06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 1

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 Tsukuba 2

RHIC 200GeV SPS 17GeVRHIC 62GeV

PHENIXnucl-ex/0611019

S.Kniege, ISMD 2007

jet

p p

Au Au

Jet suppression modification with 2-particle correlation

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 3

3<pTtrig<4GeV/c & 1.0<pT

asso<1.5GeV/c 20-60%STAR

= associate - trigger (rad)

Jet modification and geometry(and v2)

QM08: STAR, PHENIX

QM04: STAR

Mach-cone shape depends on R.P. angle.Mach-cone is a source of of v2

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 4

ASSO.-TRIG. < 0

ASSO.-TRIG. > 0

in-pl.

in-pl.

out-of-pl.

out-of-pl.

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 5

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

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)

(1)(2)

(3)(4)(5)

(6)

(7)(8)

trigger particle

A

SS

O

TR

IG ) < 0

ASSO TRIG ) > 0

ASSO TRIG (rad)

(1)(2)

(3)(4)

Simulation Study

ASSO TRIG (rad)

(5)(6)

(7)(8)

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 6

Simulation

(1)(2)

(3)

(4)

(5)

(6)

(7)(8)(1)

(2)

(3)

(4)

(5)

(6)

(7)(8)

in-plane

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

two-

part

icle

cor

rela

tion

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

ASSO TRIG (rad)

* 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)

in-plane out-of-plane

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 7

Simulation

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

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

(1)(2)

(3)

(4)

(5)

(6)

(7)(8)(1)

(2)

(3)

(4)

(5)

(6)

(7)(8)

in-plane

ASSO TRIG (rad)

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

top : left-right separated trigger w.r.t. R.P.bottom : left-right non-separatedline : average of all (1) - (8)

with experimental E.P. resolution ~0.7

in-plane out-of-plane

flow

-sub

trac

ted

corr

elat

ion

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 8

Simulation

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

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

(1)(2)

(3)

(4)

(5)

(6)

(7)(8)(1)

(2)

(3)

(4)

(5)

(6)

(7)(8)

in-plane

flow

-sub

trac

ted

corr

elat

ion

ASSO TRIG (rad)

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

in-plane out-of-plane

top : left-right separated trigger w.r.t. R.P.bottom : left-right non-separatedline : average of all (1) - (8)

with true R.P. (resolution = 1.0)

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 9

Simulationin-plane out-of-plane

flow

-sub

trac

ted

corr

elat

ion

ASSO TRIG (rad)

no R.P. d

ependence on jet s

hape

(This will b

e a pure non-flow.)

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RHIC 200GeV Au+Au, mid-central collisionsat 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 R.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 gap…

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 11

STAR Preliminary

Rid

ge

Jet

3<pTtrig<4, 1.5<pT

trig<2.0 GeV/c

QM08 STAR

STAR

(rad)

RidgeRidge

“jet”Au+Au, 200 GeV

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

Jet does not depends on itJet reduces v2

(rad)

PYTHIA p+p

away side (in d) of one di-jet can be near side (in d) of another di-jet

06/Feb/2009 High pT Physics, Prague ShinIchi Esumi, Univ. of Tsukuba 12

(rad)

PYTHIA p+ptrigger

near side

away sidey

x

(1) away side of a back-to-back(b-t-b) jet is wider in than in (2) 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.(3) Suppression as well as modification of b-t-b jet would depend on re

lative angle w.r.t. almond geometry, we know this from v2 measurement and believe this is the major source of v2 at high pT .

(4) 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).

(5) 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 .

(6) We subtract BG contribution with this v2 from (5) by maximizing BG contribution assuming zero jet yield at minimum at any d.

(7) If near and away side jets overlap each other, this subtraction underestimates the jet yield and can change the extracted jet shape.

(8) 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).