Transcript Hwa-QM08 - University of Oregon

Physics Revealed at
Intermediate pT
Rudolph C. Hwa
University of Oregon
Quark Matter 2008
Jaipur, India
February 6, 2008
low
intermediate
2
hydro
high
6
no rigorous
theoretical
framework
pT
pQCD
But that is where the action is,
albeit experimental.
What can we learn from the abundant data?
2
Overview
Single particle distribution

pT
B/M ~ 1
p

RCP
 RCP
,
CP
R
K ,
CP
R
v2  ET 
nq  nq 

universal
(dAu) quark number scaling
Huge p/ at =3.2
& breaking
Two particle correlation
Near side
Ridge
dAu
RCP
decrease with 
data
Away side
Jet
Double bump
Three particle correlation
(1 or 2 triggers)
Auto-correlation
(no trigger)
3
Overview
Single particle distribution

pT
B/M ~ 1
p

RCP
 RCP
,
CP
R
K ,
CP
R
v2  ET 
nq  nq 

universal
(dAu) quark number scaling
Huge p/ at =3.2
& breaking
Two particle correlation
Near side
Ridge
dAu
RCP
decrease with 
data
Away side
Jet
Double bump
Three particle correlation
(1 or 2 triggers)
Auto-correlation
(no trigger)
4

u, d, s
Recombination
at
g converted to q
Intermediate pT
c,b,t primordial
J
partons
What partons?
hadrons
Medium effects
5
pT
Baryon/Meson ratios
STAR
4
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
/K
3
2
1
0
in recombination/coalescence model (Reco)
“Baryon anomaly” implies that fragmentation is normal.
On the contrary, high B/M ratio is a signature of Reco.
Baryons need less quark momenta than mesons.
6

Elliptic flow
M: TT + TS + SS
B: TTT + TTS + TSS + SSS
v2M ( pT )  v2T q1   v2T q2  v2B ( pT )  v2T q1   v2T q2   v2T q3 
M
B
q

q

p
/
2
v
p
v
M:
2  T 
2  pT 
1
2
T
then
If
  ;
 
2
2
3
3
B: q1  q2  q3  pT / 3
pT  KET
0.1
v2 / nq
0.05
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
quark number scaling
(QNS)
Molnar & Voloshin, PRL91,(2003)
a property of naïve
recombination
7
However, at larger KET
M: TT + TS + SS
B: TTT + TTS + TSS + SSS
v2M ( pT )  v2T q1   v2S q2  v2B ( pT )  v2T q1   v2T q2   v2S q3 
q1  q2
v2T  v2S
v2M  pT  v2B  pT 
    
2 2
3 3
QNS is broken,
but hadronization is
still by recombination
STAR, PRC75,054906(07)

p
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
K

minbias
8
RH&CBY,0801.2183

Forward production
Au+Au at 62.4 GeV
BRAHMS, nucl-ex/0602018
xF = 0.9
xF = 1.0
xF = 0.8
Shower partons are
suppressed at the
kinematical boundary
Few antiquarks
at large 
TS
TTT
TT
mainly p produced
9
BRAHMS
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
(preliminary)
Comments at the end, if asked.
10
Correlation on the near side
ridge R
Jet
J
Ridgeology
J+R
STAR

R


Putschke, QM06
J

Properties of Ridge Yield
Dependences on Npart, pT,trig, pT,assoc, trigger 
B/M ratio in the ridge
11
1.
2. on pT,trig
Dependence on Npart
STAR preliminary
Jet+Ridge ()
Jet ()
pt,assoc. > 2 GeV
Putschke,
QM06
Jet)
R
Ridge yield
0
as Npart
0
 depends on medium
Ridges observed at any pT,trig
Ridge is correlated to jet production.
Surface bias of jet  ridge is due to
medium effect near the surface
Medium effect near surface
12
3.
Dependence on trigger 
STAR (preliminary)
A. Feng
T
s
RP
20-60%, 3-4:1.5-2
|  1
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Comments at the end,
if
asked.
Ridge yield decreases
with increasing s
Mismatch of T and
the direction of
radial expansion.
has more
ridge yield
than
Ridge develops by radial
flow near the jet axis
13
4. Dependence on pT,assoc
Putschke, QM06
STAR
Ridge
Ridge is exponential
in pT,assoc
slope
independent of pT,trig
Exponential behavior
implies thermal source.
Yet Ridge is correlated to jet
production; thermal does not
mean no correlation.
Ridge is from thermal source enhanced
by energy loss by semi-hard partons
traversing the medium.
14
5.
B/M ratio in the ridge
pt,assoc. > 2 GeV
p
STAR
Putschke, QM06
Bielcikova,
WWND07
+
Au+Au 0-10%

p(R) / p(J )
 (R) /  (J )
K

: 2
K
 2-4
Large B/M
Ridge hadrons are
formed by recombination
15
Medium effect
near surface
coordinated
with radial flow
Ridge is from enhanced
thermal source caused
by semi-hard scattering.
SS
trigger
peak (J)
Recombination of
partons in the ridge
associated
particles
ST
TT ridge (R)

But of interest below is
mainly the  distribution.
These wings are
useful to identify
the Ridge

16
What are the consequences of
Ridgeology?
1. Jet correlation at low and intermediate pT
2. Effect on single particle spectra
3. Effect on elliptic flow
17
1. Jet correlation at intermediate pT
PHENIX, PLB 649,359(07)
PHENIX
||<0.35
Does not see the ridge
Peak is referred
to as jet
J
R
Correlation in J
is different from
correlation in R
Not seeing the ridge does
not mean that it is not there.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
2.5<pT,trig<4 GeV/c
1.8<pT,assoc<2.5
18
PHENIX, PLB 649,359(07)
Jet + Ridge
STAR preliminary
TT
Jet
Not un-correlated. Ridge
would not be there without
STAR preliminary
semi-hard
scattering.
SS
TS
0.35
How can intermediate-pt Jet yield
be independent of centrality?
19
STAR
PHENIX 0712.3033
pt,assoc. > 2 GeV
p
Au+Au 0-10%
2
1
R
Putschke, QM06

J
2.5<pT,trig<4.0 GeV/c
p(R) / p(J )
 (R) /  (J )
PHENIX data cannot be
properly understood without
taking Ridge into account
2
20
2. Effect of Ridge on single-particle spectra
Semi-hard scattering at kT~2-3 GeV/c is pervasive.
Auto-correlation
without triggers.
0.15<pt<2.0 GeV/c, ||<1.3,
at 130 GeV
STAR, PRC 73, 064907 (2006)
Ridges are present
with or without triggers.
21
TT
TS
(fragmentation)
SS
Bulk+
Ridge
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Semi-hard partons
generating ridge
Fragments from
hard partons
T includes enhanced thermal
partons --- Ridge
22
How can we see better the TT component?
Remove the TS and SS components, if possible.
 production:
Au+Au   + anything
dN/ptdpt (log scale)
(sss) s quark suppressed in shower
Exposes the long
exponential behavior
in  production
TTT
TTS
uud
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
sss
pt
23
 spectrum is exponential (thermal)
STAR
How can it have correlated
partners? --- the  puzzle.
R only
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Resolution:
Both  and its associated
hadrons are in the Ridge.
Prediction: there is no peak (J)
in the  distribution --- only R
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Chiu & Hwa,
PRC76,024904
(2007)
24
3. Effect of Ridge on elliptic flow
Initial configuration


A semi-hard scattering near
the surface gives rise to a jet,
whose direction, on average,
is normal to the surface.
If the semi-hard jets are soft enough,
there are many of them, all restricted
to || < .
 = cos-1(b/2R)
There is a layer of ridges at the
surface without triggers.
25
In momentum space
dN
 B( pT )  R( pT )( )
pT dpT d
B
bow tie region
B+R
sin 2(b)
v2 ( pT )  cos 2 
 B( pT ) / R( pT )  2(b)
Use data on B(pT) and R(pT)
Relate ridgeology to v2
Hwa, 0708.1508
26
Elliptic flow at low pT
v2 driven by Ridge
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Made no assumption about rapid thermalization.27
Elliptic flow at intermediate pT
v2 dominated by TS recombination
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
Hwa & CB Yang, 0801.2183
28
STAR, PRL 95, 152301 (05)
Away-side correlation
Double-bump first observed by STAR
has been studied extensively --experimentally and theoretically.
PHENIX 0705.3238 & .3060
Mach cone
gluon
radiation
Cherenkov
radiation deflected
2D
mild dependence
of D on pt,assoc
favors
Is there any connection
between the double bumps
and ridge w/o peak(J)?29
Possible relationship between ridge and bump (Renk, Jia)
Near side
Ridge
Generated by semi-hard
scattering
Exponential pt,assoc
Large B/M ratio
Due to recombination of
enhanced thermal partons
Away side
Bump
Mach cone, deflected jet,--due to recoil of semi-hard parton
Distribution in pt,assoc ?
B/M ratio is also large.
What is partonic structure
of the Mach-shock-wave?
30
Papers submitted to the session on:
“Response of Medium to Jets”
Experimental
Netrakanti
Wenger
McCumber
Suarez
Feng
Adare
Barannikova
Catu
Daugherity
Pei
Haag
Szuba
G. Ma
Wang
Noferini
Chetluru
(STAR)
(PHOBOS)
(PHENIX)
(STAR)
(STAR)
(PHENIX)
(STAR)
(STAR)
(STAR)
(PHENIX)
(STAR)
(NA49)
(STAR)
(STAR)
(ALICE)
(UIC)
Theoretical
Majumder
C.Y.Wong
Gavin
Mizukawa, Hirano, Isse, Nara, Ohnishi
Pantuev
Lokhtin, Petrushanko, Snigirev, Sarycheva
Levai, Barnafoldi, Fai
Betz, Gyulassy, Rischke, Stoecker, Torrieri
Molnar
Asakawa, Mueller, Neufeld, Nonaka, Puppert
Schenke, Dumitru, Nara, Strickland
Bauchle
Plenary session X
Ulery
Jia
31
On to LHC
Many predictions made (see arXiv:0711.0974)
Those with existing codes can make extrapolations.
Eskola et al (EKRT model)
Is there new physics that cannot
be obtained by extrapolation?
hard parton
energy
loss
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
SS
hadron
Density of semi-hard partons is high at LHC.
SS or SSS recombination to form  or p.
S
S
semi-hard partons
p/>>1
32
What is the bulk background at LHC?
Since SS and SSS recombination of semi-hard partons
are uncorrelated, they occur in mixed events.
Thus they belong to the background.
But those partons are not thermal,  not in hydro.
So there is a mismatch between bg and hydro.
Can Ridge be identified in association with a high pT trigger
--- pT,trig > 20 GeV/c?
The ridge may not stand out among the background
that consists of TT, TS, SS, TTT, TTS, TSS, SSS hadrons.
Physics at intermediate pT at LHC may be
very different from that at RHIC ----cannot be obtained by extrapolation.
33
Summary
Physics revealed by phenomena
observed at intermediate pT

soft &
semi-hard
partons
J
34
Large B/M
ratio
v2
QN scaling
and breaking
T
S
Ridge
Jet
Exponential
pT at large 
Reco at
LHC
Double
bump
35
Backup slides
36
Forward production
At large xF, proton can be formed by leading quarks from different nucleons.
 3 dxi  u
u
d
F
(x
)F
(x
)F
(x3 )Rp (x1, x2 , x3 , x)


1

2

  x 
i 1
i
p
x can exceed 1
momenta degraded
 survival probability
Pions are suppressed
due to the lack of
antiquarks at large xi.

~0.75
QuickTime™ and a
TIFF (LZW) decompressor
are needed to see this picture.
BRAHMS (preliminary)
“baryon stopping”
Antiquarks at low xi are
affected by the regeneration
of qq that depends on .
Hwa & CBYang, PRC76,104901(2007)
 should be larger
less degradation
more protons
less increase of pions
larger p/ ratio
37
3.
Dependence on trigger 
STAR (preliminary)
A. Feng
T
s
RP
20-60%, 3-4:1.5-2
|  1
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Ridge yield decreases
with increasing s
Mismatch of T and
the direction of
radial expansion.
has more
ridge yield
than
Ridge develops by radial
flow near the jet axis
38