news from phenix on extremely dense and hot matter

News from PHENIX on extremely dense and hot matter

B. Jacak

Stony Brook

April 24, 2009

2

Some (selected) news from PHENIX

Initial state (in honor of Larry)Parton structure of nucleusInitial temperature achieved

Di-lepton emission

Interactions within the plasma

(in honor of Jean-Paul)Color screening: J/, (!)Opacity & energy loss

New data to constrain the imaginationof our creative friends

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3

@forward rapidity with mid-rapidity hadron trigger

Color Glass Condensate suppression of pairs broadening of correlation

Kharzeev, NPA 748, 727 (2005)

PT is balanced by many gluons

Dilute parton system

(deuteron)

Dense gluon

field (Au)

shadowing (non-LT)suppression of pairs vs. singles

Vitev, hep-ph/0405068v2

Suppression of hadron pairs in d+Au

Sharing of gluons by near neighbor nucleons

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Mike Leitch - PHENIX QM09

4

Pairs are suppressed vs. p+pLarger suppression for more central d+Au collisions

Correlated particle yield (forward)

π0

Triggerπ0 or h±

Aud

Y<0 Y>0

[ ][ ] )0()0()5.3(

)0()0()5.3(

==+=

==+==

++

++

ηηη

ηηηtrig

pppair

pp

trigAud

pairAud

dAu NN

NNI

Ncoll

I dA

u

Associate π0: 3.1<η<3.9 pT = 0.45-1.59 GeV

2008 data

5


5

Preliminary data say - No significant signal for: large broadening centrality dependence for mid-rapidity π0

pp

dAu0-20%

dAu40-88%

π0

Triggerπ0 or h±

Aud

Y<0 Y>0

Correlation width

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6

• Exponential fit of pT:Tavg = 221 ±23 ±18 MeV• Multiple hydro models reproduce data •Tinit ≥ 300 MeV

arXiv:0804.4168v1 [nucl-ex]

Initial State Temperature: direct photons

Low mass, high pT e+e-

nearly real photons

Large enhancement above p+p in the thermal region

7

Lepton pair emission EM correlator

Emission rate of dilepton per volume

Boltzmann factortemperature

EM correlatorMedium property

ee decay

Hadronic contributionVector Meson Dominance

qq annihilation

Medium modification of mesonChiral restoration

From emission rate of dilepton, the medium effect on the EM correlator as well as temperature of the medium can be decoded.

e.g. Rapp, Wambach Adv.Nucl.Phys 25 (2000)

q

q

Thermal radiation frompartonic phase (QGP)

Yasuyuki Akiba - PHENIX QM09

8

Relation of dileptons and virtual photons

Emission rate of dilepton per volume

Emission rate of (virtual) photon per volume

Relation between them

Virtual photon emission rate can be determined from dilepton emission rate

For M0, n* n(real) so real photon emission rate can also be determined

M x dNee/dM givesVirtual photon yield

Dilepton virtual photon

Prob. *l+l-

This relation holds for the yield after space-time integral


9

Theory prediction of dilepton emission

Vacuum EM correlatorHadronic Many Body theoryDropping Mass Scenarioq+q annihilation (HTL improved)(q+gq+qee not shown)

Theory calculation by Ralf RappdMdydpp

dN

tt

ee at y=0, pt=1.025 GeV/c

Usually the dilepton emission is measured and compared as dN/dptdM

The mass spectrum at low pT is distorted by the virtual photonee decay factor 1/M, which causes a steep rise near M=0

qq annihilation contribution is negligible in the low mass region due to the m**2 factor of the EM correlator

In the calculation, partonic photon emission processq+gq+q+e+e- not included


10

Virtual photon emission rate

dydpp

dN

dMdydpp

dNM

tttt

ee*∝× at y=0, pt=1.025 GeV/c

dydpp

dN

tt

Vaccuum EM correlatorHadronic Many Body theoryDropping Mass Scenarioq+q annihilaiton (HTL improved)(q+gq+qee not shown)

The same calculation, but shown as the virtual photon emission rate.

The steep raise at M=0 is gone, and the virtual photon emission rate is more directly related to the underlying EM correlator.

When extrapolated to M=0, the real photon emission rate is determined.

q+gq+* is not shown; it is similar size as HMBT at this pT


11

Excess of virtual photon

Excess of electron pairs over the cocktail ~ constant with mass at high pT.

Excess converted to virtual photon yield via divided by 1/M shape from the virtual photon decay.

The distribution is ~flat over half GeV/c2

Extrapolation to M=0 should give the real photon emission rate.

No indication of strong modification of EM correlator at high pT !

presumably the virtual photon emission is dominated by processes e.g. ++* or q+gq+*

Exc

ess

*M (

A.U

).


12

Large low mass dilepton excess at low pT

0 < pT < 8 GeV/c 0 < pT < 0.7 GeV/c

0.7 < pT < 1.5 GeV/c 1.5 < pT < 8 GeV/c

Low pT shape of the excess seems incompatible with aconstant virtual photon emission rate…Large enhancement of EM correlator at low mass, low pT?


13

Quarkonia (cc, bb bound states)

Important production channel: g+g fusionSensitive probe of gluon density, distribution + plasma

Lovely idea:Probe plasma (color) screening length using different

radius bound states

Alas, Mother Nature can be nasty!They decay into each other, making spectroscopy

more complicated

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J/ in Au+Au

Suppression at RHIC ~ at SPS! What is pT dependence?

Simple color screening: low pT J/ lost, higher pT not Helmut Satz & friends <1990

AdS/CFT (“hot wind” break up): Liu, Rajagopal,Wiedemann PRL 98, 182301(2007)

Regeneration (2-component): Zhao, Rapp hep-ph/07122407 & private communication

Equilibrating Parton Plasma: Xu, Kharzeev, Satz, Wang, hep-ph/9511331

Gluonic dissoc. & flow: Patra, Menon, nucl-th/0503034


15Mike Leitch - PHENIX QM09

15

pbdy

dBR y

464535.0|| 114| +

−< =∗σ

Upsilon in p+p

Cross section follows world trend

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Au+Au

RAA [8.5,11.5] < 0.64 at 90% C.L.


16

p+p Au+Au

N[8.5,11.5] 10.5(+3.7/-3.6) 11.7(+4.7/-4.6)

NJ/Ψ 2653 ±70±345 4166 ±442(+187/-304)

RAA(J/Ψ) --- 0.425 ±0.025±0.072

Upsilon suppressed in Au+Au!

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RAuAu(y=0)

J/Ψ 0.425 ± 0.025 ± 0.072

8.5<M<11.5 GeV < 0.64 at 90% C.L.

• σabs of ~1/2 of J/Ψ : E772 (PRL 64, 2479 (1990))

• E772 nuclear dependence corresponds to RAuAu = 0.81

• Lattice expectations in Au+Au - 2S+3S suppressed: RAuAu = 0.73

• absorption x lattice ~ 0.73 x 0.81 ~ 0.60 ??? need serious theory estimate instead of this naïve speculation!

• e.g. Grandchamp et al. hep-ph/0507314

ALSO:• in anti-shadowing region

• CDF: 50% of from b (pT>8 GeV/c) & ~25%? at our pT

• PRL84 (2000) 2094

as onium melting baseline…

Should ’s be suppressed?

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Quarkonium spectroscopy

This long awaited era has arrived

RHIC Run-10 in 2010 increased statistical reach

The devil is in the details!As usual…Getting it all right is a challenge/opportunity for

theory!

The data will constrain correlations among heavy quarks in the strongly coupled (strong correlated!) matter at T = 2-3 Tc

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Interactions within the plasma

Experimentalist’s simple minded picture

Strong coupling = interactions among multiple neighbors

Of course this causes correlations within plasmaalso increases opacity

so, is the quark gluon plasma “black”?

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High-pT v2arXiv:0903.4886 (Run-4

data)

Carla Vale - PHENIX QM09

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pT

NPart

RA

A

• Out-of plane RAA nearly flat with centrality at low pT

• In- and out-of-plane converge at high-pT (~10GeV/c)

Out-of-plane vs. in-plane

in-plane

intermediate

out-of-

plane


Run-7

22

Away-side yield RP dependence at high-pT

in-plane

out-plane

AwayPTY

0 πφs

π

π

PTY

= p

er-

trig

ger

yie

ld

Penetrating production in-plane

out-plane

π

π

AwayPTY

0 πφs

Tangential production


23

Away side yield

Away side yields drop from in-plane to out-of-plane: favor penetrating production picture


Medium is gray, not black!

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The way forward

p+p slope:

6.89 0.64

Au+Au slope:

9.49 1.37

fragmentation of tagged jets in/out of medium

Challenge: understand energy transfer to/from the medium! Coupling properties…

25

Upgrades* increase direct jet tags, heavy quarks

PHENIX Upgrades

Forward Calorimeter at = 1-3 Tagged-jet correlations Increased acceptance

Silicon VTX, FVTX Tag displaced vertex for heavy quark decaysTrack charged hadrons

*In addition to RHIC-II luminosity upgrade x8

26

Conclusion:

Happy Birthday Larry!

Happy Birthday Jean-Paul!

More fun awaits!

Need your help if we are to get…

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backup slides

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Local Slopes of Inclusive mT Spectra

Data have soft mT component not expected from hadron decays

Note: Local slope of all sources!need more detailed analysis

Axel Drees28

Soft component below mT ~ 500 MeV:

Teff < 120MeV independent of mass

more than 50% of yield

Tdata ~ 120 MeV

Tdata ~ 240 MeV

29

J/ in p+p and d+Au

EKS; σCNM = 0,1,2,3,4,…15 mb

%8860%8860

%200%200

%200

−−

−−− =

collinv

collinvCP NN

NNR

30

v2 Comparisons to Geometric Models

V. Pantuev: arXiv:hep-ph/0506095

Corona effect, L ~ 2fm;

J.Liao and E.Shuryak: arXiv:0810.4116

Stronger jet quenching at near-Tc region;

E.Shuryak: PRC 66 027902 (2002)

Geometric limit: v2(high pT) < v2max(b)

Too large for a pure “jet quenching” A.Drees, H.D.Feng, J.Jia: Phys.Rev.C71:034909,2005

Jet absorption proportional to matter density;

Can’t reproduce the large v2.

Rui Wei - PHENIX QM09

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σ determined three different ways:• single electron spectra methods:

• cocktail subtraction• converter

• di-electrons

Muon measurement at forward rapidity is consistent

ccσ

bbσ

dσ h

eavy/d

y (

mb

)

Open Heavy Flavor

32

b quarks and medium effects…

B meson spectra

e-h correlations totag D vs. B decays

b + c !

Oh oh!

33

04/02/2009 Quark Matter '09 Y. Yamaguchi

Should modify low pT direct yield→ Evaluate using d+Au data.

Systematic errors on Run3 d+Au results are still large.At 2-3 GeV/c, data looks in agreement with pQCD calculation.

→ No modification of direct yield by nuclear effects?

Run 8 analysis underway: x30 statistics

33/12Nuclear Effects

34

Calculations by S.Bass et al in arXiv:0808.0908

Comparing to energy loss models II


35

Do both jets shock the medium?

p+p

centralAu+Au

3<pt,trigger<4 GeV

pt,assoc.>2 GeV

Au+Au 0-10%

preliminary

STAR

36

Both ridge & shoulder yields grow

QuickTime™ and a decompressor

are needed to see this picture.

37

Away/near to ~ cancel acceptance



Shoulder and ridge have the same physics!See also Rudy Hwa, Jiangyong Jia recent talks

38

From the bulk or jet-like?

arXiv:0712.3033

arXiv:0712.3033

Answer:it’s more like the bulk! QGP-like

PHENIX PRL 101, 082301 (2008)

pT spectra

Particle content

39

“probe” particles: q or g, resulting in hadron jet

pT < 1.5 GeV/c

“thermal” particles radiated from bulk of the medium

pT > 3 GeV/c

jets (hard scattered q or g)heavy quarks, direct photonsdescribe by perturbative QCDproduced early→“external” probe

q

q

leading particle

40

(shear generallya phenomenonin crystals butnot liquids)

Are shocks in strongly coupled EM plasma.So sQGP could also support shockwaves

41



42

In the most central collisions

43

Jet reconstruction in Au+Au

Seeded cone and kT algorithms;Correct for underlying event







44

Radiated photons Tinit

exp + Ncoll scaled pp

Fit to pp

NLO pQCD (W. Vogelsang)

In p+p: pQCD works to low pT

In Au+Au: soft (thermal) excess

fit with exponential

T = 221 ± 23 ± 18 MeV (central)

T = 224 ± 16 ± 19 MeV (MB)arXiv: 0804.4168

45

Tinit > Tc !

To unfold hydro evolution:

Compare to photon spectrum from hydro models

T decreasing with time

Tinit ~ 300-600 MeV

Tc ~ 170 MeV

D’Enterria & Peressounko, EPJ C46 (2006) 451

Tinit (MeV)

tim

e

(fm

/c)

G. David

46

Quantifying the viscosity

Need:3-d viscous hydro calculationsPrecision dataMass dependence of v2

+ other observables for pT transport

pT (GeV/c)

v2/s ~ 0 - 0.8Recall: in ideal hydro mfp=0Conjectured /s bound: 1/4

Work is underway to control: initial state geometry gluon distribution

€

~ n p λ mfp

Romatschke & Romatschke, arXiv:0706.1522

PHENIX Preliminary

47

p+p Au+Au (MB)Gluon Compton

q

g q

e+

e-

Dileptons at low mass and high pT

•m<2 only Dalitz contributions•p+p: no enhancement •Au+Au: large enhancement at low pT

•A real source virtual with v. low mass•We assume internal conversion of direct photon extract the fraction of direct photon

PHENIX Preliminary PHENIX Preliminary

1 < pT < 2 GeV2 < pT < 3 GeV3 < pT < 4 GeV4 < pT < 5 GeV

r : direct */inclusive *

Direct */Inclusive * determined by fitting each pT bin

( ) ( ) ( ) ( )eedirecteecocktaileedata MfrMfrMf ⋅+⋅−= 1

48

direct photons via e+e-

for low mass, pT > 1 GeV/c

direct * fraction of inclusive *

(mostly , ) is real fraction

of (mostly , )

low mass and pT >> mee

dominated by decay of *

mee

hadron cocktail

49

High pT photons in heavy ion collisions

Should be the reference, but they are modified:Isospin effect (n≠p)+ cold nuclear effect (EMC from EKS)+ eloss 20 < ωc < 25GeV (from quarks)

50

Virtual Photon Measurement

Case of Hadrons

Obviously S = 0 at Mee > Mhadron

Case of direct *

– If pT2>>Mee

2

Possible to separate hadron decay components from real signal in the proper mass window.

Any source of real can emit * with very low mass. Relation between the * yield and real photon yield is known.

α

SdNMM

m

M

m

dM

Nd

eeee

e

ee

e

ee

121

41

3

22

2

2

22

⎟⎟⎠

⎞⎜⎜⎝

⎛+−=

S : Process dependent factor

( )3

2

222 1 ⎟⎟

⎠

⎞⎜⎜⎝

⎛−=

hadron

eeee M

MMFS

1=S

Eq. (1)

51

Where does the lost energy go?

Radiated particles still correlated with the jet

Completely absorbed by plasmaThermalized?Collective conservation of momentum?

Excites collective response in plasmaShocks or sound waves?Wakes in the plasma?

news from phenix on extremely dense and hot matter

Documents

dilepton emission rate

real photon emission

low pt

high pt e e

hadron pairs

em correlatorin

low mass region

exponential fit of pt