From Glasma to Plasma in Heavy Ion Collisions

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From Glasma to Plasmain Heavy Ion Collisions

• Raju Venugopalan
• Brookhaven National Laboratory

Topical Overview Talk, QM2008, Jaipur, Feb. 4th,
2008
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What is the Glasma ?
Ludlam, McLerran, Physics Today (2003)
Glasma (\Glahs-maa\) Noun non-equilibrium
matter between Color Glass Condensate (CGC)
Quark Gluon Plasma (QGP)
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Why is the Glasma relevant ?

• Intrinsic interest

Glasma fields are among strongest Electric
Magnetic fields in nature. What are their
properties ?
The Glasma is key to quantitative understanding
of matter produced in HI collisions
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Little Bang
Big Bang
Hot Era
WMAP data (3x105 years)
QGP
Inflation
CGC/ Glasma
Plot by T. Hatsuda
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Big Bang vs. Little Bang
Decaying Inflaton field with occupation 1/g2 Decaying Glasma field with occupation 1/g2
Explosive amplification of low mom. small fluctuations (preheating) Explosive amplification of low mom. small fluctuations (Weibel instability ?)
Interaction of fluct./inflaton - thermalization Interaction of fluct./Glasma - thermalization ?
Other common features topological defects,
turbulence ?
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Before the Little Bang

• Nuclear wavefunction at high energies

Bremsstrahlung
? ?SY

Recombination
Saturation
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Hadron wave-fns universal features
CGC Effective Theory classic fields strong
stochastic sources
?S(QS2) ltlt 1
T. Ullrich (see talk) -based on Kowalski, Lappi,
RV PRL 100, 022303 (2008)
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How is Glasma formed in a Little Bang ?

• Problem Compute particle production in field
• theories with strong time dependent sources

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Glasma dynamics
perturbative vs non-perturbative
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Systematic expansion for multiplicity moments
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Numerical Simulations of classical Glasma fields
Krasnitz, Nara, RV Lappi (see talk)
LO Glasma fields are boost invariant
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LO Glasma Multiplicity
I) RHIC
Au-Au mult. at eta0
Krasnitz, RV
Kharzeev, Levin, Nardi
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Flow in the Glasma (I)

• Large initial ET ? QS NCGC ? Nhad consistent
• with strong isentropic flow. Initial
  conditions for hydro

Hirano, Nara
CGC- type initial conditions leave room for
larger dissipation (viscosity) in hydro stage ?
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Flow in the Glasma (II)
Partial thermalization and v2 fluctuations
Bhalerao,Borghini, Blaizot,Ollitrault
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Flow in the Glasma (III)

• Whats the pre-thermal flow generated in the
  Glasma ?

Classical field
Classical field / Particle
Particle
f lt 1
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The unstable Glasma (I)
Kharzeev,Krasnitz,RV Lappi,McLerran

• LO boost invariant E B fields
• purely longitudinal for ? 0
• generate small amounts of topological charge

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The unstable Glasma (II)

• Small rapidity dependent quantum fluctuations of
  the
• LO Yang-Mills fields grow rapidly as

• E? and B? fields as large
• as EL and BL at time

Romatschke, RVPRL,PRD(2006)
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The unstable Glasma (III)
Romatschke, RV
Frequency of maximally unstable k? mode grows
rapidly
Large angle deflections of colored particles in
strong fields
(Numerical studies by Frankfurt group - C.
Greiner talk)
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Small fluctuation spectrum ab initio in the
Glasma multiplicity moments to NLO
Turbulent isotropization on short time scales ?
Arnold, Moore Mueller,Shoshi,Wong
Bödeker,Rummukainen
I) Anomalously low viscosityII) Large energy
loss of jets in strong fields ?
(talks by Majumder and Müller)
III) Explosive generation of P and CP odd
transitions via sphalerons (see Warringas
talk)
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Another example of a small fluctuation spectrum
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Multiplicity to NLO
(O(1) in g and all orders in (g?)n )
Gelis, RV

Gluon pair production
One loop contribution to classical field
Initial value problem with retarded boundary
conditions - can be solved on a lattice in real
time
(a la Gelis,Kajantie,Lappi for Fermion pair
production)
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NLO and QCD Factorization
Gelis,Lappi,RV
What small fluctuations go into wave fn. and
what go into particle production ?
Small x (JIMWLK) evolution of nucleus A -- sum
(?SY)n terms
Small x (JIMWLK) evolution of nucleus B ---sum
(?SY)n terms
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From Glasma to Plasma

• NLO factorization formula

• With spectrum, can compute T?? - and match to
• hydro/kinetic theory

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Ridgeology
Rudy Hwa (see talk) parallel session
Near side peak ridge (from talk by J.
Putschke,STAR collaboration)
Jet spectra
Ridge spectra
STAR preliminary
STAR preliminary
inclusive
inclusive
pt,assoc,cut
pt,assoc,cut
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Two particle correlations in the Glasma variance
at LO
Gelis, RV NPA 779 (2006), 177
Glasma sensitive to long range rapidity
correlations
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Our take on the Ridge
Gelis,Lappi,RV
i) Long range rapidity correlations built in at
early times because Glasma background field
is boost invariant. (These are the beam jets.)
ii) Rapidity correlations are preserved because
matter density dilutes rapidly along the beam
direction
iv) May explain why features of the ridge persist
for both soft and semi-hard associated particles
Need detailed models with realistic geometry
effects
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Conclusions

• I. Ab initio (NLO) calculations of the initial
  Glasma
• in HI collisions are becoming available
• II. Quantifying how the Glasma thermalizes
  strongly
• constrains parameters of the (near) perfect
  fluid
• III. Deep connections between QCD factorization
• and turbulent thermalization
• IV. Possible explanation of interesting
  structures
• from jetmedium interactions