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A Hidden Local Symmetry Theory of Dileptons in Relativistic Heavy Ion Collisions. Gerry Brown*. State University of New York. *G. E. Brown, M. Harada, J. W. Holt, M. Rho, C. Sasaki http://www.arXiv.org/abs/0804.3196. 4/25/08. Brown-Rho scaling in normal nuclei. - PowerPoint PPT Presentation
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A Hidden Local Symmetry Theory of Dileptons in Relativistic Heavy
Ion Collisions
Gerry Brown*
4/25/08
State University of New York
*G. E. Brown, M. Harada, J. W. Holt, M. Rho, C. Sasaki http://www.arXiv.org/abs/0804.3196
Brown-Rho scaling in normal nucleiJ. W. Holt et al., PRL 100 (2008) 062501
D. Miller, Phys. Rept. 443 (2007) 55
Melting of Soft Glue and the Flash Temperature
aa GG
g
gTG
2
)()(2
Mesons at and above Tc
• Degenerate SU(4) above Tc
• Massless at Tc H.-J. Park et al., NPA 774 (2006) 889
M. Asakawa et al., NPA 715 (2003) 863c
STAR 2004 Experiment
.)(syst037.0(stat)003.0169.00
Assuming equilibrium at freezeout:
40
104
P. Braun-Munzinger et al., nucl-th/0304013
.)(syst027.0(stat)001.0183.00
AuAu peripheral at
GeV200NNs
pp
AuAu
• Standard scenario: many generations• HLS prediction: one generation
J. Adams et al, PRL 92 (2004) 092301
HBT
3
42
)(1514
)(
c
T
V
TE c
• Stefan-Boltzmann law of radiation for massless bosons at Tc
equalT
1.3)(
)(3
flash
c
c
flash
T
T
TV
TV
• Between Tc and Tflash hadrons propagate relatively freely
3
42
)(152
1657)(
c
T
V
TE equalequal
• Energy density at Tequal
defined as temperature at which mesons go back on-shell
’s ’s
MeV13879.073
28)()(
4/1
equal
equal
ccequal T
T
TTETE
• 1 fm to equilibrate
2*3*
5**
g
g
m
m
66 pions result at flash point
32 SU(4) Multiplet (massless at Tc)
(18),a0(4),a1(27),(3),(2),
=f1285(12)
16.0)322(
30
Hadronic Freedom
freezeoutflash TT
(between Tc and Tflash)G. Brown et al, PRC 74 (2006) 024906
S. Damjanovic, NA60
Claim:
Brown-Rho scaling ruled out
NA60 Dileptons
Dileptons as a probe for Brown-Rho scaling
Not a good probe:
(1) Hadronic freedom: mass-shifted mesons don’t decay until after Tflash, where most mass regained(2) Violation of vector dominance: near Tc dileptons produced independent of
ea
g
21
1a
(3) Wave function suppression
(4) Phase space suppression
2)0(
S. Damjanovic, NA60
• mass shifted most
Blue shifted hadrons
• Teff() 300 MeV
TTT
Teff
1
1
NA60 reconstruction of on-shell
S. Damjanovic, NA60
Tfreezeout = 110 MeV
• Most ’s seen are just the on-shell vacuum ones
Role of the a1
• Number of on-shell ’s doubled at flash point
• a1 goes on-shell at Tflash
• Off-shell: cut down by factor ~ ¼
Low mass pion pairs
Summary:
(1) Violation of vector dominance ~ ¼ suppression(2) Kinematical factor ~ ½ that for off-shell ’s compared to on-shell ones
2)0(
(3) Number of on-shell ’s doubled at flash point from decay of a1
• Mass shifted off-shell ’s suppressed by a factor of ~ 1/10 compared to on-shell ’s