Dileptons and Photons at Collider Energies

Dileptons and Photons at Collider Energies

K. Dusling, C.H. Lee and I. Zahed.

BNL14

Outline

• Motivation• Rates, • Evolution• Experiments

Na45: 95’

Na60:03’

Phenix: 07’

Star: 13’

Formally

time

evolution rate

acceptance

Rates: Hadrons

Equilibrium averaging

Hadronic Expansion

In Diagrams

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

a

d d4 x e iqx ina (k)T*J (x)J(0) in

a (k)

is,I

dN d4 x e iqx N ins,I (k)T*J (x)J(0) N in

s,I (k)

1,2,3,

…-Pi,

Resonance Gas

1,2,3-N l

l

,,,, 11 Ka

ia

d d4 x e iqx ina (k)T*J (x)J(0) in

a (k) + …

ll

N

N

,

,N ,N

is,I

dN d4 x e iqx N ins,I (k)T*J (x)J(0) N in

s,I (k) + …

l l

l l

,,

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

Vector-Axial Mixing: κ

d3k n(k0)

(2 3)2k0 f2 W1

F (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 ina (k)T*J (x)J(0) in

a (k)

Chiral Limit and zero-mtm pion:

κ

Data :

V (q2) 0 TVV 0

A (q2) 0 T jAjA 0

e+e-

Decay

.

VA-Mixing explicitly

Dey, Eletsky, Ioffe 96

Vector Spectral Function

2-pion Final state:

Electric Conductivity:

Hadronic vs Lattice:

Flavour Susceptibility:

in details:

Flavour Susceptibility:

Rates

Rates: 1 Nucleon

:

=

1 Loop ChPT N- Transition

I

N

F

N smspqWe )()(4),( N

tot

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

Typical Mixing in

a1a1

T=150 MeV μb=225 MeV

Rates: sQGP

sQGP:

ImW11R

1

4NC eq

2

q

q

2 12Tq

lnn

n

l+

l-

l+

l-

ImW11R

1

4NC eq

2

q

q

2 s

A4

2 4 2

Tq

n 1 n n 1 n

Hansson and Zahed 91’

Electric Conductivity

sQGP Rates

Evolution

Sample hydro evolution

Faster cooling x higher rates: same

V2 Flow @ 2.76 TeV

Dileptons: NA60, Phenix, Star

NA60 : dN/dη=140 95’

Pt Spectra: low

Pt Spectra: High

PHENIX

Beam Energy Scan: STAR 13’

Photons: WA90, PHENIX

WA98

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

PHENIX

RHIC1 RHIC2

PHENIX extrapolation: γ

PHENIX: M<<qv

1 15% Systematics!

V2 PHENIX

Achievements

1. EM “OK”*

2. LxR “restored”

3. QGP “visible”

4. V2 “low”

(* π < < ρ)