ShinIchi Esumi, Univ. of Tsukuba

10Au+Au, 200 GeV“jet”IAPY TH

p+pSTARegdRi
Δφ(rad)Δη
QM08 STARΔη
away side (in dφ) of one
di-jet can be near side(in dφ) of another di-jet)Δφ(rad06/Feb/2009 High pT Physics, Prague

STAR Preliminary

Jet does not depends on it
Jet reduces v2

Jet

Ridge shape depends on R.P. angle.
Ridge is a source of of v2

Ridge

3<pTtrig<4, 1.5<pTtrig<2.0 GeV/cShinIchi Esumi, Univ. of Tsukuba

11trigger
IAPY THyΔφx

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

p+p

away side

near side

away side of a back-to-back(b-t-b) jet is wider in η than in φ
If 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 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 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 from (5).

06/Feb/2009 High pT Physics, PragueΔη)Δφ(radShinIchi Esumi, Univ. of Tsukuba

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