J/y results from PHENIX

Abhisek Sen, Georgia State Universityfor the PHENIX collaboration

Fluctuations, Correlations and RHIC Low Energy RunsBNL, USA

October 5, 2011

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Probing the medium with Quarkonia

Quarkonium dissociation is suggested as a thermometer for the medium created at heavy ion collisions.

J/ψ suppression in heavy ion collisions due to color screening if QGP is formed was proposed by Matsui & Satz [PLB 178, 416(1986)] which has not been exclusively verified by experiments to date.

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Mocsy & PetreczkyPRL. 99, 211602 (2007) 

P. Petreczky, 1001.5284

PHENIX detector configurations

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RPC1

Central arms:Hadrons, photons, electrons• J/y→ e+e-; y’ → e+e-; c → e+e-;• |η|<0.35• pe > 0.2 GeV/c• Δφ=π(2 arms x π/2)

Forward rapidity arms:Muons• J/y→ μ+μ- ; → μ+μ-

• 1.2<|η|<2.2• pμ > 1 GeV/c• Δφ = 2π

200 GeV Results

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Di-leptons in p+p

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Midrapidity |y|<0.35 Forward Rapidity 1.2 < |y| <2.2

PHENIX has excellent capabilities of measuring different quarkonia states in di-electron and di-muon channels.

J/ψproduction at p+p

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Total J/ψ cross-section : 181 +/- 22 nb

ArXiv: 1105.1966v1

J/y feed down measurement

7ArXiv: 1105.1966v1

c →J/y +

= 9.6 +/- 2.4%

= 32 +/- 9 %

J/ψ suppression in Au+Au 200 GeV

8arXiv: 1103:6269 (accepted to PRC yesterday)

Puzzle:

Suppression is stronger at forward rapidity than mid-rapidity.

Understanding J/ψ suppression in Au+Au

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Enough temperature to melt ψ’ and C according to lattice calculations.

An extreme case :

Total J/ψfeed-down : 42 +/- 9 %

Comparison with other energies

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Adding more to the puzzle

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NA50, 17.2 GeV

No obvious pattern of the suppression with energy density.

PHENIX LOW ENERGY DATASET

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Available Data Sets

Good for J/ψanalysis. Not enough J/ψ statistics.

J/ψfrom Au+Au 62.4 GeV and 39 GeV

In 2010 PHENIX collected 700M (200M) MB events from 62.4 GeV (39 GeV) Au+Au collision.

Total No of J/ψ’s 62 GeV: 1130.4 +/-

172.7(stat) 39 GeV: 169.1 +/-

82.7(stat)

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Accptance Weighted fit: RED : Total fit, BLACK: Double Gaussian components for J/Y , BLUE: Exponential component, GREEN: Low mass peak fit component.

62 GeV

39 GeV

J/ψ Invariant yields in Au+Au collision

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Rapidity 1.2 <|y| <2.2

Energy dependence of J/ψ RCP

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PHENIX doesn’t have a p+p reference at 62 and 39 GeV. Rcp will give us an insight about the suppression level. Suppression is of similar level within uncertainties.

Rapidity 1.2 <|y| <2.2

Quarkonia Suppression Similarity in √s

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Overall suppression of J/ψ is nearly “similar” between RHIC, SPS, & LHC ?

62 GeV 39 GeV

CMS - pT > 6.5

SPS

PHENIX forward

PHENIX y=0

A Recipe for Suppression

The Ingredients:CNM effectsshadowing, gluon saturation, nuclear absorption, initial-state parton energy lossHNM effectsdissociation, regeneration

But what are the proportions? How they depend on energy?Is centrality is a good variable for comparison?

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Few CNM effects in Quarkonia production

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Traditional shadowing from fits to DIS or from coherence models

D

Dcc moversco-

Absorption (or dissociation) of into two D mesons by nucleus or co-movers

ccshadowing

anti-shadowing

R G in

Au

Start by looking at CNM effects using d+Au collisions.

Note: Gluon shadowing affects the underlying charm yield.Absorption reduces the fraction of charm forming bound charmonium.

There are other possible mechanisms that modify quarkonium production.Initial state energy loss and Cronin effect are examples.

J/ψ suppression in d+Au

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(Solid Red curves) A reasonable aggreement with EPS09 nPDF + sbr = 4 mb .

(Dashed green line) CGC calculations can’t reproduce mid-rapidity. (Nucl. Phys. A 770(2006) 40)

PhysRevLett.107.142301

y

What about Rcp ?

EPS09 with assumed linear thickness dependence fails to describe centrality dependence of forward rapidity region.

Geometry integrated EPS09 is in agreement with MB centrality integrated data.

Lets arbitrarily give EPS09 a linear geometry dependence

(Solid Red curves) A reasonable aggreement with EPS09 nPDF + sbr = 4 mb for central collisions but not peripheral.

(Dashed green line) CGC calculations can’t reproduce mid-rapidity. (Nucl. Phys. A 770(2006) 40)

Aud

d+Au Geometry dependence

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0

1( ) ( , )T Tr dz z r

Nuclear geometry via density-weighted longitudinal thickness

Woods-Saxon

• Break-up has exponential dependence.

• EPS09 has unknown dependence.

RdAu with geometry

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The forward rapidity points suggests a quadratic or higher geometry dependence.

For any value of a, we can put a point in the RCP(a) - RdAu(a) plane.

Ellipses are systematic uncertainties.

CNM extrapolation in Au+Au

Projection of EPS09 shadowing and sbr to Au+Au collision in mid-rapidity and forward-rapidity doesn’t reproduce RAA or the ratio between rapidities.

Picture is more complex today with strong cold nuclear matter effects and different hot nuclear suppression.

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Energy dependence of CNMs

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JHEP 0902:014 (2009)

RG for J/ψ production at RHIC A systematic analysis at y~0 using EKS98 + σbreakup showed a clear collision energy dependence of σbreakup.

-2.2 < y < -1.21.2 < y < 2.2 |y| < 0.5

Work in progress

PHENIX Run Plan

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Run Species s Wks 30 cm 10 cm Pol Comments11 p+p 500 10 27 pb-1 50%(L) W program + G

Au+Au 19.6 1.5 13.7M MB evts energy scan

Au+Au 200 8 700 b-1 heavy flavor (VTX)12 p+p 200 5 13.1 pb-1 4.7 pb-1 60%(T) HI ref. + transv. spin

p+p 500 8 100 pb-1 35 pb-1 50%(L) W program + GAu+Au 200 7 800 b-1 Heavy flavor (FVTX/VTX)U+U 200 1.5 0.3 nb-1 explore geometryAu+Au 27 1 5.2 b-1 energy scan

13 p+p 500 10 200 pb-1 74 pb-1 60%(L) W programp+p 200 5 20 pb-1 4.7 pb-1 60%(T) HI ref. + transv. spinCu+Au 200 5 2.4 nb-1 geometryU+U 200 5 0.57 nb-1 geometry

14 p+p 200 10 34 pb-1 12 pb-1 65%(T) HI ref. + transv. spinp+p 62 3 0.6 pb-1 0.2 pb-1 60%(T/L) HI ref. + transv. spin

d+Au 200 8 260 nb-1 150 nb-1 CNMd+Au 62 2 6.5 nb-1 3.8 nb-1 CNM

15 Au+Au 200 10 2.8 nb-1 high bandwidthAu+Au 62 4 0.13 nb-1 HF vs sp+3He 132 5 (T) test run

Summary

Similar J/y suppression at 200, 62 and 39 GeV at Au+Au collision, when looking at centrality dependence.

CNM effects are a large fraction of the observed Au+Au suppression and extrapolation from d+Au to Au+Au is imperative.

Geometry dependence of shadowing is stronger than linear.

CNM effects not same at all energies. Need a consistent study of different nuclear matter effects to understand the suppression.

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BACK-UP

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PHENIX Muon-Arm

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g+g -> J/y

Rapidity 1.2 <|y| <2.2

PHENIX Muon Arm performance

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Dimuon mass acceptanceInput: Flat Mass, Pt, rapidity

J/y acc*eff at 62 GeV Au+Au

Muon Tracker performance at

Run10

Few CNM effects in Quarkonia production

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Traditional shadowing from fits to DIS or from coherence models

high xlow x

D

Dcc moversco-

Absorption (or dissociation) of into two D mesons by nucleus or co-movers

cc

Energy loss of incident gluon shifts effective xF and produces nuclear suppression which increases with xF

R(A/p)R=1 xF

Gluon saturation from non-linear gluon interactions for the high density at small x; amplified in a nucleus.

shadowing

anti-shadowing

R G in

Au

pA

Start by looking at CNM effects using d+Au collisions.