1
Theory Overview of QGP and Cold Nuclear Matter Effects at
RHIC
Ivan Vitev
GHP Satellite Workshop, October 22 – 24, 2006APS, DNP fall meeting, Nashville, Tennessee
2
Cronin Effect in p+A Reactions
Default
0d Au X
Good description at mid rapidity
I.V., Phys.Lett.B526 (2003)
• Cronin effect
A.Accardi, CERN yellow report, references therein
0Au Au X
0
21
-2
1
1- - ..( ) ( ).
!-
niel
n
in e ii
nf
l
dd qdN e d
nq
d qNp qpc s
sc¥
= =
= å Õò2( ) ( )i k kdN d
^ ^=
2
2
2
1,( )
2
k
f edN k
cmx
mp xc
^-
^= /Lc l=
Initial condition Solution Mean number of scatterings
2
2 2
2
2
For 2
med
tot vac med
k
k k k
cmx^
^ ^ ^
D =
D = D + D
The approximate solution is that of a 2D diffusion
Implemented in the PQCD approach as kT broadening of the initial state partons
Scales: 0 ~ 1 2T QCDQ p Q GeV
3Kharzeev, Kovchegov, Tuchin, hep-ph/0405045
Brahms hadron forward suppression pattern
Gluon Saturation ModelsLo
wer
x
Gribov, Levin, Rishkin, Phys. Rep. (1980)
• Nonlinear gluon evolution 2 to 1 processes
• Particle production via 2 to 1 processes (monojets)
BRAHMS collab., Phys.Rev.Lett. 93 (2004)
Note: are these monojets?
J.W.Qiu, I.V., Phys.Rev.Lett. 93 (2004)
Nuclear Shadowing
Longitudinal size: 1/ 2 Nm xIf then 0z r 0.1x
Deviation from A-scaling: A A
2
2BN
Qx
m
00
2 20
2 2
(0) ( )1
( , )2
1 ( , ) ( )
2
2i
ff
f f
x
sf
T Q Q d e px
x
p
Q
F
Q
p
O
S.Brodsky et al, Phys.Rev.D65 (2002)
• Shadowing is dynamically generated in the hadronic collision y coherent final state scattering
• Simplistic view: modification of the nuclear wave function
Alternative model: “leading twist”2~ lnQ
222 ( ) 2 ( ) 2
2
1/
2
3( 1)( , ) , = 1 ,dynLT LTA
T T T
mxF x Q F
Ax Q F x Q
QA
QA
5
Evidence for Energy Loss
something more, dE/dx? &
more?
= X1 – X2
19 GeV
39 GeV
200 GeV
J/ for different s collisions
M.Leitch et al. PHENIX,EA866 and NA3 data
1 2, 1Fx x if x
A NA Cross section scaling:B.Kopeliovich et al. hep-ph/0501260
• Energy loss is a dominnant mechanism in the forward rapidity / large xF suppression
p, x1 A, x2
xF
S.S.Adler et al., nucl-ex/0603017
6
Nuclear Effects at Forward Rapidity
• Note the different contributions to an overall suppression effect
I.V., in preparation (2006)
S.S.Adler et al., nucl-ex/0603017
• The most detailed calculation do far at forward rapidity
• Original incoherent result:
I.V., T.Goldman, M.B.Johnson, J.W.Qiu, Phys.Rve.D74 (2007)
G.Bertsch and F.Gunion, Phys.Rev.D (1982)
0
(1) lng
E L Econst
E Q
0
(2) lng
E L Econst
E Q
• Original incoherent result:
Six fold cancellation
Extreme radiation length
(2) 1
(1) 6
const
const
0 100X fm
7
Particle Production Mechanism
OK
• Excludes: all the monojet color glass phenomenology, large final state energy loss
• Compatible with: Dynamical shadowing, initial state energy loss, leading twist shadowing parameterizations
Dijets:
Monojets:
1
2
2
1
1
2 21 2 1
11/
1 2/1min
2
222
2
1
( ) (( )
) ( )( ) h c
h d
a sb
abcd aT T b
ab cdN
T T z
h hN
D zdz D z
x x
p p x
d
dydyd p d p SM
z x
ffd j p as®
D -= å ò
8
The QCD Phase Transition
J.P.Blaizot,E.Iancu,A.Rebhan, Phys.Lett.B470, (1999)
• Hard thermal loop calculations: improved resummation of the perturbation series
• Agreement between HTL and Lattice for
3 cT T
F.Karsch,E.Laermann,A.Peikert, Phys.Lett.B487, (2000)
Asymptotic freedom:
Note on LHC versus RHIC: strongly versus weaklycoupled plasmas, beware of logarithmic running
2T gT g T
Note: recent results Tc~ 190 MeV vs Tc~ 175 MeV
• Deviation from Stefan-Boltzman: the log running of s
9
Relativistic Hydrodynamics
( ) ( ) ( )
( )
( ) ( ) ( )
( ) ( )
u x
T x u x u x g
j
x
x u x
p p x
n
x
0
0
( )
( )
T x
j x
x
yz
2 2 2
11 2 (cos ) .2 ..
2
h h
T T
dN dN
dyd p dydv
d p
P.Kolb,J.Sollfrank,U.Heinz, Phys.Rev.C62, (2002)
Elliptic flow
• Favors: EoS with QCD phase transition, low viscosity, early thermalization high energy density
0 1 fm 3
0 15 /GeV fm
Ideal hydro, initial conditions
10
Plasma Instabilities. Strikland
Current filamentation
Vlasov equation:
Yang-Mills equation:
Note on time scales: t = 10 fm, still too large
11
Energy Loss in the QGP
R.Baier et al. Nucl.Phys.B (1997)
M.Gyulassy, P.Levai, I.V., Nucl.Phys.B594, (2001) Phys.Rev.Lett.85, (2000)
M.Gyulassy, X.N.Wang, Phys.Rev.Lett.68, (1992)
• The most important effect in dense nuclear matter: QGP but also cold nuclei
(1) R s
3(1)
2
2g
g
2R s
2CE Log ... ,
4
Static medium
9 C 1E Log ... ,
4 A
(L)
dNdy (L
1+1D
)
L 2E
Bjo
L
2EL
L
rken
p
k xp k
1q 1q 2q 3q 4q5q 5q 6q 6q 7q
f
LPM = Landau-Pomeranchuk-Migdal
0
raddE E
dz XQED: QCD:
12
System Size Dependence of Jet Quenching
I.V., Phys.Lett.B 639 (2006)
• In classes with the same we find numerically the same suppression
partNAAR
(For example central Cu+Cu and mid central Au+Au)
1' 2 2
/ /
0
12
/
0
(1 ),(1 )
1( , ) ,
1 1
1
( )
) + ,(
cc c c
vach q h q
vacg
h g
zp p z
zD z Q d D Q
zd D Q
P
dN
d
Identifying nuclear effects:
1
i
i
E
E E
( )P Probability density -
0A A X
TNN
TAA
collTAA dpdd
dpdd
NpR
/
/1),(
2
2
13
Jet Tomography
I.V., M.Gyulassy, Phys.Rev.Lett. 89 (2002)
F.Karsch, Nucl.Phys.A698 (2002)
SPS RHIC LHC
0 0
' / ( ') ' ( ')
0 0
( ')
( )
r r
abs absdr r dr r r
I r I e I e
Principles of jet tomography
14
Hard Processes
11
2
/1 1 2
1 1
1
2min min 1
2( )(
()
))(
a b
sa b a b
ab
h
cd a bx x
ab cT
dc
hNNd
dx dD z
zx x x
x x Sd pM
ydas
ff ®= å ò ò
5 10pT [GeV]
15
0S.Turbide et al., Phys.Rev.C72:014906,2005
V.Wogelsang et al., Phys.Rev.D Note: prompt versus fragmentation photons
qg q qg qg
/ ( )qD z
• Particle production: processes
• Direct photons: no final state interactions and no attenuation
2 2
15
• Cancellation of collinear radiation
large angle soft gluons and correspondingly more soft hadrons
• It is broad but is it dipped?
I.V., Phys.Lett.B630 (2005)
What Happens to Medium-Induced Radiation
In A+A
+2Re
2
x
2 *2 Resin *
...gmed
a b c
dNM M M
d d d
0, / 0k k
S.Pal, S.Pratt, Phys.Lett.B574 (2003)
Note: strong theoretical arguments againstStrong “dip”
16
Mach Cones and Sound Velocity
A.Chaudhuri, U.Heinz, Phys.Rev.Lett. 97 (2006)
J.Casalderrey-Solana et. al, Nucl. Phys.A774, (2006)
F. Karsch, hep-lat/0601013
<cs>~ 0.35 Soft EOS
• Hydro simulations do not confirm such mechanism
• There is no realistic simulation of the di-jet distributions yet!
17
S. Wicks et al., nucl-th/0512076
Heavy Quark Production and Modification
• Single electron measurements (presumably from heavy quarks) may be problematic
• Problem: treated in the same way as light quarks! D B
10 fm 1.0 fm 0.35 fm( 10 )f Tp GeV
2 2 2
1 (0.2 . ) 2 (1 )
(1 ) (1 )h q
GeV fm z z py
p k z m z z M
• Interactions beyond the partonic level
M.Djordgevic, M.Gyulassy, Nucl.Phys.A (2004)
11
(1 ) (1 )
2
2 22
2 2
22
2
,g
n ngm x M
m
xE
k k k
x Mx
p Ek k
• Significant interest in collisional energy loss
Note: what is important is consistent evaluation ofcollisional versus radiative E-loss
18
Diffusion and Dissociation of Heavy Mesons
• Langevin simulation of heavy quark diffusion
H.van Hees, I.V., in preparation
• B is significantly less quenched than D
Drag coefficient:1 i
ii
pA
p t
t [fm]
Su
rviv
al p
rob
ab
ilit
y
exp /s dissP t
D
B
~ 1.7B fm
~ 3.7d fm
/ 0.2, / 0.35b c
E E E E
A.Adil, I.V. in preparation
Prelim
inary
D(B) meson
• B is comparably quenched to D
Prelim
inary
• Collisional dissociation of heavy mesons
19
Conclusions
Quark-gluon plasma effects: LQCD predicts Tc=175 – 190 MeV, no colored bound states. EoS consistent between LQCD and HTL. Deviations from SB, log running of alpha Hydro simulations of v2 suggest early thermalization, e0 = 15 GeV/fm3 Non-Abelian plasma instabilities: path to isotropisation, time still too long Final state non-Abelian energy loss in the QGP is the dominant jet quenching mechanism. Tested against p+A and direct photons Jet tomography: e0 = 15 GeV/fm3 based on successful PQCD predictions Energy redistributed in soft particles. Mach cones? Strong theoretical arguments against. Lack of accurate simulations. Heavy flavor still problematic, highlights collisional E-loss. New mechanisms should be explored. Collisional dissociation of mesons, promising.
Cold nuclear matter effects: Particle production consistent with hard parton scattering, no monojets Nuclear effects arise dynamically from elastic, inelastic and coherent multiple parton scattering “Leading twist” versus “high twist” shadowing theory from final state interactions. Test at EIC. Bring a broader community to EIC Theoretical advances in understanding energy loss in cold nuclear matter. It appears to be a dominant effect at forward rapidity p+A reactions p+A program at RHIC II, vary C.M. energy. Advance theoretical models
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