Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 HEP2012@Chile 1

Results on deuteron – gold collision at forward rapidity in PHENIX

IhnJea Choi

(UIUC)

For the PHENIX collaboration

01/04/2012

1/4/12 HEP2012@Chile 1

2

Outline

• d+Au collision– Nuclear Modification Factor– Competing models– CGC, Shadowing, Energy Loss, Absorption

• Experiment– RHIC– RHIC luminosity, PHENIX experiment– MPC ( Muon Piston Calorimeter in PHENIX )

• Hadron RdA , RCP results at different rapidity ranges– Hadron and decay muon – Single electron and single muon– J/ψ, Υ– Light vector meson (ϕ, ρ, ω)

• Di-hadron azimuthal angle correlation results– CY, IdA, JdA

– Mid-forward rapidity correlation– Forward-forward rapidity correlation

• Summary1/4/12 HEP2012@Chile

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d+A Collision

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DeutronParton x_d

AuParton x_Au

DeutronParton x_d

AuParton x_Au

Forward rapidity(Deutron going direction)x_d > x_Au (Low x in Au)

Backward rapidity(Au going direction)x_Au > x_d

RHIC experiments have made an amazing array of measurements in d+Au to understand cold nuclear matter

• Initial state effects vital to interpreting results from heavy ion collisions• Are effects at forward rapidity due to gluon saturation effects (have we

reached a regime of QCD where non-linear effects are important)?

Why hadron production suppressed at forward rapidity !

p0 meson

PHENIX |h| < 0.35

RdA

RdA ~ 1 at mid rapidity

PRL 98 (2007), 172302

STAR, BRAHMS Forward hPRL 97 (2006), 152302

Nuclear Modification factor Cold Nuclear Matter(CNM) effect

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Compelling theory models to explain this suppression at forward rapidity.

• Gluon saturation(or CGC)• Nuclear shadowing/ E_loss• Parton recombination• Multi Parton Interaction (MPI)• Momentum imbalance (recent paper)• etc.

STAR BRAHMS results show RdA < 1

As y, energy grows

Color Glass Condensate & Effect

Kharzeev, Kovchegov, and Tuchin, hep-ph/0307037

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Phase diagram of QCD evolution

RpA suppressed at all values of pT as rapidity / energy grows.


Gluon density saturates for large denisites at small x

Mechanism for gluon saturation

Y is related to rapidity of produced hadron

Nuclear Shadowing / Energy Loss / Absorption

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

R(A/p)

R=1 xF

pA

D

Dccmoversco-

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

cc


Shadowing can arise from coherence - Small-x wavefunction spans large longitudinal distances

λ ~ 1/pparton ~ 1/xi.e. the probe interacts with multiple target nucleons coherently

STAR

RHIC

Completed as of 2006

Completed as of 2006

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Run3 d+Au 2.74 nb-1 MB triggered

Run8 d+Au 85 nb-1 MB triggered


RHIC Luminosity

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PHENIX Detector

Muon Arms 1.2 < | η | < 2.4• Heavy Flavor muons• J/Psi• Charged hadrons

Central Arms | η | < 0.35• Charged hadrons• Neutral pions / η-mesons• Heavy Flavor electrons• Direct Photon• J/Psi

Muon Piston Calorimeter (MPC) 3.1 < | η | < 3.8• Neutral pions / η-mesons


Installed2005-7

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PHENIX Muon Piston Calorimeter (MPC)Technology ALICE(PHOS)

PbWO4 avalanche photo diode readout

2.20 x 2.2 x 18 cm3 crystals

Acceptance:

3.1 < η < 3.9, 0 < φ < 2π -3.7 < η < -3.1, 0 < φ < 2π

Both detectors built, installed 2005-2007Usable for 2008 d+Au run.

MPC

p0gg

Merged p0gg


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Single hadron results

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Phys. Rev. Lett. 94, 082302 (2005)

•Forward rapidity suppression •No backward rapidity suppression (slightly enhanced)

• Consistent result with BRAHMS results ( η = 2.2 )

Punch Through Hadron & Hadron Decay Muon RCP

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Mostly π+-,Κ+- and their decay into μ+-

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Heavy quarks RdAu

y = 1.6

Single muons from open charm & beauty:• at forward rapidity suppressed • at backward rapidity enhanced

y = -1.6

Forward/Backward rapiditySingle muon

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CNM effects in J/ψ production

Reasonable agreement with EPS09 nPDF + br=4 mb for central collisions but not peripheral

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

PHENIX arXiv:1010.1246v1


Gluon saturation model is good agreement with data at forward rapidity.

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Y(1S + 2S + 3S) RdA

RdAu = 0.84±0.34(stat.)±0.20(sys.), backward rapidityRdAu = 0.53±0.20(stat.)±0.16(sys.), forward rapidity

• Shows suppression at forward rapidity

STAR Preliminary

PHENIX Preliminary

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Y access different low x range to J/Ψ : Y(x~0.01), J/ψ (x ~ 0.003)

Light vector meson RCP

Comparing Nuclear Modification Factor RCP for ϕ, ρ, ω.

forward rapidityBackward rapidity

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• Significant suppression in forward rapidity• Stronger suppression for /r w than f and J/Y ( Due to lighter quark content, and/or different production mechanisms? )

Forward π0 results for RdA

Suppression increase with increasing rapidity and centrality

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PHENIX MPC

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Forward π0 RdA, Model Comparison


PHENIX MPCShadowing Model overperdicted RdA of central collision data

STAR forward RdA vs. Cronin + Shadowing + E_loss Model good agreement with data

R. B. Neufeld, I. Vitev, and B-W Zhang arXiv:1010.3708

http://arxiv.org/abs/1010.3708v1

Di-hadron correlation

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Accessing Low-x with Di-Hadrons

Guzey, Strikman, Vogelsang, PL B603, 173

Di-Hadrons from Di-Jets Narrow x-rangeSmaller mean x, Constrain x-range !

Single Hadrons

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•However, x covered by single inclusive measurement is over wide range

• Includes shadowing, anti-shadowing, (EMC effect)

Measure Df of all particle pairs trigger particle (usually leading pT) associate particle (lower pT)

trigger

associate

Df

Beam viewor transverse plane

p+p, d+Au di-hadron correlations are similar at mid rapidity

Dh=0 is similar for d+Au (closed) and p+p (open)

S.S Adler et al, Phys. Rev. C 73:054903,2006.

Away-side

Near-side Df

Nearside peak

Df

Awayside Peak

Beam View

Di-hadron azimuthal angle correlation

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Df

CORRELATED NpairCY ( Conditional Yield ) Number of particle pairs per

trigger particle after corrections for efficiencies, combinatoric background, and subtracting off pedestal.

Di-Hadron pair Nuclear Modification factor

pppairpp

dApairdA

colldA NJ

/

/1

ppsglpp

dAsgldA

colldA NR

/

/1

CY / IdA / JdA

Trigger comparison of d+Au jet associated

counts relative to pp

d

dN

NN

NCY

assoc

trigassoctrig

pair 1

Single hadron Nuclear Modification Factor

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J. L. Albacete and C. Marquet, PRL105 (2010) 162301

Di-hadron, CGC signature

• D. Kharzeev, E. Levin, and L. McLerran Nucl. Phys. A748 (2005) 627–640

• Mid-forward di-hadron correlation• Strength of correlation -> CGC phase or still in pQCD• Expected large suppression in dAu than pp• Expected angle broadening of away side peak• Later, not reached low enough low x to see CGC effect

• J.L Albacete and C.Marquet, PRL105 (2010)

• Fwd-Fwd di-hadron correlation

• Access lower x region than mid-forward cor.

• CGC predicts significant b-dependence to

suppression expected

• Width broadening expected at away side peak• High pt of jet balanced by many gluons, Monojet

Fwd di-hadron correlation measurements provide a good testing of CGC theory model

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No significant broadening mid-forward rapidity azimuthal correlations (FMS-BEMC/FMS-TPC) Significant broadening for forward di-pion correlations (FMS-FMS)

Strong suppression of away side peak for central forward-forward correlationwith CGC prediction

Di-hadron azimuthal correlation STAR

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arXiv:1008.3989v1

Multiple soft scatterings de-correlate the away side peak

dynamical shadowing, Energy Loss, Cronin

Dihadron, Shadowing

•Di-Hadron Correlations allow one to select out the di-jet from the underlying event•Constrains x range (probe one region at a time)•Probe predicted angular decorrelation of di-jets (width broadening)

(Qiu, Vitev PLB632:507,2006)

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Dihadron, Multi Parton Interaction(MPI)

At large forward rapidity range,

azimuthal-angular independent pedestal component

−> expected significant enhancement at central dAu collision

STAR PRL 97, 152302π0: |<η>| = 4.0, h±: |η| < 0.75, pT > 0.5 GeV/c

PRD 83, 034029M. Strikman, W. Vogelsang

Forward (Muon) – Mid rapdity, IdA

Phys.Rev.Lett.96:222301,2006

dAu 1.4< η <2.0

η < | 0.35|

No significant suppression or widening seen within large uncertainties!

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-2 < η < -1.4

Only away side peak seen due to rapidity gap

Mid-Forward Correlations

dAu

PHENIX central spectrometer magnet

Backward direction (South)

Forward direction (North)

Muon Piston Calorimeter (MPC)

Side View

dAu

p0s

p0 or h+/-

xgluon ~ 10-2 (0.008,0.04)

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Di-hadron Correlation, Mid-Fwd • Mid-rapidity triggered

|hmid| < 0.35, hfwd = 3.0-3.8

• Normalized by pi0 triggers and subtracted uncorrelated background (b0)• Due to large rapidity separation, only away side peak is seen.

PRL107, 172301 (2011)

• Central d+Au collision shows suppression of away side peak• No away side peak width broadening apparent

|hmid| < 0.35, hfwd = 3.0-3.8

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Away side peak widths broadening ?

Trigger p0: |h| < 0.35, 2.0 < pT < 3.0 GeV Trigger p0: |h| < 0.35, 3.0 < pT < 5.0 GeV

dAu 0-20%

ppdAu 40-88%

•Widths are consistent between p+p and d+Au (all centralities) within large statistical and systematic errors•No broadening seen (within errors)

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Forward-Forward Correlations h1,2 = 3.4

dAu

PHENIX central spectrometer magnet

Backward direction (South)

Forward direction (North)

Muon Piston Calorimeter (MPC)

Side View

dAu

Mostly Merged p0s

clusters

p0

xgluon ~ 10-4-10-3 (0.001, 0.005)

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Di-hadron Correlation, Fwd-Fwd • Forward rapidity triggered

• Central d+Au appears to show significant suppression• Angular broadening possible in central d+Au

hclus,p0 = 3.0-3.8

PRL107, 172301 (2011)

• Normalized by pi0 triggers and subtracted uncorrelated background (b0, ZYAM)• Minimum cluster separation cut decrease amount of near side peak

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JdA (Mid-Fwd, Fwd-Fwd)

Suppression of JdA increases withNcoll increasePT mid decreasePT fwd decrease

Suppression Larger in fwd-fwd than mid-fwd

Centrality dependent suppression

Suppression of JdA increases withNcoll increase

Note: points offset from true <Ncoll> to show pT dependence

PRL107, 172301 (2011)

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dcdab

pbpp

ap

d

cdab

AubAud

ad

pppairsppcoll

dAupairsdAu

dA

zzDxfxf

zzDxfxf

NJ

c

c

,)()(

,)()(

/

/

JdA versus RGAu ?

Low x, mostly gluons JdA High x, mostly quarksWeak effects expected ~ RG

Au

b=0-100%Q2 = 4 GeV2

xAu

EPS09 NLO gluonsEskola , Paukkunen, Salgado, JHP04 (2009)065

RGAu


Forward-Forward Mid-Forward

s

epepx TTfragAu

21

21

34

arXiv:1109.2133v1


“ Dihadron momentum imbalance and correlations in d+Au collisions”Initial- and final-state multiple interactions can affect dijet(dihadron ) production in p+A(d+A)

This model explains both suppression and broadening of away side peak well.

PHENIX JdA with model STAR Δϕ correlation with model

Recent model predict

Zhong-Bo Kang, Ivan Vitev, Hongxi Xing et al, arXiv(1112.6021)

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dAu

Summary


• d+Au collision at forward rapidity range enables us to study low-x physics

• PHENIX RdA , RCP of single hadron results showed suppression and consistent with STAR and BRAHMS data

• Di-hadron azimuthal angle correlation measurement • Large suppression of away side peak seen in forward-forward correlation

in d+Au relative to p+p (Jda)• More suppressed in most central collision

• Angular Broadening of away side peak• Mid-forward rapidity, no increase seen within errors• Fwd-Fwd, increase seen in STAR data, currently inconclusive in PHENIX

data• Measurements of JdA ~ RG

AU

• Recent model calculation for both JdA and away side peak width

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Backup slide

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Nuclear Shadowing models

N. Armesto Hep-ph/0604108v2

Centrality Selection

Charged particle track distribution representing 92% (+/- 2% systematic) of the 7.2 barn total Au+Au cross section.

We then select event classes based on geometry (number of participating nucleons) using the Zero Degree Calorimeter and Beam-Beam Counter.

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4040

PHENIX Muon Piston Calorimeter

Small cylindrical holes in Muon Magnet Pistons, Radius 22.5 cm and Depth 43.1 cm

SOUTH

PbWO4

North

)( 43 yyTd ee

s

px )( 43 yyT

Au ees

px

•Fwd-Fwd, x~(0.001,0.005)•Mid-Fwd, x~(0.008,0.040)•Mid-Bwd, x~(0.050,0.100)

d(forward) Au(backward)


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MPC PerformanceNorth MPC

Decay photon impact positions for low and high energy p0s. The decay photons from high energy p0s merge into a single cluster

Sometimes use (EM) clusters, but always corrected to 0 energy

Clusters 80% 0 (PYTHIA)

“Trigger”NearFar

Jet1

Jet2


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RCP and RdAu show strong rapidity dependence

Brahms data

Strong suppression at large rapidity (small-x)

More central, larger rapidity range 1/4/12 HEP2012@Chile

Quarkonia Suppression in A+A Collisions

Recent Gluon Saturation (CGC) calculations (arXiv:1109.1250v1) also leave room for QGP effects in A+A collisions• However, they do not help explain the stronger suppression at forward rapidity in A+A

y=-1.7

y=0

y=1.7

PHENIX y=1.7

PHENIX y=0

ALICE y~3.2

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J/ψ in d+Au – learning about CNM thickness dependence

Nuclear effects are dependent on the density weighted longitudinal thickness of Au

0

1( ) ( , )T Tr dz z r

The forward rapidity points suggest a quadratic geometry dependence.

Circle : Sys err.

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Yield Extraction Examples• Fitting function: Two Gaussian ( / ) + f w One Relativistc BW (r)

+Background (Defined by estimated shape)– f yields stable when fitting procedure changes– + r w yields using background subtraction (large uncertainty)

Smaller fitting range:0.5-2.5 GeVLarger parameter range

Estimated background

r f w

r f w

y>0, Centrality: 40-60 y>0, Centrality: 40-60

Larger fitting range:0.4-2.6GeVSmaller parameter range

451/4/12 HEP2012@Chile

Documents

Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 HEP2012@Chile 1