Quarkonia and vector mesons in d+Au collision at forward rapidity in PHENIX

Kwangbok Lee

Korea Universityfor PHENIX collaboration

121 April DIS 2010, Florence, ItalyKwangbok Lee

MotivationⅠ- Quarkonia in A+A

hep-ph/0609197v1 H. Satz

Kwangbok Lee

- Binding of a pair is subject to color screening in QGP.- Melting temperatures depend on their binding radius.- Temperature of QGP can be estimated or another models like regeneration can be tested.

- Each quarkonium has different binding radius.

state J/y cc U1S U2S U3S

mass [GeV] 3.10 3.53 9.46 10.02 10.36DE [GeV] 0.64 0.20 1.10 0.54 0.20radius [fm] 0.25 0.36 0.14 0.28 0.39

Perturbative Vacuum

cc

Color Screening

cc

arXiv:0911.4806

221 April DIS 2010, Florence, Italy

MotivationⅡ- Quarkonia in d+A

R GPb

Q2 = 1.69 GeV2

EPS08

EPS09

nDS

EKS98

HKN07

- Shadowing model <- Gluon densities in nucleus with different parton distribution functions(PDF) Color Glass Condensate(CGC)/Gluon saturation.- Nuclear absorption (Now we are comparing shadowing models to J/y signal)- Initial state parton energy loss- Cronin effect

2. Essential information to understand QGP.

1. Cold nuclear matter effect

low x high x

shadowing

antishadowing

Gluon density in different x

321 April DIS 2010, Florence, ItalyKwangbok Lee

arXiv:0902.4154

4

South North

d Au + -

PHENIX Muon Arm

Kwangbok Lee

The average value of the momentum fraction x2

in the gold nucleus vs. rapidity for √sNN = 200 GeV

<y> ~ -1.7, x2 ~ 0.11Gold going direction

<y> ~ 1.7, x2 ~ 0.0035deuteron going direction

thought to be in shadowing region

21 April DIS 2010, Florence, ItalySouth

Sout

hNorth

Nor

th

Nuclear modification factors

Ncoll : number of binary collisions, 1 in p+p collision.

If there is no nuclear matter effect, RdAu = Rcp = 1If there is suppression, RdAu , Rcp < 1

pp dAu(all centralities)

dAu(0-20%)

dAu(60-88%)

Ncoll 1 7.6 ± 0.4 15.1 ± 1.0 3.2 ± 0.2

521 April DIS 2010, Florence, ItalyKwangbok Lee

J/y RdAu

Shadowing model comparison toRdAu values with EKS PDF and fixed breakup cross sections

With NDSG and fixed breakupcross sections

arXiv:0903.4845(Erratum)

Published RdAu vs. rapidity result

PDF EKS(mb) NDSG(mb)

breakup 2.8 +2.3 -2.1 2.6 +2.2 -2.6621 April DIS 2010, Florence, ItalyKwangbok Lee

Run2003 dAu/Run2005 pp, PRC 79, 059901(E) (2009)

EKSσ = 0 mb

σ = 4 mb

NDSGσ = 0 mb

σ = 4 mb

PHENIX PRELIMINARY

PHENIX PRELIMINARY

J/y Rcp

• Preliminary result with 2008 d+Au data which has ~30 times statistics than 2003 d+Au data.• Can’t fit the data with fixed breakup cross sections.

• Need to understand the suppression of shadowing region.

Rcp vs. rapidity721 April DIS 2010, Florence, ItalyKwangbok Lee

p+p

d+Au

8Kwangbok Lee 21 April DIS 2010, Florence, Italy

High mass distribution

Physical background of Drell Yan, and is estimated (pythia)

Deuteron(d) going, y>0Gold(Au) going, y<0

BR*dσ/dy = 9.6±2.1(stat.)±1.5(syst.)nb, y [-2.2, -1.2]

Upsilon cross sections

9Kwangbok Lee

BR*dσ/dy = 31.1±8.7(stat.)±6.2(syst.)pb, y [1.2, 2.2]

BR*dσ/dy = 28.2±9.4(stat.)±4.8(syst.)pb, y [-2.2, -1.2]

BR*dσ/dy = 6.7±1.7(stat.)±1.5(syst.)nb, y [1.2, 2.2]

• pp cross section is reference to comparison to d+Au collision.• pp cross section vs. rapidity is following the shape of Color Evaporation Model-CTEQ6M(PDF)(scaled down by ~2).• Cross section vs. rapidity of d+Au collision is asymmetric.

21 April DIS 2010, Florence, Italy

RdAu = 0.84±0.34(stat.)±0.20(sys.), y [-2.2, -1.2]

RdAu = 0.53±0.20(stat.)±0.16(sys.), y [1.2, 2.2]

• First Upsilon RdAu measurement at forward rapidity.• Showing suppression at small x region.• Waiting for theoretical comparison.

Upsilon RdAu

1021 April DIS 2010, Florence, ItalyKwangbok Lee

Light Vector Mesons Rcp

• First nuclear modification factor measurement for low mass vector mesons in forward rapidity.• Significant suppression at deuteron going direction.• Stronger suppression for / r w than f and J/Y.

Gold(Au) going, y<0 Deuteron(d) going, y>0

1121 April DIS 2010, Florence, ItalyKwangbok Lee

Prospect for cc

12

cc is a very important particle to calculate the actual feed-down contributions to J/y, to decouple the cold nuclear matter effect.

2008 dAu North arm

Muon Arm1.2<|y|<2.2

Kwangbok Lee 21 April DIS 2010, Florence, Italy

Foreground eventScaled mixed eventSignal(Foreground – Mixed)

Signal fitting with Gaussian and polynomial

MPC3.1<|y|<3.8

Summary• Nuclear modification factors of Upsilon, J/ y and light vector mesons are

shown.

• They show suppression at low x region but, not clearly understood yet.• Recent J/ y Rcp result is not explained well with shadowing model and fixed

breakup cross sections. • New Upsilon RdAu shows suppression in low x region and need to have

theoretical comparison.• Low mass vector meson need to understand its production mechanisms.

• feed down to J/y measurement is underway and important to decouple the cold nuclear matter effect and QGP state.

• In future, PHENIX FVTX/VTX upgrade will reduce more background and make the y’ and even Drell-Yan measurement possible.

1321 April DIS 2010, Florence, ItalyKwangbok Lee