Photo-emission from sQGP

hardtofindcurtainΠολεοδομικά Έργα

16 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

86 εμφανίσεις

Photo
-
emission from
sQGP

Sang
-
Jin Sin

(
Hanyang

univ
.)


@
kitpc
, Beijing, 2010/10/22


Based on
K.Jo

+ SJS arXiv:1005.0200



X.Ge
, M. Matsuo,
F.Shu,T.Tsukioka
,
sjs

arXiv:0806.4460







Two main difficulties

in Nuclear Physics




* Coupling is large.


Hard to do reliable calculation





*
Many particle system


difficulty even at
lattice QCD



* Need New idea




AdS
/QCD : gives mean field theory that
does not require loop
calcuation
.


The
stonger

the better.


Penalty: it is Holographic (5d)


Originally N=4 SUSY

For the strong coupling problem,

the ans. is the Gauge/Gravity Duality

Consequences of
duality


Gluon dynamics is replaced by ads gravity.


Exact Correlation function

can be calculated by

the classical eq. (but in 5d curved space).




Transports (more later),



Phase transition(SC,CSB)

Relativistic Heavy Ion Collider


Au
-
Au collision


E~200
GeV
/nucleon


Seek quark
-
gluon plasma(QGP)

1010.10.22

Early interests: 4 puzzles


Perfect fluid : (
0806.4460

, 0901.0610

)


Jet quenching (
hep
-
th
/0607123
)


elliptic flow (
hep
-
th
/0610113
)

*


Early
thermalization

(
hep
-
th
/0511199

)


These are puzzles from the aspect of AF

but clues to use
AdS
/CFT
.

phenomena
-
(my contributions)

Usefulness of ads/
cft
:

understanding Perfect fluidity

B
k
s


4




/
s

0
.
1

h
/
k
B

While
perturbative

evaluation ~1/g^4

Exp:

ads/
cft

:

Universal
value

What about LHC?


Is the medium still strongly interacting ?


If mass production mechanism is too
efficient, increasing initial energy does
not help to increase the Temp. much.


For
Hadron

sprectrum
, we expect it is
the same as the RHIC since they
reprent

the moment of the
freezout
.





Photon & Lepton


On the other hand

photons and leptons can expose the
early stage of the fireball.


Photoemission spectral functions are
interesting. Strong
v.s

Weak are very
different.
(
Huot

et.al,
hepth
/0607237).


No density effect of the medium.

In this talk


Dense matter effect in Photoemission rate

based on the work with

KwangHyun

Jo.(my student)



Claim: density effect is yet another
interesting effect: LPM and beyond.


Understand why such dramatic change
happens.





Photoemission rate and duality
Huot

et.al
hepth
/0607237

Photo prod. in weak g


Sum of 2
-
2,
Bremstrahlung,pair

annihilation


LPM effect yet to be corrected

Lepton production

SYM
v.s

QCD in weak g


Huot

et.al
hepth
/0607237

Zero density result

Huot

et.al
hepth
/0607237

Finite density

K.Jo

+ SJS

arXiv:1005.0200



density effect in spectral function

To understand Why,






Look Hydro dynamic analysis
,
which gives the analytic result for the
spectral function for small w and k.







In
hqcd



Finite temperature quark
-
gluon plasma



Black hole


Dense matter


Charged

black hole


we use RN
balck

hole. (for

the
relevance to the baryonic system,

see
[
arXiv:0707.2719

(
sjs
)
]

Bulk filling
brane

idea.


AdS R
-
N black
hole



Solution to the eq. of M:

Match: BH


QGP


T
emperature
, entropy, energy





pressure
, charge density and chemical
pot.

Perturbations around
RN


perturbed
Eintein

eq
. & Maxwell eq.







X.Ge
,
Y.Matsuo
,
F.Shu
,
SJS,
Takuya

Tsukioka

,
arXiv:0806.4460



perturbed Maxwell eq.






Gauge choice and Fourier mode






Classification of
modes(for graviton)

Vector type
pert and mode mixing.

























Infalling

BC at
horizon


Causal
Gr.F


perturbative

solution near
boundary








Hydrodynamic

Mixing effect:

Correlation functions in hydro limit

transverse
v.s

longitudinal





Remark


In the absence of charge,


particle current is NOT diffusive


(a=0 or T=0)

while heat current is !

Summary of hydro



Result:
Density causes Mode Mixing,

which establishes diffusion pole.

We expect that it
enhences

spectral
function of photon at low frequency.

Density effect in
photo
emmision

LPM(Landau
-
Pomeranchuk
-
Migdal
)

Suppression of
Brehmstrahlung

due to the
density effect. (B is not point like
process)

Q: Is it encoded here? We think so.

Decrease in the peak at low density.

Notice: after certain critical density,
photoemission increases.

Some details for spectral function
calculation

for vector mode

Effective action4

In falling BC at horizon: D=0,C=1


relevant case

introduce


density effect in spectral function
(again)

Ac and DC
Conductivities

Density effect in
spectral function

Remember:

The hydro peak is absent if density is 0.

Conclusion


String theory may be useful for the New
experiment.


Photoemssion

spectral curve is

Analogy of CMBR curve in cosmology



LPM effect is counted and different
high density effect is predicted.