John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04 The Quenching of Jets at...
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Transcript of John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04 The Quenching of Jets at...
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
The Quenching of Jets at RHIC – Evidence for Hot Bulk QCD Matter
• Introduction• Relativistic Heavy Ion Collider (RHIC)• Creating Hot Bulk QCD Matter – Overview• Using Hard Scattering to Probe the Medium
• Suppression of High Pt Particles• Jet Quenching (Parton Energy Loss) Properties of the Medium
• Conclusions & Expectations
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Early Universe
National Geographic(1994)
&Michael Turner
quark-hadronphase transition2 x 1012 Kelvin
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Lattice QCD at Finite Temperature
F. Karsch, et al.Nucl. Phys. B605 (2001) 579
Action density in 3 quark system in full QCDH. Ichie et al., hep-lat/0212036
G. Schierholz et al., Confinement 2003
TC ~ 175 8 MeV C ~ 0.3 - 1 GeV/fm3
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Phase Diagram of QCD Mattersee: Alford, Rajagopal, Reddy, Wilczek Phys. Rev. D64 (2001) 074017
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hot Bulk QCD Matter (QGP)• Standard Model Lattice Gauge Calculations predict
Deconfinement phase transition at high T in QCD
• Cosmology Quark-hadron phase transition in early Universe
• Astrophysics Cores of dense stars
• Establish bulk properties of QCD at high T and density
• Can we make it in the lab?
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Relativistic Heavy Ion Collider
STAR
PHENIX
PHOBOS BRAHMS
RHIC
Design Performance Au + Au p + p
Max snn 200 GeV 500 GeV
L [cm-2 s -1 ] 2 x 1026 1.4 x 1031
Interaction rates 1.4 x 103 s -1 3 x 105 s -1
Two Concentric Superconducting Rings
Ions: A = 1 ~ 200, pp, pA, AA, AB
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Relativistic Heavy Ion Collider and Experiments
STARSTAR
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Space-time Evolution of RHIC Collisions
e
space
time jet
Hard Scattering + Thermalization (< 1 fm/c)
AuAu
Exp
ansi
on
Hadronization
p K
Freeze-out(~ 10 fm/c)
QGP (~ few fm/c)
e
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
What Can We Learn from Collisions at RHIC?• Early Stage of Collisions
– Parton (fast quark and gluon) scattering and propagation– Pressure buildup from azimuthal asymmetries (elliptic flow)
• Thermodynamic Properties– Bjorken longitudinal expansion and energy density– Baryo-chemical potential from baryon density/particle ratios– Pressure from flow– Entropy from particle production– Temperature from chemical freezeout (particle ratios)– Temperature from thermal freezeout (particle spectra)
• Phase Transitions?– Deconfinement (s,cc, ,bb?)– Chiral Restoration
• General - Collision Geometry, Space-time Evolution, Freezeout– number of participants vs centrality– stages of collisions (space-time diagram as function of geometry)– short-lived resonances– hadronization timescales
• Medium Effects?– on masses and widths of resonances– on parton propagation, other?
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Creating & Probing Hot Nuclear Matter at RHIC
• Create Hot Nuclear Matter– Equilibration? Thermodynamic properties?– Equation of State?– How to determine its properties?
• Probe
Soft Physics reflect bulk properties(pT < 2 GeV/c)
Hard Scattering & Heavy Quarks probe the medium
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Characteristics of Collisions at RHIC from Experiments
global observations:
Large produced particle multiplicities dnch/d |=0 = 670, Ntotal ~ 7500
15,000 quarks in final state, > 92% are produced quarksLarge energy densities dn/ddET/d GeV/fm3
x nuclear densityLarge elliptic flow Extreme early pressure gradients and gluon densities
quark-gluon equation of state!
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Early Pressure in System Elliptic Flow?
x
z
y
Initial Ellipticity(coord. space)
ReactionPlane (xz)
Sufficient interactions early (~ 1 fm/c) in system to respond to early pressure? before self-quench (insufficient interactions)?
System able to convert original spatial anisotropy into momentum anisotropy?
Sensitive to early dynamics of initial system
p
p
Azimuthal anisotropy(momentum space)
?
)
FlowElliptic
2cos2
FlowDirected
cos2 Isotropic
1 ( 2
121
2
3
3
RPRPtt
vvdydpp
d
pd
dE
x
y
p
patan
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Large Elliptic Flow Observed
• Azimuthal asymmetry of charged particles: dn/d ~ 1 + 2 v2(pT) cos (2) + ...
x
z
y
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Characteristics of Collisions at RHIC from Experiments
global observations:
Large produced particle multiplicities dnch/d |=0 = 670, Ntotal ~ 7500
92% of (>15,000) quarks of final state are produced quarksLarge energy densities dn/ddET/d GeV/fm3 –
x nuclear densityLarge elliptic flow Large early pressure gradients and gluon densities
quark-gluon equation of state!
“chemical” equilibration (particle yields & ratios):
Do particles yields represent equilibrium values?
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
• Chemically and thermally equilibrated fireball at one temperature T and one ( baryon) chemical potential : – One ratio (e.g., p / p ) determines / T :– Second ratio (e.g., K / ) provides T
• Then all hadronic yields and ratios determined:
Particle Ratios Chemical Equilibrium Temperature
pdedn E 3/)(~ Tμ
TμTμ
Tμ/2
/)(
/)(
ee
e
p
pE
E
Ratios equilibrium values
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
QCD Phase Diagram
At RHIC:
T = 177 MeV
T ~ Tcritical (QCD)
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hard Scattering to Probe the Hot Bulk QCD Medium
hadrons
leading particle
hadrons
leading particle
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
• New for heavy ion physics Hard Parton Scattering sNN = 200 GeV at RHIC (vs 17 GeV at SPS)
Using Hard Scattered Partons to Probe the Medium
• Jets and mini-jets
30 - 50 % of particle production
high pt leading particles (jets?)
azimuthal correlations
vacuum
medium
• Scattered partons propagate through matter
radiate energy (~ few GeV/fm) in colored medium
• suppression of high pt particles
called “parton energy loss” or “jet quenching”• alter di-jets and azimuthal correlations
hadrons
leading particle
hadrons
leading particle
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Inclusive Hadron pt-spectra: s = 200 GeV AuAu
power law:
pp = d2N/dpt2 = A (p0+pt)-n
Preliminary
STAR
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hadron Spectra: Comparison of AA to NN
Nuclear Modification Factor RAA:AA = Nucleus-NucleusNN = Nucleon-Nucleon
ddpdT
ddpNdpR
TNN
AA
TAA
TAA /
/)(
2
2
Nuclear overlap integral:# binary NN collisions / inelastic NN cross section
NN cross section
AA cross section
AA
(pQCD)
Parton energy loss R < 1 at large Pt
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Brookhaven Science AssociatesU.S. Department of Energy
Suppression of High Transverse Momentum Hadrons at RHIC
• Large transverse momentum hadrons are suppressed in central collisions at RHIC
√snn = 17.3 GeV
√snn = 31 GeV
√snn = 130 GeV
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Centrality Dependence of Suppression at RHIC
Au+Au130 GeV
Phys. Rev. Lett. 89, 202301 (2002)STAR
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Brookhaven Science AssociatesU.S. Department of Energy
Factor 4 - 5 Suppression of High Transverse Momentum Hadrons at Top RHIC Energy
• Large transverse momentum hadrons are suppressed by factor ~ 4-5 in central collisions at RHIC
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Is Origin of Suppression Initial or Final State?
Final state
parton energy loss?
A + A collisions in medium:
gluon saturation?
nuclear effects in initial state
Initial state
no partonenergy loss
nuclear effects in initial state
gluon saturation?p,d + A collisions -
no medium
Distinguish effects -initial statefinal state
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Unique to Heavy Ion Collisions!• Crucial control measurement using d-Au collisions
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Extreme Energy Densities! – Au-Au suppression
(I. Vitev and M. Gyulassy, hep-ph/0208108)– d-Au enhancement (I. Vitev, nucl-th/0302002 )
understood in an approach that combines multiple scattering with absorption in a dense partonic medium
high pT probesrequire
dNg/dy ~ 1100
> 100 0Au-Au
d-Au
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hard Scattering (Jets) as a Probe of Dense Matter II
Jet event in eecollision STAR p + p jet event
Can we see jets in high energy Au+Au?
STAR Au+Au (jet?) event
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
In QCD Medium
Additional kT
Significant energy loss? high pT suppression
Sensitive to color Sensitive to color properties of mediumproperties of medium
coneR
Studying Jets and High Pt Particles in Detail at RHIC
Hard probes early times
Calculable: pQCD
Abundant at RHIC, LHC
kT“radiative corrections”
pre- and post-scattering
di-jet:
Fragmentation:
z hadron
parton
p
p
Fragmentation:
p(hadron)p (parton)
z =Induced Gluon Radiation
~collinear gluons in cone “Softened” fragmentation
in je
i j t
t
n e
: increases
z : decreases
chn
Gyulassy et al., nucl-th/0302077
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Use Geometry to Vary Parameters of Collision
x
z
y
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Using p+p to Study Au+Au Jet Correlations
Assume:high pT triggered Au+Au event
is a superposition:high pT triggered p+p event +
elliptic flow of AuAu event
C2(Au Au)C2(p p) A *(1 2v22 cos(2))
– v2 from reaction plane analysis
– A from fit in non-jet region (0.75 < || < 2.24)
Peripheral Au + Au
Away-side jet
Central Au + Au
disappears
STAR 200 GeV/cperipheral & central Au+Au
p+p minimum bias4<pT(trig)<6 GeV/c
2<pT(assoc.)<pT(trig)
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Path Length Dependence of Di-jet Topologies
y
x
pTtrigger=4-6 GeV/c, 2<pT
associated<pTtrigger, ||<1
in-plane
Out-of-plane
Back-to-back suppression out-of-plane stronger than in-plane
Effect of path length on suppression is experimentally accessible
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hammering the Nail in the Coffin
C2(Au Au)C2(p p) A * (1 2v22 cos(2))
• STAR azimuthal correlation function shows ~ complete absence of “away-side” jet
Surface emission only?• “Partner” in hard scatter is
absorbed in the dense medium
Pedestal&flow subtracted
no jet quenching!
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hard Scattering Conclusion I
• The hard scattering data at RHIC from p-p, Au-Au and d-Au collisions establish existence of a new final-state effect - early (parton!) energy loss – from dense matter (new state of matter?) in central Au-Au collisions
Au + Au Experiment d + Au Control Experiment
Preliminary DataFinal Data
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Hard Scattering Conclusion II
High Pt hadrons suppressed in central Au + Au enhanced in d + AuBack-to-back Jets Di-jets in p + p, d + Au
(all centralities) Away-side jets quenched
in central Au + Au emission from surface
x
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Suggest QGP-based picture of RHIC collision evolution
Major Findings of RHIC to DateMajor Findings of RHIC to Date
Quark coalesce./flow constituent q d.o.f.
Ideal hydro - Early thermalization + quark-gluon EOS
pQCD parton E loss -large early gluon density-Opaque!
Statistical model
Rapid u, d, s equilibration near Tcrit
Gluon saturation or Color Glass Condensate? large initial gluon density
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
To do!
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
Deconfined QGP?
cc, bb suppression / melting sequence
Strangeness enhancement?
Thermalized?
Open charm, beauty, multiply-strange baryon production & flow
Establish properties of the QCD medium
Probe parton E-loss with higher pT triggers, jets, -jet
Flavor dependence of suppression & propagation
Light vector mesons (mass and width modifications)
Direct Photon Radiation?
New phenomena…….
RHIC II!
“the adventure continues!”
John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04
Still the beginning
A Comprehensive New Detector for RHIC II Physics
Exploratory Working Group on a Comprehensive New Detector for RHIC-II Physics
L. Bland, P. Steinberg, T. Ullrich (BNL), M. Calderon (BNL/Indiana),S. Margetis (Kent State),B. Surrow (MIT),J. Rak (New Mexico),M. Lisa, D. Magestro (Ohio State),R. Lacey (Stony Brook),G. Paic (UNAM Mexico),T. Nayak (VECC Calcutta),R. Bellwied, C. Pruneau, A. Rose, S. Voloshin (Wayne State),H. Caines, A. Chikanian, E. Finch, J.W. Harris, C. Markert, J. Sandweiss, N. Smirnov (Yale)
NSAC Review, BNL, June 3, 2004
The Physics Pillars of a New RHIC-II Detector
What are the detailed properties of the sQGP and can we probe a weakly interacting plasma state ?
How do particles acquire mass and is chiral symmetry
restored in the dense medium ?
Is there another phase (CGC) of matter at low x, what are its features (how does it melt into the QGP) ?
What is the structure and dynamics inside the proton (parton spin, L) and is parity violation important ?
HCAL & muon detector. 15 planes,(5 cm Fe, streamer tubes, 0.3 x 4 cm resolution) (available)
EMC; Crystals + Fe(Pb)/Sc (accordion type)
or LAr variant, 6x6 mrad towers (available)
Tracking:• Si Vertex Detector (Si Pixel)• Primary Tracker: multi-layer Si strip or miniTPC• Pattern Pad Detectors in Barrel and End Caps
“Very ForwardDirection”(see next slide)
R = 2.8 m
dZ = 3.0 m
PID Detectors:Cherenkov threshold (aerogel), RICH, Photon Converters, ToF (STAR clone?)
Detector Concept: central || < 3SC Magnet Coil, 1.5 T (“available”) pT > 0.5 GeV/c
Summary
The New Comprehensive Detector Presents
Unique New Physics Programs at RHIC II: - jet/leading particle physics program
flavor dependent modification of fragmentation due to medium Quarkonium physics program
deconfinement, initial conditions, nuclear effects
Unique Physics Contributions to: Gluon saturation (CGC) Chiral symmetry restoration Structure and dynamics of the proton
New (as yet) undetermined physics