1 The sQGP at RHIC: Recent Results and New Possibilities Richard Seto University of California,...
-
date post
19-Dec-2015 -
Category
Documents
-
view
216 -
download
0
Transcript of 1 The sQGP at RHIC: Recent Results and New Possibilities Richard Seto University of California,...
1
The sQGP at RHIC: Recent Results and New
Possibilities
Richard SetoUniversity of California, Riverside
Jyvaskyla, Finland April 28, 2006
2
What we know: RHIC What we know
System appears thermally and chemically equilibrated This happens early <2 fm/c
Energy density high >10 GeV/fm3
parton energy loss is large viscosity/entropy, η/s is low ( conjecture ~1/4π?) DOF ~ “quasi-quarks”
General picture is stable since ~ 2004 More data since QM 2005 More theory A clearer view
Properties of Medium
3
Busy days at RHIC
4 experiments – BRAHMS, PHENIX, PHOBOS, STAR
p+p d+Au Au+Au Cu+Cu
200 GeV
130 GeV
62.4 GeV
22.4 GeV
Run 1 - 3 Run 4 - 5 Run 6
?
4
A cartoon – the life history of the sQGP
0.1 1
0.1
~Energ
y
Densi
ty
(GeV
/fm
3)
10~Time (fm)
10
100
L. McLerran
(modified by R.S.)
Elliptic flow
Cross over(wanna be1st order)4
5
CGC “glasma” T. Lappi
Strongly Interacting
Recombination
~some reinteraction
Thermalization
hard probes
Partonic
5
energy density“jet” energy loss
hardprobles
energyloss
6
What is the energy density? “Jet quenching”
direct photons scale as Ncoll π0 suppressed
hadron suppression shows quenching independent of identity of produced hadron
AuAu 200 GeV
RAA
Calculations:dNg/dy ~ 1000Wicks et al, nucl-th/0512076
ε ~10-15 GeV/fm3
ε critial ~0.6 GeV/fm3
Direct γ
π0
η
7
System dependenceAu+Au and Cu+Cu sNN = 200 GeV
8
Au+Au and Cu+Cu sNN = 200 GeV
RAA Function of Npart independent of system
9
light
(M.Djordjevic PRL 94 (2004))
How is the energy lost? The sQGP has enormous stopping power
rifle bullet stopped in a tissue Original idea – energy loss by gluon radiation In 2001, Dokshitzer and Kharzeev showed “dead
cone” effect charm quark small energy loss
10
(3) q_hat = 14 GeV2/fm
(2) q_hat = 4 GeV2/fm
(1) q_hat = 0 GeV2/fm
(4) dNg /dy = 1000
Theory curves (1-3) from N. Armesto, et al., PRD 71, 054027
(4) from M. Djordjevic, M. Gyullasy, S.Wicks, PRL 94, 112301
What about heavy quarks? (electrons from c and b)
Charm high pT suppression is as strong as light hadrons!!!
Problem – difficult to reconcile with gluon radiative energy loss
theorists have to go back to the drawing board
11
Hadronization(so I can introduce recombination)
reco
12
Recombination and the baryon anomaly pbar/π varies with √sNN in Cu+Cu
PHENIX PreliminaryOriginally thought:
particle production at “moderate” pTfrom mini-jet Fragmentation pbar/π- ratio
CuCu central
At ISR pbar/π- ~ 0.2
Heavy ion Collisions pbar/π- ~0.7Increasing with energy
BUT
200 GeV
22 GeV
higher energy
13
Baryon/meson (pbar/-) at √s = 200 GeV AuAu
• Scales with Npart independent of system at h=0 and 3.2
14
Explanation: Recombination
Naively: recombine quasi-partons (“quasiquarks” – Gavai)
PT baryons pT 3 pT
mesons pT 2 pT
Problem: protons exhibit “jettiness”
+ Thermal spectrum = Large pbar/π
This implies that we begin in a “quasi-partonic” thermal system
Mueller et al, Hwa et al, Ko et al
15
ReCo Model Modification (Hwa)
Premise:
Observables:
STAR Preliminary
STAR P
relim
inar
yThe production of Φ and
Ω particles is almost exclusively from thermal strange quarks even out
to 8 GeV/c
The ratio of Ω/Φ yields should rise linearly with pT
16
Elliptic Flow (v2)Viscosity
Recombination
v2
v2
17
Previous Results
If system free streams spatial anisotropy is lost v2 is not developed
Hence Early thermalization low viscosity
PHENIXHuovinen et al
(Teany et al, Huovinen et al)
detailed hydro calculations (QGP+mixed+RG, zero viscosity) εtherm ~ 0.6 -1.0 fm/c ε~15-25 GeV/fm3
(ref: cold matter 0.16 GeV/fm3)
18
Recombination and v2
1) Three regions of v2
geometry-driven momentum anisotropy
geometry-driven absorption anisotropy
STAR preliminary
from partonicAND hadronicmassmass dependent dependent
from partonicquarkquark number dependent number dependent
Maya Shimomura, SQM’06
v2
v2
19
PHENIX Preliminary
2) Data from minimum bias Au+Au collisions at sNN= 200 GeV
(mT - m0)
20
PHENIX Preliminary
3) A recombination testrescale by quark number Au+Au collisions at √sNN= 200 GeV
(mT - m0)Recombinationworks!
21
v2 of strange hadrons from STARPHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)
• Mass ordering observed at lower pT fit by hydro in hadronic phase
• v2 saturates for pT > 3 GeV/c
• Clear baryon/meson difference at intermediate to high pT
observed
• New, high statistics measurement shows deviation from ideal scaling • Mesons > 1
• Baryons<1
• Consistent with gluon-quark constituent models of recombination
22PHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)
v2 of strange hadrons from STAR
• Mass ordering observed at lower pT fit by hydro in hadronic phase
• v2 saturates for pT > 3 GeV/c
• Clear baryon/meson difference at intermediate to high pT
observed
• New, high statistics measurement shows deviation from ideal scaling • Mesons > 1
• Baryons<1
• Consistent with gluon-quark constituent models of recombination
23
The same scaling behaviour is observed in 62 GeV data
v2 of strange hadrons from STAR
PHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)
Au+Au ĆsNN=62 GeV
STAR Preliminary• Mass ordering observed
at lower pT fit by hydro in hadronic phase
• v2 saturates for pT > 3 GeV/c
• Clear baryon/meson difference at intermediate to high pT
observed• New, high statistics
measurement shows deviation from ideal scaling
• Mesons > 1• Baryons<1• Consistent with gluon-
quark constituent models of recombination
24
The - a test the
mass ~ proton quarks - meson
V2 behaves as recombinationsays it should
ALL hadrons seem to obey quark number scaling!
25
Hydro works in min-bias not as function of centrality
initial cond? (Rafelski)
Hydrodynamics (in the hadronic phase) and centrality
26
Recombination and centrality?
recombination and number of quark scaling works for centrality dependence
mid-centralperipheral central
Recombination works well. WHY?What is recombining?? DOF???A quasi-quark Plasma? “constituent quarks”
27
different degrees of freedom introduce different correlations between conserved charges
• assumption: conservation of charge @ hadronization local in rapidity
• introduce baryon-number strangeness correlation:
• system of particles:
• connection to Lattice susceptibilities:
DOF and Baryon-Strangeness Correlations
2 223 3BS
BS B S BSC
SS S
23 k k kk
BSk kk
n B SC
n S
3 BSBS
SS
C
QP-QGP: CBS=1
HG: CBS~ 2/3
BS-QGP: CBS~0.61
CBS: V. Koch, A. Majumder & J. Randrup, PRL95 182301 (2005)
BS-QGP: E. Shuryak, I. Zahed, PRC70 021901 (2004); PRD70 054507 (2004)
28
CBS & CQS: Lattice & Lessons
Gavai & Gupta, PRD 73, 14006, 2006
T>TC: CBS=1
• mesonic as well as baryonic bound-states ruled out via χBS
Lattice confirms quasi-quark nature of flavor carriers in the deconfined phase
Gavai, Majumder
29
v2 heavy quarks and viscosity
The stone in the river
or the concrete canoe
University of Wisconsin Badgers engineer third-straight concrete canoe title
30
Flow, viscosity, and strong coupling Conversion of spatial anisotropy to
momentum anisotropy depends on viscosity Same phenomena observed in gases of
strongly interacting atoms (Li6)
weakly coupledfinite
viscosity
strongly coupled
viscosity~0
The RHIC fluid behaves like this, viscocity~0
M. Gehm, et alScience 298 2179 (2002)
now throw a stone in there
31
Heavy quarks: Single electron v2
data prefers charm flow
for charm to flow interactions must be very strong
Viscosity small
Greco, Ko, Rapp PLB 595 (2004) 202
32
B meson contribution heavy quark electron v2
B electron v2 reduces heavy quark electron v2 @ high pT
We need to directly measure D’s and B’s
pT
based on quark coalescence model c, b reso ; c,b get v2 by elastic scat. in QGP
Hendrik, Greco, Rappnucl-th/0508055 w.o. B meson (c flow)
w. B meson (c,b flow)
33
Comment on a quantitative measure of the viscosity
Upgrades -microvertex detectors - to both STAR and PHENIX will allow measurement of D and B mesons directly
Theory – will take a while
Meanwhile – viscosity better become part of our ethos
34
Back to the beginningHow does the sQGP get started?
a candidate - the CGC
CGC
35
prediction: suppression in dAu collisions forward central
Central Midcentral
CGC
for all particles
36
What about charm? prompt muons charm(bottom) are suppressed in
dAu CGC
Xiaorong Wang, SQM 2006
Aud
Au d
North Arm
South Arm
37
Initial Temperature
Tinitial
38
Thermal photons - The Spectrum
Compare to thermal + pQCD• data consistent with
thermal + pQCD
Compare to thermal model
• data above thermal at high pT
• D. d’Enterria, D. Perresounko• nucl-th/0503054
Compare to NLO pQCD
• excess above pQCD
• L.E.Gordon and W. Vogelsang• Phys. Rev. D48, 3136 (1993)
2+1 hydro
T0ave=360 MeV(T0
max=570 MeV)
t0=0.15 fm/c
The Future – PHENIX- HBD
39
What have we learned Jet quenching
Charm quark energy loss, pretty well established Viscosity
Charm flows – further evidence that viscosity is small (interactions are strong)
Recombination baryon to meson ratio seems to obey recombination scaling All particles seem seem to obey v2 recombination scaling. [, ;Ω]
Some evidence for fine structure Evidence for quasi-partons from Recombination/Lattice
CGC indications of charm suppression in dAu collisions at forward rapidity
RHIC is now studying a state of matter clearly above the transitionQuestion: So where is it? Deconfinement? Is there a critical point?
40
Deconfinement and Screening (a puzzle)
Debyescreening
41
A Theory update which bothers experimentalists
J/ “melts” at T>1.5 TC (Agnes Mocsy, Peter Petereczky)
“Screening likely not responsible for quarkonia suppression” (Agnes Mocsy, Peter Petereczky)
“You have to use the right potential” (CY Wong)
Does quarkonia suppression tell us anything about deconfinement!???
Who is right?!!
an experimentalist
42
J/ suppression Suppression
similar in amount to SPS
consistent with screening+ regeneration
screening
regeneration
sum
43
|y|<0.35 1.2<|y|<2.4
Aside: RAA of J/ in Au+Au/Cu+Cu
Constrained by d+Au
Most things depend on Npart independent of species Why is J/ at y=0 different for Cu and Au? Corona? Might help in understanding suppression mechanism
CuCu
AuAu
44
<pT2> as a function of Ncol
Au+Au = RED
Cu+Cu = BLUE
Dashed: without recombination
Solid: includes recombination
Recombination modelmatches better to the data...
nucl-th/0505055
45
Recombination predictions vs rapidity
Recombination ( Thews et al., nucl-th/0505055 ) predicts a narrower rapidity distribution with an increasing Npart.
Going from p+p to the most central Au+Au : no significant change seen in the shape of the rapidity distribution.
No recombinationAll recombination
Central
peripheral
46
RAA vs. pT in Au+Au/Cu+Cu
•Suppression of J/ψ yield at low pT in both Au+Au and Cu+Cu.•High pT J/ψ escape the medium? Leakage effect? [Phys. Lett. B 607 (2005)]
•Might one expect “pile up” at low pT for recombination+energy loss?
47
Questions What is the energy loss mechanism for hard quarks? Can we get a good measure of the initial temperature? Chiral Symmetry? Deconfinement? Any Clue? Is the CGC really the initial state for the sQGP Can we measure quantitatively the viscosity?
THEORY
More General Questions Do we understand why the interaction is so strong? Do we understand the DOF?
Interplay of theory and experiment – very important
both in the “CGC” and the “sQGP”
48
The FutureRHIC II RHIC II
increase in LuminosityHigh L at lower energies- the critical point
PHENIX- upgradesPHENIX- upgradesThe Nosecone Calorimeter
49
What would we like to measure?
50
What would we like to measure? What is the energy loss mechanism for hard quarks?
Jet tomography (high pT PID, jet-jet and -jet) Can we get a good measure of the initial temperature? Chiral Symmetry?
Electromagnetic radiation (e+epair continuum, LMVM) Deconfinement? Any Clue?
Quarkonium (J/, ’ , c and (1s),(2s),(3s)) Is the CGC really the initial state for the sQGP
gluon saturation in nuclei (particle production at forward rapidity)
Can we measure quantitatively the viscosity? Heavy flavor (c- and b-production)
What is the energy loss mechanism for hard quarks? Jet tomography (high pT PID, jet-jet and -jet)
Can we get a good measure of the initial temperature? Chiral Symmetry?
Electromagnetic radiation (e+epair continuum, LMVM) Deconfinement? Any Clue?
Quarkonium (J/, ’ , c and (1s),(2s),(3s)) Is the CGC really the initial state for the sQGP
gluon saturation in nuclei (particle production at forward rapidity)
Can we measure quantitatively the viscosity? Heavy flavor (c- and b-production)
requires highestAA luminosity
51
Dalitz/conversion rejection (HBD) Precision vertex tracking (VTX)
PID (k,p,p) to 10 GeV (Aerogel/TOF)
High rate trigger (μ trigger) Precision vertex tracking (FVTX)
Electron and photon measurements Muon arm acceptance (NCC) Very forward (MPC)
PHENIX Detector Upgrades at a Glance Central arms:
Electron and Photon measurements Electromagnetic calorimeter Precision momentum determination
Hadron identification
Muon arms: Muon
Identification Momentum determination
52
HBD
VTX
NCC
PHENIX Upgrades in Central Region
Vertex Tracking (barrel and forward endcaps)
Precision measurements of charm and bottom production
Hadron blind detector (HBD) Reject Dalitz/Conversion electrons
in electron pair measurement trigger
W measurements in pp
Nose Cone Calorimeter0 and photon measurements
R3……...R2………..R1
53
2006 2007 2008 2009 2010 2011 2012
x4 Lum
RHIC II
HBD
VTX-barrel
VTX-endcap
NCCNCCMuTrigger
DAQ
R&D Phase Construction Phase Ready for Data
PHENIX/RHIC Upgrades Schedule
54
Connecting to lower energies unique things (so far)
ρ broadening break in Inverse
slopes @ √sNN~5
AGS/SPS/RHIC similarities strangeness
enhancement J/psi suppression
Ways to look wait for GSI wait for JPARK RHIC ~ 5GeV
Survival probability corrected for normal absorption
energy density
Karsch, Kharzeev, Satz
55
Think Carefully Varying beam energy
varies energy density – not T Looking for a sharp
“step” probably will not work at least not in T
But we also vary ρBaryon
Could we find the Critical point?
Rare probes e.g. leptons???
T/Tc
ε/T4T/Tc
1
ε
critical point?
56
RHIC II-electron cooling (Roser) x10 increase in L
over x4 from design No apparent show-stoppers
for RHIC collisions at Ecm = 5-50 GeV/n AuAu
Pre-cooling in AGS 10x luminosity ?
Electron beam cooling would make this a fantastic facility: ~100x luminosity,
Exp
ecte
d Z
DC
(w
hole
vert
ex M
B)
Rate
[H
z]
Possible increase in luminosityfor lower energiesx1000?
AGSequivalent
CERNequivalent
assume x100
PresentFullEnergy
57
The Nosecone Calorimeter
or
What I am really doing in Finland
58
The PHENIX central EMCAL
The central EMCAL has been one of the most important subdetectors in PHENIX
done with a calorimeter -0.35<η<0.35 and ½ of 2π
ε~ 10-15 GeV/fm3
/1
/TAA
AATbinary pp
dN dpR
N dN dp
AuAu
dAu
π 0
59
What is proposed?the NoseCone Calorimeter
NCC NCC
-3 -2 -1 0 1 2 3 η
0
cove
rage
2π
EMC
EMC
ηη coverage from 1 to 3 coverage from 1 to 3RHIC II – luminosity x10 RHIC II – luminosity x10 PHENIX acceptance x10PHENIX acceptance x10
Precision measurements possiblePrecision measurements possible
Note: DOE-1st NCC, collabor- 2nd NCC
VTX & FVTX
near full coverage for tracking and calorimetrynear full coverage for tracking and calorimetry
60
•What is the Physics I? QCD: Heavy Ion Physics and the sQGP
Heavy Ions Getting a picture of collision system
This is why the CAT scan so important. STM. Energy density (tomography) changes with rapidity large
rapidity coverage Calibrated probe: photon-jets – need large acceptance
Understanding deconfinement, Tc Recently lattice: J/ψ melts at >Tc
χcγJ/ψ – must go to forward rapidity probably the only detector capable of doing this at RHIC
jetE E γ
Leading hadronsπ0
61
What is the Physics II? QCD: Proton Nucleus Physics and the Colored Glass Condensate
More saturation at Lower x y~log(1/x) Lower x forward rapidity
xG(x)
x
measure gluon saturationvia direct photonsin forward region
The Colored Glass Condensate:The Initial Condition for HeavyIon Collisions?
Low
er
x
62
What is the Physics III?QCD: polarized pp collisions and the Spin of the Proton
Where is the spin of the proton? Idea: Measure the gluon spin contribution ΔG ΔG may be dominated by contributions from low-x
where gluons are most abundant y~log(1/x) So low x is forward rapidity
e.g. y~2 for x=10-2
Go to Forward RapidityxG(x)
x
63
Where is it?
Edouard/Andrey
NCC 0.9 < h < 3.0
HBD
NCC
VTX
NCC
64
What is it? The parts of the NCC
Silicon pads1.5x1.5 cm2
Tungsten 3 mm (EM) & 15mm (HAD)
500 um pitch Strips (“StriPixels”)
EM1electromagnetic
EM2electromagnetic
HADhadron identifier
SM“shower max”
PS“pre-shower”
18%4%
E
E E
Depth: 42X0 (1.6 λABS)
65
Silicon pads1.5x1.5 cm2
Tungsten 3 mm (EM) & 15mm (HAD)
HADhadron identifier
SM“shower max”
PS“pre-shower”
18%4%
E
E E
Depth: 42X0 (1.6λABS)
30 GeV π0
The PS and SMDetectors:
identifying π0s
500 um pitch Strips (“StriPixels”)
SM
What is it? The parts of the NCC
66
What has the NCC crew accomplished?Prototype in Test Beam at Protvino
Edouard
σ = 10%
10 GeV electron
67
How Much and When?Schedule and cost Scope of proposal to DOE:
1 NCC ~ $4M Begin Funding in FY2008 All Critical physics can be done with 1 NCC
Complete Construction in 2010 Reviewed my external committee
recommend start of funding FY 2008 in less than 18 months!
68
NCC - 2 Build second NCC from Collaboration funds
Actively seeking funds from International Collaborators
Japan, Korea, Russia, Czech Republic, …
Added Benefits: Factor ×2 in rate for rare processes Exploit muon spectrometer acceptance in pA collisions, can study both sides simultaneously
69
Come join us!