Introduction to Relativistic Heavy Ion Collision Physics

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Introduction to Relativistic Heavy Ion Collision
Physics

• Huan Z. Huang
• ???
• Department of Physics and Astronomy
• University of California, Los Angeles

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Two Puzzles of Modern Physics
-- T.D.Lee ???

• Missing Symmetry all present theories are based
  on symmetry, but most symmetry quantum numbers
  are NOT conserved.
• Unseen Quarks all hadrons are made of quarks,
  yet NO individual quark has been observed.

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Vacuum As A Condensate

• Vacuum is everything but empty!
• The complex structure of the vacuum and the
  response of the vacuum to the physical world
  breaks the symmetry.
• Vacuum can be excited!

We do not understand vacuum at all !
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A Pictorial View of Micro-Bangs at RHIC
Huge Stretch Transverse Expansion High
Temperature (?!)
Nuclei pass thru each other lt 1 fm/c
Thin Pancakes Lorentz g100
The Last Epoch Final Freezeout-- Large Volume
AuAu Head-on Collisions ? 40x1012 eV 6
micro-Joule Human Ear Sensitivity 10-11 erg
10-18 Joule A very loud Bang, indeed, if E?
Sound
Vacuum Engineering !
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High Energy Nucleus-Nucleus Collisions
Physics 1) Parton distributions in nuclei 2)
Initial conditions of the collision 3) a new
state of matter Quark-Gluon Plasma and its
properties 4) hadronization
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RHIC Complex
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Relativistic Heavy Ion Collider --- RHIC
AuAu 200 GeV N-N CM energy Polarized pp up to
500 GeV CM energy
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Salient Feature of Strong Interaction
Asymptotic Freedom Quark
Confinement
????? 300 B.C. ????,????,????
Take half from a foot long stick each day, You
will never exhaust it in million years.
QCD
Quark pairs can be produced from vacuum No free
quark can be observed
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QCD on Lattice
Transition from quarks to hadrons DOF ! QGP
not an ideal Boltzmann gas !
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Lattice current status

• technical progress finer mesh size, physical
  quark masses, improved fermion actions
• phase-transition smooth, rapid cross-over
• EoS at finite µB in reach, but with large
  systematic uncertainties
• critical temperature TC?180 MeV

Fodor Katz, hep-lat/0110102
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Quark-Hadron Phase Transition
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The Melting of Quarks and Gluons-- Quark-Gluon
Plasma --
Matter Compression Vacuum Heating
Deconfinement
High Temperature Vacuum -- high energy heavy
ion collisions -- the Big Bang
High Baryon Density -- low energy heavy ion
collisions -- neutron star?quark star
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Collision Dynamics
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Initial Energy Density Estimate
PRL 85, 3100 (00) 91, 052303 (03) 88, 22302
(02), 91, 052303 (03)
200 GeV
130 GeV
PHOBOS
19.6 GeV
Pseudo-rapidity
Within hlt0.5 the total transverse momentum
created is 1.5x650x0.508 500 GeV from an
initial transverse overlap area of pR2 153
fm2 !
hminus Central AuAu ltpTgt0.508GeV/c pp
0.390GeV/c
Energy density e 5-30 e0 at early time
t0.2-1 fm/c !
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Ideas for QGP Signatures
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Ideas for QGP Signatures
Chiral Symmetry Restoration T 0, m(u,d,s)
gt 0 Spontaneous symmetry breaking Tgt 150
MeV, m0 Chiral symmetry restored Mass,
width and decay branching ratios of resonances
may be different in dense medium .
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The STAR Detector
1st year detectors
2nd year detectors
installation in 2002
installation in 2003
Coils
TPC Endcap MWPC
Silicon Vertex Tracker
Silicon Strip Detector
ZDC
ZDC
Vertex Position Detectors
Barrel EM Calorimeter
Central Trigger Barrel
TOF