Transcript High T QCD at RHIC: Hard Probes Axel Drees, Stony Brook University Rutgers NJ, January 12 2006 Fundamental open questions for high T.

High T QCD at RHIC: Hard Probes
Axel Drees, Stony Brook University
Rutgers NJ, January 12 2006
Fundamental open questions for high T QCD
Nature of matter created at RHIC
Critical Point
Hadronization
Rapid thermalization
Experimental quest for answers
Status of key experimental probes
limitations of progress and solutions with upgrades of RHIC
Ongoing and planed improvements to RHIC
Time line, detector and accelerator upgrades (RHIC II)
Summary
Study high T and r QCD in the Laboratory
Quark Matter: Many new phases
of matter
Exploring the Phase Diagram of QCD
T
Asymptotically free quarks &
gluons
Strongly coupled plasma
Superconductors, CFL ….
Quark Matter
Mostly uncharted territory
sQGP
TC~170 MeV
Experimental access to “high” T
and moderate r region: heavy ion
collisions
Pioneered at AGS and SPS
Ongoing program at RHIC
Hadron
Resonance Gas
Overwhelming evidence:
Strongly coupled quark matter
produced at RHIC
Nuclear
Matter
baryon chemical potential
940 MeV
1200-1700 MeV
mB
Axel Drees
Quark Matter Produced at RHIC
III. Jet Quenching
I. Transverse Energy
PHENIX
130 GeV
Bjorken estimate:
t0 ~ 0.3 fm
dNg/dy ~ 1100
V2
central 2%
1 1  dE T 
 Bj  2 
R ct0  dy 
 ~ 10-20 GeV/fm3
II. Hydrodynamics
Huovinen et al
Initial conditions:
ttherm ~ 0.6 -1.0 fm/c
~15-25 GeV/fm3
Heavy ion collisions provide
the laboratory to study high T QCD!
Pt GeV/c
Axel Drees
Fundamental Questions
and our experimental approach at RHIC
Is the quark-gluon plasma the most perfect liquid? If not, what are
its quasi particles?
Hard penetrating probes with highest possible luminosity at top
RHIC energies
Excitation function and flavor dependence of collective behavior
Is there a critical point in the QCD phase diagram and where is it
located?
Low energy scan of hadron production
Low energy scan of dilepton production with highest possible
luminosity
How does the deconfined matter transform into hadrons?
Flavor dependence of spectra and collective flow
How are colliding nuclei converted into thermal quark-gluon
plasma so rapidly?
Hard probes at forward rapidity
Question formulated at QCD workshop, Washington DC 12/2006
Axel Drees
Fundamental Question (I)
Is the quark-gluon plasma the most perfect liquid? If not, what are
its quasi particles?
What are the properties of new state of matter?
Temperature, density, viscosity, speed of sound, diffusion coefficient,
transport coefficients ….
If it’s a fluid: What is the nature a relativistic quantum fluid?
If not: What is it and what are the relevant degrees of freedom?
Key are precision measurements with hard probes
and of collective behavior currently not accessible at RHIC
 RHIC upgrades: improved detectors and increased luminosity
Axel Drees
Key Experimental Probes of Quark Matter
Rutherford experiment
SLAC electron scattering
a  atom
e  proton
discovery of nucleus
discovery of quarks
QGP
penetrating beam
(jets or heavy particles)
absorption or scattering pattern
Nature provides penetrating beams or “hard probes”
and the QGP in A-A collisions
Penetrating beams created by parton scattering before QGP is formed
High transverse momentum particles  jets
Heavy particles  open and hidden charm or bottom
Calibrated probes calculable in pQCD
Probe QGP created in A-A collisions as transient state after ~ 1 fm
Axel Drees
Hard Probes: Light quark/gluon jets
RAA 
Yield AA
N collYield pp
Status
0-12%
STAR
Calibrated probe
Strong medium effect
Jet quenching
Reaction of medium to probe
(Mach cones, recombination, etc. )
Matter is very opaque
Significant surface bias
Limited sensitivity to energy loss
mechanism
trigger 2.5-4 GeV, partner 1.0-2.5 GeV
hydro
reaction of medium vacuum fragmentation
Answers will come from jet tomography (g-jet):
Which observables are sensitive to details of energy
single, two and three particle analysis
loss mechanism?
What is the energy loss mechanism?
Progress limited by:
Do we understand relation between energy loss and
statistics (pT reach)  increase luminosity and/or rate capability
energy density?
kinematic coverage  increase acceptance & add pid
What phenomena relate to reaction of media to probe?
Axel Drees
Jet Tomography at RHIC II
Medium reacting
hadron < 5 GeV
g or 0
trigger
W.Vogelsang NLO
RHIC II L= 20nb-1
LHC: 1 month run
without
RHIC II
<z> ~ 0.1 for particles
in recoil jet
with RHIC II
RHIC II luminosities will give jets up to 50 GeV
 separation of medium reaction and energy loss
 sufficient statistics for 3 particle correlations pT > 5 GeV
 2-3 particle correlations with identified particles
Axel Drees
Hard Probes: Open Heavy Flavor
Electrons from c/b hadron decays
Status
Calibrated probe?
pQCD under predicts cross section by
factor 2-5
Factor 2 experimental differences in pp
must be resolved
Charm follows binary scaling
Strong medium effects
Significant charm suppression
Significant charm v2
Upper bound on viscosity ?
Little room for bottom production
Limited agreement with energy loss
calculations
What is the energy loss mechanism?
Where are the B-mesons?
Answers expected from direct charm/beauty measurements
Progress limited by:
no b-c separation  decay vertex with silicon vertex detectors
statistics (BJ/)  increase luminosity and/or rate capability
Axel Drees
Direct Observation of Charm and Beauty
m
GeV
Detection options with vertex detectors:
• Beauty and low pT charm through displaced e and/or m
• Beauty via displaced J/
• High pT charm through D   K
X
D0 1865
D± 1869
125
317
B0 5279
B± 5279
464
496
e
PHENIX VXT ~2 nb-1
D
Au
D
K
ct
mm
Au
B

J/
X
e
e
RHIC II increases statistics by factor >10
Axel Drees
Hard Probes: Quarkonium
Status
J/ production is suppressed
Similar at RHIC and SPS
Consistent with consecutive melting
of c and ’
Consistent with melting J/ followed
by regeneration
RAA
Recent Lattice QCD developments
Quarkonium states do not melt at TC
J/
Is the J/ screened or not?
Can we really extract screening
length from data?
Answers require “quarkconium” spectroscopy
Progress limited by:
statistics (’, )  increase luminosity and/or rate capability
Axel Drees
Quarkonium and Open Heavy Flavor
Compiled by T.Frawley
Signal
|h| or h
RHIC II 20 nb-1
PHENIX
STAR
<0.35, 1.2-2.4
<1
LHC on month
ALICE
CMS
ATLAS
<0.9, 2.5-4 <2.4
<2.4
J/Y → mm or ee 440,000
220,000
390,000
40,000
8K-100K
Y’→ mm or ee
4000
7,000
700
140-1800
cc → mmg or eeg 120,000 *
-
-
-
-
→ mm or ee
1400
11000**
6000
8000
15,000
B → J/Y → mm
(ee)
8000
2500
12,900
to RHIC
- LHC relative
-
D → K
8000****
8000
30,000***
8,000
-
Luminosity ~ 10%
Running time ~ 25%
Cross
- section ~ 10-50x
~ similar yields!
* large background
** states maybe not resolved
*** min. bias trigger
**** pt > 3 GeV
Will be statistics limited at RHIC II (and LHC!)
Axel Drees
Fundamental Questions (III)
 with TOF barrel
How does the deconfined
matter transform into hadrons?
Status:
Elliptic flow (v2)
v2 of mesons and baryons scale
with constituent quark
number
STAR AuAu 62.4 GeV
Evidence for deconfined
quarks
Hadronisation via recombination
of constituent quarks in QGP
Progress from s and flavor dependence of collective flow
Limited by:
flavor detection capabilities s, c, b mesons and baryons
 vertex detectors and extended particle ID
Axel Drees
Fundamental Questions (IIII)
How are colliding nuclei converted into thermal quark-gluon plasma so rapidly?
Initial state and entropy generation.
What is the low x cold nuclear matter phase?
Status:
Intriguing hints for CGC
(color glass condensate) at RHIC
Bulk particle multiplicities
“mono jets” at forward rapidity
eRHIC
STAR
RHIC
LHC
FAIR
Answers at RHIC from hard probes at forward rapidity,
ultimately EIC needed
Progress at RHIC limited by:
detection capabilities  forward detector upgrades
Axel Drees
Long Term Timeline of Heavy Ion Facilities
2009
2006
2012
2015
RHIC
Vertex tracking, large acceptance, rate capabilities
PHENIX & STAR upgrades
electron cooling “RHIC II”
electron injector/ring “e RHIC”
LHC
FAIR
Phase III: Heavy ion physics
Axel Drees
RHIC Upgrades
On going effort with projects in different stages
Accelerator upgrades
Detector upgrades
forward meson spectrometer
DAQ & TPC electronics
full ToF barrel
heavy flavor tracker
barrel silicon tracker
forward tracker
STAR
PHENIX
EBIS ion source
Electron cooling (x10 luminosity) by 2008
at 200 GeV extra x10
Au+Au ~40 KHz event rate
hadron blind detector
muon Trigger
silicon vertex barrel (VTX)
forward silicon
forward EM calorimeter
Electron cooling at <20 GeV
Additional factor of 10
Au+Au 20 GeV ~15 KHz event rate
Au+Au 2 GeV ~150 Hz event rate
Completed, on going,
proposal submitted, in preparation
Axel Drees
Fundamental Questions
and our experimental approach at RHIC
Is the quark-gluon plasma the most perfect liquid? If not, what are
its quasi particles?
Key measurements and
Hard penetrating
probes with highest
possible luminosity
top
many precision
measurements
unavailable
at RHICattoday!
RHIC energies
Excitation function and flavor dependence of collective behavior
Progress requires:
Is there a critical point in the QCD phase diagram and where is it
located?
Improved
detectors (STAR and PHENIX)
Low energy
scan of hadron
production
vertex
tracking,
large acceptance,
rate capability
Low energy scan of dilepton production with highest possible
luminosity
Luminosity upgrade (RHIC II)
How
does thecooling
deconfined
transform into hadrons?
electron
formatter
all energies
Flavor dependence of spectra and collective flow
How are
colliding nuclei
converted into thermal quark-gluon
Improved
theoretical
guidance
plasma
so rapidly?
phenomenological
tools (e.g. 3-D viscous hydro)
Hard probes
forward
rapidity
lattice
QCDat(e.g.
finite
density)
new approaches (e.g. gauge/gravity correspondence)
Question formulated at QCD workshop, Washington DC 12/2006
Axel Drees
Backup
Axel Drees
Which Measurements are Unique at RHIC?
General comparison to LHC
LHC and RHIC (and FAIR) are complementary
They address different regimes (CGC vs sQGP vs hadronic matter)
Experimental issues: “Signals” at RHIC overwhelmed by “backgrounds” at LHC
Measurement specific (compared to LHC)
Jet tomography:
measurements and capabilities complementary
RHIC: large calorimeter and tracking coverage with PID in few GeV range
Extended pT range at LHC
Charm measurements:
favorable at RHIC
Abundant thermal production of charm at LHC, no longer a penetrating probe
Large contribution from jet fragmentation and bottom decay
Charm is a “light quark” at LHC
Bottom may assume role of charm at LHC
Quarkonium spectroscopy:
J/, ’ , cc easier to interpreter at RHIC
Large background from bottom decays and thermal production at LHC
Rates about equal; LHC 10-50 s, 10% luminosity, 25% running timer
Low mass dileptons:
challenging at LHC
Huge irreducible background from charm production at LHC
Axel Drees
Beyond PHENIX and STAR upgrades?
Do we need (a) new heavy ion experiment(s) at RHIC?
Likely, if it makes sense to continue program beyond 2020
Aged mostly 20 year old detectors
Capabilities and room for upgrades exhausted
Delivered luminosity leaves room for improvement
Nature of new experiments unclear at this point!
Specialized experiments or 4 multipurpose detector ???
Key to future planning:
First results from RHIC upgrades
Detailed jet tomography, jet-jet and g-jet
Heavy flavor (c- and b-production)
Quarkonium measurments (J/, ’ , )
Electromagnetic radiation (e+e- pair continuum)
Status of low energy program
Tests of models that describe RHIC data at LHC
Validity of saturation picture
Does ideal hydrodynamics really work
Scaling of parton energy loss
Color screening and recombination
New insights and short comings of RHIC
detectors will guide planning on time scale 2010-12
Axel Drees
Fundamental Questions (I & II)
Key probe: electromagnetic radiation:
No strong final state interaction
Carry information from time of emission to detectors
e-
e+
g*
g
g and dileptons sensitive to highest temperature of plasma
Dileptons sensitive to medium modifications of mesons
(only known potential handle on chiral symmetry restoration!)
Status
g
First indication of thermal radiation at RHIC
Strong modification of meson properties
Precision data from SPS, emerging data from RHIC
Theoretical link to chiral symmetry restoration
remains unclear
NA60
Can we measure the initial temperature?
Is there a quantitative link from dileptons to
chiral symmetry resoration?
Answers will come with more precision
data  upgrades and low energy running
Axel Drees
EBIS ion source
~30% higher  with U+U
Luminosity increase at 200 GeV
x4 above design achieved by 2008
Electron cooling at 200 GeV extra x10
Au+Au ~40 KHz event rate
Electron cooling at <20GeV
Additional factor of 10
Au+Au 20 GeV ~15 KHz event rate
Au+Au 2 GeV ~150 Hz event rate
Expected whole vertex minbias event rate [Hz]
RHIC II
Accelerator upgrades
Increase by additional
factor 10
with electron cooling
T. Roser, T. Satogata
Axel Drees
Quarkonium and Open Heavy Flavor
Compiled by T.Frawley
Signal
|h| or h
PHENIX
ALICE
CMS
ATLAS
<0.35, 1.2-2.4
STAR
<1
<0.9, 2.5-4
<2.4
<2.4
J/Y → mm or ee
440,000
220,000
390,000
40,000
8K-100K
Y’→ mm or ee
8000
4000
7,000
700
140-1800
cc → mmg or eeg
120,000 *
-
-
-
-
→ mm or ee
1400
11000**
6000
8000
15,000
B → J/Y → mm (ee)
8000
2500
12,900
-
-
D → K
8000****
30,000***
8,000
-
-
Potential improvements with dedicated experiment
4 acceptance
background rejection
J/Y, Y’

cc
LHC relative to RHIC
10x
2-10x
????
Note: for B, D increase by factor 10 extends pT by ~3-4 GeV
Luminosity ~ 10%
Running time ~ 25%
Cross section ~ 10-50x
~ similar yields!
Will be statistics limited at RHIC II (and LHC!)
* large background
** states maybe not resolved
*** min. bias trigger
Axel Drees
**** pt > 3 GeV
2
Future PHENIX Acceptance for Hard Probes
NCC
NCC
MPC
MPC
EMCAL
f coverage
EMCAL
HBD
0
VTX & FVTX
-3
-2
-1
0
1
2
3 rapidity
(i) 0 and direct g with combination of all electromagnetic calorimeters
(ii) heavy flavor with precision vertex tracking with silicon detectors
combine (i)&(ii) for jet tomography with g-jet
(iii) low mass dilepton measurments with HBD + PHENIX central arms
Axel Drees
RHIC Upgrades Overview
Upgrades
High T QCD
e+e-
heavy
jet
flavor
tomography
X
O
Spin
quarkonia
W
Low
x
DG/G
PHENIX
hadron blind detector (HBD)
X
Vertex tracker (VTX and FVTX)
X
m trigger
forward calorimeter (NCC)
O
O
O
X
O
X
O
O
X
STAR
time of flight (TOF)
O
X
O
Heavy flavor tracker (HFT)
X
O
O
tracking upgrade
O
O
X
Forward calorimeter (FMS)
DAQ
RHIC luminosity
O
O
O
X
O
X
X
O
O
O
O
X
X
O
O
O
X upgrade critical for success
O upgrade significantly enhancements program
Axel Drees
Comparison of Heavy Ion Facilities
Initial conditions
FAIR: cold but dense baryon
rich matter
fixed target p to U
sNN ~ 1-8 GeV U+U
Intensity ~ 2 109/s  ~10 MHz
~ 20 weeks/year
RHIC: dense quark matter to
hot quark matter
FAIR  TC
Collider p+p, d+A and A+A
sNN ~ 5 – 200 GeV U+U
Luminosity ~ 8 1027 /cm2s  ~50 kHz
~ 15 weeks/year
LHC 3-4 TC
RHIC  2 TC
LHC: hot quark matter
RHIC is unique and at “sweet spot”
Complementary programs with large overlap:
High T: LHC
 adds new high energy probes
 test prediction based on RHIC data
High r: FAIR
 adds probes with ultra low cross section
Collider p+p and A+A
Energy ~ 5500 GeV Pb+Pb
Luminosity ~ 1027 /cm2s  ~5 kHz
~ 4 week/year
Axel Drees
Midterm Strategy for RHIC Facility
Key measurements require upgrades of detectors and/or RHIC luminosity
Detectors:
Particle identification 
reaction of medium to eloss,
recombination
Displaced vertex detection 
open charm and bottom
Increased rate and acceptance
 Jet tomography,
quarkonium, heavy flavors
Dalitz rejection  e+e- pair
continuum
Forward detectors  low x,
CGC
Accelerator:
EBIS  Systems up to U+U
Electron cooling  increased
luminosity
Axel Drees
PHENIX Detector Upgrades at a Glance
Central arms:
Electron and Photon measurements
Electromagnetic calorimeter
Precision momentum determination
Dalitz/conversion rejection (HBD)
Precision vertex tracking (VTX)
Hadron identification
PID (k,,p) to 10 GeV (Aerogel/TOF)
Muon arms:
Muon
Identification
Momentum determination
High rate trigger (m trigger)
Precision vertex tracking (FVTX)
Electron and photon measurements
Muon arm acceptance (NCC)
Very forward (MPC)
Axel Drees
STAR Upgrades
Full Barrel
Time-ofFlight system
DAQ and
TPC-FEE
upgrade
Forward
Meson
Spectrometer
Forward tripleGEM EEMC
tracker
Integrated
Tracking
Upgrade
HFT pixel
detector
Barrel silicon
tracker
Forward
silicon
tracker
Axel Drees
Comments on High pT Capabilities
Region of interest for associated particles
up to pT ~ 5 GeV
LHC
Orders of magnitude larger cross sections
~3 times larger pT range
RHIC with current detectors (+ upgrades)
Sufficient pT reach
Sufficient PID for associated particles
What is needed is integrated luminosity!
Axel Drees