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Playing%20with%20Goo%20-%20Attempting%20to%20Recreate%20Primordial%20Matter%20at%20a%20Trillion%20K

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Title: Playing%20with%20Goo%20-%20Attempting%20to%20Recreate%20Primordial%20Matter%20at%20a%20Trillion%20K


1
Playing with Goo - Attempting to Recreate
Primordial Matter at a Trillion K
The test of all knowledge is experiment
(R.P. Feynman, Feynman Lectures on Physics, Book
1, Chapter 1, Page 1)
2
Evolution of the universe
10-44 sec Quantum Gravity Unification of all 4 forces 1032 K
10-35 sec Grand Unification E-M/Weak Strong forces 1027 K
10-35 sec ? Inflation universe exponentially expands by 1026 1027 K
2 10-10 sec Electroweak unification E-M weak force 1015 K
210-6 sec Proton-Antiproton pairs creation of nucleons 1013 K
6 sec Electron-Positron pairs creation of electrons 6 x 109 K
3 min Nucleosynthesis light elements formed 109 K
106 yrs Microwave Background recombination - transparent to photons 3000 K
109 yrs ? Galaxy formation bulges and halos of normal galaxies form 20 K
Reheating Matter ?
The universe gets cooler !
? Need temperatures around 1.51012 K (200 MeV)
Stars convert gravitational energy to
temperature. They replay and finish
nucleosynthesis at 15106 K in the center of
our sun.

3
How and why do we do this research?
To explore the phase diagram of nuclear matter
  • How
  • By colliding nuclei in lab.
  • By varying energy (vs) and size (A).
  • By studying spectra and
  • particle correlations.

Rajagopal and Wilczek, hep-ph/-0011333
To probe properties of dense nuclear matter
  • How
  • By colliding most massive and
  • highest energy nuclei.
  • By comparing to more elementary
  • systems.
  • Through high p? studies.

4
The early predictions
- New Scientist
most dangerous event in human history - ABC News
Sept 99
"Big Bang machine could destroy Earth" -The
Sunday Times July 99
No the experiment will not tear our region of
space to subatomic shreds. - Washington Post
Sept 99
the risk of such a catastrophe is essentially
zero. B.N.L. Oct 99
Apocalypse2 ABC News Sept 99
Will Brookhaven Destroy the Universe? NY Times
Aug 99
5
Lattice QCD calculations
  • Coincident transitions deconfinement and chiral
    symmetry restoration
  • Recently extended to mBgt 0, order still unclear
    (1st, 2nd, crossover ?)

TC 170 MeV
F. Karsch, hep-ph/0103314
6
RHIC _at_ Brookhaven National Lab.
Relativistic Heavy Ion Collider
h
Long Island
  • 2 concentric rings of 1740 superconducting
    magnets
  • 3.8 km circumference
  • counter-rotating beams of ions from p to Au
  • Previous Runs
  • AuAu _at_ ?sNN130 GeV 200 GeV
  • pp _at_ ?sNN 200 GeV
  • dAu _at_ ?sNN 200 GeV
  • Present Run
  • Au-Au ?sNN200 GeV

7
What Does a RHIC Collision Look Like?
A Central AuAu Collision Npart ? ?sNN
40 TeV 6 mJoule Our Ears are
sensitive to 10-11 ergs 10-18 Joule
10-12 mJoule If a RHIC
Collision was converted solely into noise thats
one
HI Collisions converted into COPIOUS particle
production
BIG BANG!
8
Peripheral Collision
Color ? Energy loss in TPC gas
9
Central Collision
10
The Experimental Setup
11
How a TPC works
  • Tracking volume is an empty volume of gas
    surrounded by a field cage
  • Drift gas Ar-CH4 (90-10)
  • Pad electronics 140000 amplifier channels with
    512 time samples

Provides 70 M pixel, 3D image
12
Needle in the Hay-Stack!
How do you do tracking in this regime? Solution
Build a detector so
you can zoom in close and see individual tracks
high resolution
Clearly identify individual tracks
Good tracking efficiency
Pt (GeV/c)
13
A theoretical view of the collision
2
  • Hadronic ratios.
  • Resonance production.
  • p? spectra.
  • Partonic collectivity.
  • High p? measurements.

Tc Critical temperature for transition to
QGP Tch Chemical freeze-out (Tch ? Tc)
inelastic scattering stops Tfo Kinetic
freeze-out (Tfo ? Tch) elastic scattering
stops
14
Geometry of heavy-ion collisions
Particle production scales with increasing
centrality
spectators
peripheral (grazing shot)
central (head-on) collision
Number participants (Npart) number of nucleons
in overlap region
Number binary collisions (Nbin) number of
equivalent inelastic nucleon-nucleon
collisions
Nbin Npart
15
Exceed critical energy density
Electromagnetic Calorimeter measures transverse
energy in collisions
Bjorken-Formula for Energy Density
Time it takes to thermalize system (t0 1 fm/c)
6.5 fm
pR2
5 times above ecritical (0.5-0.7 GeV/fm3) from
lattice QCD Have the Energy Density!!
3 GeV/fm3 30 times normal nuclear density1.5
to 2 times higher than at
CERN/SPS (?s 17 GeV)
16
Particle creation and distributions
19.6 GeV
130 GeV
200 GeV
PHOBOS Preliminary
dNch/dh
Central
Peripheral
h
  • Central 130 GeV AuAu 4200 charged particles
  • Central 200 GeV AuAu 4800 charged particles
    (20 in pp)
  • Plateau at y 0 ? boost invariant

Total multiplicity per participant pair scales
with Npart
Not just a superposition of p-p
To get much further need PID
17
STAR Data to Date
  • So far we measured only
  • p0, p?, K?
  • K0(892), K0s, r0, ?, f0
  • p, d,?He3, D
  • L, L(1520), ??, ?, ?, ??, ?0
  • D0, D, D?, e?
  • and all antiparticles, and correlations, and

How to characterize this embarrassment of riches?
18
A theoretical view of the collision
Chemical freeze out (Tch ? Tc) inelastic
scattering stops
19
Net-baryon number at mid-rapidity
  • ?B - all from pair production
  • B - pair production
  • transported from ybeam
  • to y0
  • ?B/B ratio 1
  • - Transparent collision
  • ?B/B ratio 0
  • - Full stopping, little pair production

STAR Preliminary
  • 2/3 of proton from pair production
  • First time pair production dominates
  • Still some baryons from beam

Same trend and values for d-Au, p-p and Au-Au
20
Strangeness enhancement
General arguments for enhancement 1. Lower
energy threshold TQGP gt TC ms 150
MeV Note that strangeness is conserved in
the strong interaction 2. Larger production
cross-section 3. Pauli blocking (finite chemical
potential)
Strange particles with charged decay modes
Enhancement is expected to be more pronounced for
multi-strange baryons and their anti-particles
Arguments still valid but now use Strange
particles for MUCH MORE
21
Strangeness enhancement?
  • Canonical (small system)
  • Computed taking into account energy to create
    companion to ensure conservation of strangeness.
    Quantum Numbers conserved exactly.
  • Grand Canonical limit (large system)
  • Just account for creation of particle itself.
    The rest of the system acts as a reservoir and
    picks up the slack. Quantum Numbers conserved
    on average via chemical potential.
  • Phase space suppression of strangeness in
  • small system/low temperature.
  • Have to take care about the denominator
  • canonical suppression
  • increases with strangeness
  • decreases with volume
  • observed enhancements
  • Hamieh et al. Phys. Lett. B486 (2000) 61

22
Correlation volume
  • Grand Canonical description is only valid in a
    system in equilibrium that is large.
  • BUT being large is not a sufficient condition for
    being GC!
  • if AA were just superposition of pp STILL need
    to treat CANONICALLY
  • System must know it is large...
  • Must know that an O generated here can be
    compensated by, say, an O- on the other side of
    the fireball!
  • what counts is the correlation volume
  • How does the system KNOW its big?
  • Not from hadronic transport no time
  • One natural explanation returning from
    deconfined state (QGP)

23
Phase space suppression less at RHIC
  • See drop in enhancement at higher energy
  • Enhancement values as predicted by model
  • Correlation volume not well modeled by Npart

System is in G.C. state for most central data
24
Models to evaluate Tch and ?B
  • Statistical Thermal Model
  • F. Becattini P. Braun-Munzinger, J. Stachel, D.
    Magestro
  • J.Rafelski PLB(1991)333 J.Sollfrank et al.
    PRC59(1999)1637
  • Assume
  • Ideal hadron resonance gas
  • thermally and chemically equilibrated fireball
    at hadro-chemical freeze-out
  • Recipe
  • GRAND CANONICAL ensemble to describe partition
    function ? density of particles of species ?i
  • fixed by constraints Volume V, , strangeness
    chemical potential ?S, isospin
  • input measured particle ratios
  • output temperature T and baryo-chemical
    potential ?B

Particle density of each particle
Qi 1 for u and d, -1 for ?u and ?d si 1 for
s, -1 for ?s gi spin-isospin freedom mi
particle mass Tch Chemical freeze-out
temperature mq light-quark chemical
potential ms strangeness chemical
potential gs strangeness saturation factor
Compare particle ratios to experimental data
25
Thermal model fit to data
  • Particle ratios well described
  • Tch 160 ? 5 MeV
  • mB 24 ? 5 MeV
  • ms 1.4 ?1.4 MeV
  • gs 0.99 ?0.07

Created a Large System in Local Chemical
Equilibrium
26
Phase Diagram from AGS to RHIC
Tch MeV mB MeV
AGS ?s 2-4 GeV 125 540
SPS ?s 17 GeV 165 250
RHIC ?s 130-200 GeV 175 30
Again slight variations in the models
QCD on Lattice Tc 1738 MeV, Nf2 Tc 1548
MeV, Nf3
Remember Measure hadrons not partons so cant
measure Tgt Tc with this method
27
Tch systematics
  • Hagedorn (1965)
  • If the resonance mass spectrum grows
    exponentially
  • (and this seems to be the case)
  • There is a maximum possible temperature for a
    system of hadrons.

Blue Exp. fit Tc 158 MeV
r(m) (GeV-1)
filled AA open elementary
Green - 1411 states of 1967 Red 4627 states of
1996
m
Satz Nucl.Phys. A715 (2003) 3c
Seems he was correct dont get above Tch 170
MeV
28
A theoretical view of the collision
2
Chemical freeze out (Tch ) 170 MeV Time between
Tch and Tfo
29
Thermal model reproduces data
Do resonances destroy the hypothesis?
Created a Large System in Local Chemical
Equilibrium
30
Resonances and survival probability
  • Initial yield established at chemical
  • freeze-out
  • Decays in fireball mean daughter
  • tracks can rescatter destroying part of
  • signal
  • Rescattering also causes regeneration
  • which partially compensates
  • Two effects compete Dominance
  • depends on decay products and
  • lifetime

?
lost
K
K
measured
Chemical freeze-out
Kinetic freeze-out
time
Ratio to stable particle reveals information on
behaviour and timescale between chemical and
kinetic freeze-out
31
Resonance ratios
Life time fm/c ? 40 L 13 K
4
Thermal model 1 Tch 177 MeV mB 29 MeV
NOT ENOUGH
UrQMD 2
Nch
1 P. Braun-Munzinger et.al., PLB 518(2001) 41
D.Magestro, private communication 2 Marcus
Bleicher and Jörg Aichelin Phys. Lett.
B530 (2002) 81-87. M. Bleicher, private
communication
Need gt4fm between Tch and Tfo
Small centrality dependence little difference
in lifetime!
32
A theoretical view of the collision
2
Chemical freeze out (Tch ) 170 MeV Time between
Tch and Tfo ? 4fm Kinetic freeze-out (Tfo ? Tch)
elastic scattering stops
33
Kinetic freeze-out and radial flow
Want to look at how energy distributed in
system. Look in transverse direction so not
confused by longitudinal expansion
Slope 1/T
Look at p? or m? ?(p?2 m2 ) distribution
A thermal distribution gives a linear
distribution dN/dm? ? e-(m?/T)
If there is radial flow
dN/dm?- Shape depends on mass and size of flow
Heavier particles show curvature
34
Radial flow and hydro dynamical model
Shape of the m? spectrum depends on particle
mass Two Parameters Tfo and b
p,K,p fit
E.Schnedermann et al, PRC48 (1993) 2462
?r ?s (r/R)n
Tfo 90 ? 10 MeV, lt ?? gt 0.59 0.05c
35
Flow of multi-strange baryons
  • ?, K, p Common thermal freeze-out at Tfo 90
    MeV
  • lt??gt 0.60 c
  • ? Shows different thermal freeze-out behavior
  • Tfo 160 MeV
  • lt??gt 0.45 c

Higher temperature Lower transverse flow Probe
earlier stage of collision?
But Already some radial flow!
Tfo Tch Instantaneous Freeze-out of
multi-strange particles? Early Collective Motion?
36
A theoretical view of the collision
2
Chemical freeze out (Tch ) 170 MeV Time between
Tch and Tfo ? 4fm Kinetic freeze-out (Tfo) 90
MeV (light particles) Very Early Times
37
Early collective motion?
Look at Elliptic Flow
Equal Energy Density lines
P. Kolb, J. Sollfrank, U. Heinz
AGS
Almond shape overlap region in coordinate space
Anisotropy in momentum space
Interactions
v2 2nd harmonic Fourier coefficient in dN/d?
with respect to the reaction plane
38
Measuring elliptic flow
Measuring elliptic flow
K.M. OHara et al, Science 298, 2179, 2002
K.M. OHara et al, Science 298, 2179, 2002
  • Example from ultra cold trapped Li6 atoms
    measurement
  • Normal gas is transparent l gtgt L and expands
    without
  • collisions isotropically
  • Magnetic field used to induce strong resonant
    interactions
  • - effectively zero mean free path l ltlt L

Cant see the plasma so probe number of particles
as function of angle with respect to reaction
plane.
?lab-?plane
Reaction Plane
  • Release the trap and let it expand
  • In strong coupling regime l ltlt L it explodes
    hydrodynamically!

Fourier analysis ? 12v2cos(2(?lab-?plane)) as fn
p?
39
v2 at hydrodynamical levels
  • Multi-strange particles show sizeable elliptic
    flow!
  • Reach hydro. limit

Hydro P. Huovinen et al.
Hydrodynamical models describe data well for pT
(lt 2.5 GeV/c) v2(p) gt v2(K) gt v2 (p)
gt v2(L) ? compatible with early equilibration
  • All particles v2 seem to saturate at high p?

40
Why high p? physics at RHIC?
Early production in parton-parton scatterings
with large Q2. Direct probes of partonic phases
of the reaction
  • New penetrating probe at RHIC
  • Attenuation or absorption of jets jet
    quenching.
  • Suppression of high p? hadrons.
  • Modification of angular correlation.
  • Changes of particle composition PID needed

41
Au-Au and p-p inclusive charged hadrons
nucl-ex/0305015
42
The control experiment d-Au
  • Partonic energy loss/final state vs gluon
    saturation/intial state

Medium?
Nucleus-nucleus collision
  • Collisions of small with large nuclei quantify
    all cold nuclear effects.
  • Small Large distinguishes all initial and final
    state effects.

43
Jets in Heavy Ion Collisions?
ee- ? q q (OPAL_at_LEP)
p-p ?jetjet (STAR_at_RHIC)
Au-Au ???? (STAR_at_RHIC)
Jets in Au-Au hopeless Task?
No, but a bit tricky
44
Jets and two-particle azimuthal distributions
pp ? dijet
  • Df ? 0 peripheral and central Au-Au similar to
    p-p
  • Df ? p strong suppression in central Au-Au
  • Trigger highest p? track, p? gt4 GeV/c
  • ?? distribution between trigger and all
    particles with 2 GeV/c lt p? lt p? trigger
  • normalize to number of triggers
  • d-Au backwards correlation is visible

Jet suppression is a final state effect.
45
Path length related to energy loss
  • Energy loss related to position where partons
    collide
  • Partons leaving in-plane short path length ?
    small energy loss
  • Partons leaving out-of -plane larger path
    length ?more energy loss

46
Initial Anisotropy and energy loss
  • Au-Au Away-side suppression larger in the
    out-of-plane direction
  • Hypothesis seems verified

47
Nuclear modification factor
Hard Physics -
Scales with Nbin Number of binary collisions
number of equivalent inelastic nucleon-nucleon
collisions
Nuclear Modification Factor
Can replace p-p with peripheral Rcp
48
Suppression of inclusive hadrons at high p?
STAR, nucl-ex/0305015
pQCD Shadowing Cronin
energy loss
pQCD Shadowing Cronin Energy Loss
  • central AuAu collisions factor 4-5
    suppression.
  • p? gt5 GeV/c suppression independent of p?.
  • pQCD describes data only when energy loss
    included.

49
d-Au control experiment
Enhancement is the well known Cronin Effect
Charged Particle
Au-Au, RAA ltlt 1 dAu, RdAu gt 1
RAA results confirm there are final state effects
50
Partonic Energy Loss in Dense Matter
Bjorken, Baier, Dokshitzer, Mueller, Pegne,
Schiff, Gyulassy, Levai, Vitev, Zhakarov, Wang,
Wang, Salgado, Wiedemann,
Multiple soft interactions
Gluon Bremsstrahlung
Opacity Expansion
  • Deduced initial gluon density at t0 0.2 fm/c
  • dNglue/dy 800-1200, e 15
    GeV/fm3
  • Recall QCD on Lattice (2-flavor)
  • TC 173?8 MeV, eC (6?2) T 4, eC 0.70 ?
    0.27 GeV/fm3
  • Recall Cold nuclear matter
  • ecold u / 4/3pr03
    ecold 0.13 GeV/fm3

Strong dependence on ?glue measure DE ? color
charge density at early hot, dense phase
51
Suppression of identified particles
Two groups (2 lt p?lt 6GeV/c) - K0s, K?, K ?
mesons - L, X ? baryons
Mass or meson/baryon effect?
L
L show different behaviour to K Suppression
of K sets in at lower p?
Rcp
K
Come together again at p? 6 GeV? standard
fragmentation?
Clearly not mass dependence Higher stats. this
run get W and f
52
Parton coalescence and medium p?
  • Mesons
  • When slope exponential
  • coalescence wins
  • When slope power law
  • fragmentation wins

recombining partons p1p2ph
fragmenting parton ph z p, zlt1
  • Baryons
  • Recombination
  • p?(baryons) gt p?(mesons) gt p?(quarks)
  • (coalescence from thermal quark

  • distribution ...)
  • Pushes soft physics for baryons out to
  • 4-5 GeV/c
  • Reduces effect of jet quenching

Do soft and hard partons recombine or just
softsoft ? Explore
correlations with leading baryons and mesons
53
v2 and coalescence model
STAR Preliminary
Hadronization via quark coalescence v2 of a
hadron at a given p? is the partonic v2 at p?/n
scaled by the of quarks (n).
AuAu ?sNN200 GeV
MinBias 0-80
  • Works for K0s, ? ?
  • v2s v2u,d 7

D. Molnar, S.A. Voloshin Phys. Rev. Lett. 91,
092301 (2003) V. Greco, C.M. Ko, P. Levai Phys.
Rev. C68, 034904 (2003) R.J. Fries, B. Muller,
C. Nonaka, S.A. Bass Phys. Rev. C68, 044902
(2003) Z. Lin, C.M. Ko Phys. Rev. Lett. 89,
202302 (2002)
54
Sampling the elephant
Different physics for different scales
Hydro
ReCo
pQCD
Results at each scale essential for understanding
RHIC
  • All evidence suggest RHIC creates a hot and
    dense
  • medium with partonic degrees of freedom.
  • Only just beginning to understand the rich
    physics of RHIC.
  • Lots more to come and much already on TAPE!

55
The STAR Collaboration
  • Argonne National Laboratory
  • Institute of High Energy Physics - Beijing
  • University of Birmingham
  • Brookhaven National Laboratory
  • California Institute of Technology
  • University of California, Berkeley
  • University of California Davis
  • University of California - Los Angeles
  • Carnegie Mellon University
  • Creighton University
  • Nuclear Physics Inst., Acad. Sciences
  • Lab. High Energy Physics - Dubna
  • Particle Physics Laboratory - Dubna
  • University of Frankfurt
  • Institute of Physics. Bhubaneswar
  • Indian Inst of Technology. Mumbai
  • Indiana University Cyclotron Facility
  • Institut de Recherches Subatomiques de Strasbourg
  • Kent State University
  • City College of New York
  • NIKHEF
  • Ohio State University
  • Panjab University
  • Pennsylvania State University
  • Inst High Energy Physics - Protvino
  • Purdue University
  • University of Rajasthan
  • Rice University
  • Inst. de Fisica Univ. de Sao Paulo
  • USTC
  • Shanghai Institue of Applied Physics
  • SUBATECH
  • Texas AM University
  • University of Texas - Austin
  • Tsinghua University
  • Valparaiso University
  • Variable Energy Cyclotron Centre. Kolkata
  • Warsaw University of Technology

  • Countries 12
  • Institutions 50
  • Collaborators 500

56
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