Rapporteur 3

1
Rapporteur 3 Bulk Properties and Collective
Phenomena ShinIchi Esumi Univ. of
Tsukuba
2
dn/dy, spectra, chemical/thermal
freeze-out stopping, radial flow,
recombination HBT, global polarization rapidity
dependence eccentricity definition event by
event v2 fluctuation v1 and v2 scaling jet and
its correlation with v2 charm quark interaction
and collectivity direct photon as a probe of bulk
matter
3
baryon transport (stopping)
AGS
NA49 preliminary
SPS
RHIC 62
net proton dN/dy
(BRAHMS preliminary)
RHIC 200
LHC 5500
4
hadron spectra after strong radial expansion
STAR Preliminary
STAR Preliminary
5
hadron production at chemical freeze-out close to
the phase boundary
BRAHMS
BRAHMS
6
baryon transport radial flow recombination
jet suppression
p/?
AuAu 200GeV STAR preliminary
7
HBT freeze-out is given by energy density.
strong effect from collective expansion and
space-time correlation. reconstruct source image
without assuming the source shape
8
global polarization Lambda polarization w.r.t.
(normal to) directed event plane no significant
signal observed, upper limit PL,L10-2
9
rapidity dependence of identified particle
nuclear suppression
y0
y1
y3.1
pions
kaons
protons
No strong indication of rapidity dependence
10
rapidity dependence of identified particle v2
?0
?3
BRAHMS preliminary
?
K
p
No strong indication of rapidity dependence, the
strong rapidity dependence on the integrated v2
is more or less explained by the mean pT.
Meson/baryon splitting might be different between
y0 and y3, if statistical significance is
improved.
11
eccentricity definition
Standard Eccentricity
Participant Eccentricity
200 GeV
200 GeV
CuCu
CuCu
AuAu
AuAu
arXivnucl-ex/0610037, submitted to PRL
12
v2 scales with ltepartgt and energy
densidy
13
event by event v2 fluctuation vs epart fluctuation
PHOBOS epart prediction
This relative v2 fluctuation can be explained by
initial epart fluctuation
MC with nofluctuations
14
eccentricity re-visited
(1) exclude one participant to define a new
frame (2) calculate position of the excluded
participant in the new frame (3) repeat above 2
steps for all participants (4) get eccentricity
using positions of all participants Each
participant position is defined in its own frame.
If particles are generated from position of
participants, it is more natural to get
eccentricity in this way. I would not say this is
the best, just like to say there is still a room
for improvements.
All participant positions are used to define a
new axis and to get eccentricity simultaneously
in the new rotated axis. We try to remove a
particle from reaction plane definition to avoid
auto-correlation between particle and event
plane, when measuring v2 of the particle.
eSTD
ePART
eMOD
e
e
CuCu
AuAu
y (fm)
Participant Modified Standard
x (fm)
e
impact parameter b (fm)
impact parameter b (fm)
15
centrality dependence of v2 comparison of v2
ratio CuCu/AuAu (gt1) at central (lt10)
collisions between experiments
STAR
PHENIX PRELIMINARY
epart 0-5 1.5/0.9 1.7
5-10 1.7/1.1 1.5 experiment
Cu/Au v2 ratio phobos
2.6/1.5 1.7
3.1/2.1 1.5 star v220-5 3.7/2.5
1.5 5-10 4.2/3.5
1.2 star v2ftpc 0-5 3.0/2.1 1.4
5-10 3.4/3.4 1.0 phenix 0-10
4.0/3.0 1.3
16
V22 V2FTPC - V24
V2BBC R.P.
PHENIX 200GeV AuAu 30-40
STAR 200GeV AuAu 20-60
PHOBOS 200GeV AuAu 20-40
STAR FTPC and PHENIX BBC have about same
acceptance.
V22 V2FTPC V2AA-pp
STAR 200GeV CuCu 20-60
PHOBOS 200GeV CuCu 20-40
PHENIX 200GeV CuCu
17
v1 scaling w.r.t. beam rapidity and v1 wiggle
(proton)
STAR preliminary
Centrality scaling for v1 seems to work better
than participant scaling which works for the most
of other global variables. This might be trivial
if this is only given by participant/spectator
shape alone not by the size at all
spectator v1 direction
Different trend could be caused by the different
pT cut off.
anti-flow of p as seen in SPS
STAR preliminary
PHOBOS
18
v2 scaling with mT-m number of quark (same as
hydro at low pT number of quark)
When the mass effect removed by mT-m, only the
quark number ratio shows up! Is mass ordering of
v2 at low pT generated during or after
hadronization? Feed-down for pion is visible in
pT, but not in mT-m, because pT(daughter) lt
pT(parent) , but mT-m(daughter) mT-m(parent)
Decay kinematical effect is masked by the pT to
mT-m transformation.
19
v2 scaling with mT-m number of quark
Early freeze-out effect of multi-strangeness
hadrons seen in spectra analysis with radial flow
does not show up here in v2 analysis, this is an
indication that v2 is already built up in early
stage.
Number of quark scaling is not only the
explanation.
RQMD AuAu 200GeV
Feng Liu
v2
pT (GeV/c)
20
jet modification and cone like structure
STAR preliminary
0-5 Pb Au 17GeV pTtrig2.5-4 GeV/c
pTassoc1-2.5 GeV/c
PHENIX nucl-ex/0611019
CERES preliminary
0-12 200 GeV AuAu
PHENIX Preliminary 10-20 AuAu
200GeV pTtrig2.5-4 GeV/c pTassoc1-2.5 GeV/c
STAR preliminary 0-12 AuAu 200GeV pTtrig3-4
GeV/c pTassoc1-2 GeV/c
CERES preliminary0-5 Pb Au 17GeV pTtrig2.5-4
GeV/c pTassoc1-2.5 GeV/c
The bulk and jet interaction is there, but in
CuCu/AuAu and SPS-RHIC?!?
21
jet modification and its correlation with v2
jet shape w.r.t. reaction plane geometrical
effect of the almond shape This effect itself is
a one of v2 sources, which will be an important
effect at LHC. This should also lead different v2
between bulk and jet.
22
charm quark suppression and flow
Charm quark interaction in bulk matter, this
makes suppression and collectivity of charm
quarks as well as light quarks.
23
more hints of charm quark collectivity
N. Xu, SQM 2006, PHENIX (?, K, p, J/?) PRC69,
034909(04), QM05 STAR (?, ?, ?) QM05
PBM et. al. QM06
RHIC
SPS
SPS
J/y would need re-generation, both J/y and open
charm spectra are consistent with small
transverse radial flow, which might be built up
during partonic stage
24
direct photon as a probe of bulk matter
Jet-frag. photon from the survived parton v2 gt 0
thermal photon v2 gt 0
prompt photon v2 0
v2 lt 0
Inclusive photon v2 presented by STAR
consistent with prompt photon production, but we
are allowed to speculate, I guess
PHENIX preliminary
We just have installed a new reaction plane
detector for coming high luminosity AuAu run7
for rare probe v2 measurement at PHENIX.
25
Summary Large number of variables indicate as if
there is Quark Gluon Plasma formed at RHIC
energies or maybe already at lower energies,
however the most of the evidences are still only
suggestive, can we look for more direct evidence?