Transcript J-PARCでありうる将来 としての重イオン物理

J-PARCでありうる将来
としての重イオン物理
小沢 恭一郎
（東大・理）
2008/9/1
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(Thanks for
a talk by A. Ohnishi @ JPS02)
J-PARC as
a Dense QCD Lab
T
QGP
RHIC
~200MeV
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ρ０
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Neutron
Star
ρB
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Explore QCD phase
diagram
By A. Ohnishi
High density
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In addition, hadron properties can be measured in several QCD media.
RHICでの成功要因
• クォーク・グルーオン・プラズマの生成
• 衝突の初期状態の摂動論的な計算による決定
– Clearなプローブの設定
• 流体力学を用いた時間発展の解析
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系の温度・密度状態の時間発展の定量的評価が重要
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AGS dataの理解
Freeze out and hadron
cross sections are well
understood.
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Access to high density
Formed medium has a trajectory on a QCD phase.
Lepton & Photon
Rare Events / fluctuations
High Intensity is essential
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Hopeful measurements
• pT spectra of all particles
– Extend to higher pT region
– Now, we know hard probes have rich physics.
• Lepton & photon
– Direct access to high dense matter
– Mass modification of hadrons
– Thermal emission
• Event fluctuation and rare events
– High intensity beam is required
• Collective flows (related to EOS)
– Detailed study of pT and particle dependence
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Several difference QCD media are generated using
different energy
and
collision species.
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In addition, improved model calculations can be expected.
Interesting features
Strangeness enhancement @ J-PARC energy
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W. Cassing, E. Bratkovskaya, A. Sibirtsev, Nucl. Phys. A 691 (2001) 74
Charm production
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Collective flow
Direct Flow (dPx/dy)
Direct flow ~ 0
Smaller spectator-participant interaction
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Flow (II)
Radial Flow
Pressure history
Large Radial flow
 Large baryon density
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Quark condensates
Spontaneous breaking of a symmetry is marked by:
* a non-zero order parameter, the quark
 qq 
condensate <qq> in the case of QCD:
250MeV 3
 qq  0
High T
High 
メソン質量に対する予測
At Nuclear
Density
heavy ion reactions:
A+AV+X
mV(>>0;T>>0)
, G.E.Brown
. p - beams
and M. Rho,
SPS
RHIC
PRL 66 (1991) 2720
J-PARC elementary
*
reaction:
*
q
q
LEPS2 m
, p,   V+X
LHC
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J-PARCK.WS@RIKEN
NP08@Mito,
Ozawa
J-PARC Heavy-Ion
m

 0 .8     0 
qq
m
V(=0;T=0)
T.Hatsuda and S. Lee,
PRC 46 (1992) R34
m*V 
 
  1   B  ;   0.18
mV 
0 
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PREDICTED “SPECTRA”
• Situation is not so simple, several theories and
models predict spectral function of vector
mesons (, w, f).
F. Klingl et al. NPA 624 (1997) 527
– Lowering of in-medium mass
– Broadening of resonance
- meson
NPA 650 (1999) 299
w- meson
R. Rapp (Nucl. Phys A661(1999) 238c
高温・高密度に対する計算の例
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原子核密度に対する計算の例
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PREDICTED “SPECTRA”
(CONT’D)
M. Lutz et al. , Nucl. Phys. A 706 (2002) 431
P. Muehlich et al. , Nucl. Phys. A 780 (2006) 187

w
w
structure in spectral function due
to coupling to baryon resonances
structure due to coupling to
S11,P13 resonances
原子核中のバリオンとの結合を考慮に入れた例
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KEK E325, f  e+e- with p+A
Induce 12 GeV protons to Carbon and Cupper target, generate
vector mesons, and detect e+e- decays with large acceptance
spectrometer.
b<1.25 (Slow)
Cu
Invariant mass spectrum for
slow f mesons of Cu target
shows a excess at low mass
side of f.
Mass Shift:
mf = m0 (1 -  /0) for  = 0.03
Let’s go to
J-PARC!
100 times larger statistics
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J-PARC can accelerate
Heavy ions?
• According to Mori-san’s presentation
at NP02
– Main ring is OK
– Booster is questionable
– Alternative idea is using FFAG.
• Sorry, I forgot to update the
information.
– I expect inputs from other people.
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FAIR
•
•
•
•
2007 start of project
2012 first experiment
2015 completion
Their R&D for detectors and
accelerators are well performed.
• BUT, we have an accelerator!!
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Summary
• Heavy ion collisions at J-PARC can
explore QCD phase diagram.
• Several interesting measurements
are remaining, even after AGS.
– Equation of state at high density matter
– Critical end point
– Hadron mass and chiral symmetry
• Why don’t we accelerate heavy ions
at J-PARC?
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Back ups
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Taken from T. Hatsuda’s slide
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Taken from T. Hatsuda’s slide
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