Dileptons and Photons

K. Dusling and I. Z.

BNL 09

Outline

• Motivation• Rates• Evolution• Experiments

NA45: 95

NA60: 03

Phenix: 07

Rate: Formally

Acceptance: NA60 vs PHENIX

Hadronic Rates

Dilepton Production

)0(),()()(

41

21

604

2

2

2

2

23

2

4

JxJxexdqWqm

qm

qqddR xiqll

)0()()( with )(Im1

2),( *4

/

00

JxJTexdiqWqW

eqqW xiqFF

Tq

l+

l-

l+

l-

Expand in Stable Hadrons

i d4 x e iqx 0T*J (x)J(0)0 i

a d d4 x e iqx in

a (k)T*J (x)J(0) ina (k)

is,I dN d 4 x e iqx N in

s,I (k)T*J (x)J(0) N ins,I (k)

+2+3, …-Pi, +2+3, …-K

Resonance Gas: J=ρ+ρ’+..

+2+3, …-N

Many Feyman Graphs:

l l

l l

,,

i d4 x e iqx 0T*J (x)J(0)0 + + …

l

l

,,,, 11 Ka

ia d d4 x e iqx in

a (k)T*J (x)J(0) ina (k) + …

ll

NN

,

,N ,N

is,I dN d4 x e iqx N in

s,I (k)T*J (x)J(0) N ins,I (k) + …

How to reduce

V a (x) iS t Sv

a (x)

Aa (x) iS t Sa

a (x)

Asymptotics: Broken CS

Aa f in, out

a (x) x 0

Aa fm

2 in, outa (x) x 0

In Practice: NF=2

d3k n(k0)(2 3)2k0 f

2 W1F (q,k)

W1F 12q2 ImV (q2)

6(k q)2 ImA[(k q)2]

8((k q)2 m2q2)ImV (q2)Re[R (k q)]

(q q)

ia d d4 x e iqx in

a (k)T*J (x)J (0) ina (k)

Chiral Limit and zero-mtm pion:

)()(Im12)0,( 2221 qqqqW AV

F

VA Mixing=LxR Restoration?

V (T)(1 )V (0)A (0)

A (T)(1 )A (0)V (0)

T 2

6 f2

Dey, Eletsky, Ioffe 96

Expansion Parameter:

n2m f

2

n 3 d3k(2 )3 n(k )

= 0

0

Dilute!

2-pion Final state:

2-pion Final state:

ΠV and ΠA

Data :

V (q2) 0 TVV 0

A (q2) 0 T jAjA 0

e+e- Decay

.

1 Nucleon Final State

:

=1 Loop ChPT N- Transition

I

NF

N smspqWe )()(4),( Ntot

22

WNF (q)i d4 x e iqx N in

s,I (k)T*J (x)J(0) N ins,I (k)

s,I

+

:*

Input at the Photon Point

N background 00 22 qq

VA Mixing in

T=180 MeV

VA Mixing in

a1a1

T=150 MeV μb=225 MeV

QGP Rates

wQGP:

ImW11R

14

NC eq2

q

q

2 1 2Tq

ln nn

l+

l-

l+

l-

wQGP:

LPM Effect: Aurenche et al 02

wQGP: γ

Collinear Enhancement+ LPM Effect : Arnold, Moore, Yaffe 01

sQGP: OPE

ImW11R

14

NC eq2

q

q

2 s

A4

2 4 2

Tq

n 1 n n 1 n

n1/(e(q 0q ) / 2T 1)

Hansson and Zahed 91

Hydro Evolution

Hydro Parameters

SPS, RHIC and LHC

Fireball: NA60

TC 160 MeVs /nB 42Tf ,o. 120 MeV

LH = 6 GeV/fm-3

Thermal Freeze-out

Cooper-Frye

Chemical Freezeout:

Fireball cools faster x Rates higher = w/μπ !

NA60

NA60 : dN/dη=140

Pt Spectra: Intermediate

NA60 dimuons : Upshots

1. Hadronic emission dominant: VA mixing 2. Partonic emission small: tiny QGP 3. Blue shifted spectra (M=rho): small Lh?

Phenix: Dileptons

pT spectra: Wπ+Wππ

MIGHTY FILTER!

PHENIX

Dusling+Z 07 Dusling+Z 09

PHENIX DI-electrons : Upshots

1. Hadronic large but Filtered: M<500 MeV 2. Partonic large and dominant: 100<M<250 !!3. Hadronic large and dominant: M=ρ-ω-φ4. Non-thermal emission: 300<M<500 MeV.

Another DLS-like puzzle?

Phenix: Photons

Versus Kinetic

Turbide, Rapp, Gale 04; Liu, Rapp 07

WA98

0<qT (GeV) <4 0<qT (GeV)<0.8

N:x2

Rates at RHIC

RHIC1 RHIC2

PHENIX

RHIC1 RHIC2

PHENIX extrapolation

Systematics of the Extrapolation

15% Systematics!

LHC: √s=5.5 TeV

0<qT(GeV)<2 1<qT (GeV)<5

WA98 and PHENIX Photons : Upshots

1. WA98: Hadronic emission of photons dominated by hadrons: M<2 GeV

2. PHENIX, LHC: Hadrons dominant for M<1GeV. QGP ‘visible’ around 1.5GeV.