Download presentation
Presentation is loading. Please wait.
Published byBruce Boyd Modified over 9 years ago
1
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
2
Brown-Rho scaling in normal nuclei J. W. Holt et al., PRL 100 (2008) 062501
3
D. Miller, Phys. Rept. 443 (2007) 55 Melting of Soft Glue and the Flash Temperature
4
Mesons at and above T c Degenerate SU(4) above T c Massless at T c H.-J. Park et al., NPA 774 (2006) 889 M. Asakawa et al., NPA 715 (2003) 863c
5
STAR 2004 Experiment Assuming equilibrium at freezeout: P. Braun-Munzinger et al., nucl-th/0304013 peripheral at Standard scenario: many generations HLS prediction: one generation J. Adams et al, PRL 92 (2004) 092301
6
HBT Stefan-Boltzmann law of radiation for massless bosons at T c Between T c and T flash hadrons propagate relatively freely Energy density at T equal defined as temperature at which mesons go back on-shell ’s ’s 1 fm to equilibrate
7
66 pions result at flash point 32 SU(4) Multiplet (massless at T c ) (18),a 0 (4),a 1 (27), (3), (2), = f 1285 (12) Hadronic Freedom (between T c and T flash ) G. Brown et al, PRC 74 (2006) 024906
8
S. Damjanovic, NA60 Claim: Brown-Rho scaling ruled out NA60 Dileptons
9
Dileptons as a probe for Brown-Rho scaling Not a good probe: (1) Hadronic freedom: mass-shifted mesons don’t decay until after T flash, where most mass regained (2) Violation of vector dominance: near T c dileptons produced independent of (3) Wave function suppression (4) Phase space suppression
10
S. Damjanovic, NA60 mass shifted most Blue shifted hadrons T eff ( ) 300 MeV
11
NA60 reconstruction of on-shell S. Damjanovic, NA60 T freezeout = 110 MeV Most ’s seen are just the on-shell vacuum ones
12
Role of the a 1 Number of on-shell ’s doubled at flash point a 1 goes on-shell at T flash Off-shell: cut down by factor ~ ¼
13
Low mass pion pairs
14
Summary: (1) Violation of vector dominance ~ ¼ suppression (2) Kinematical factor ~ ½ that for off-shell ’s compared to on-shell ones (3) Number of on-shell ’s doubled at flash point from decay of a 1 Mass shifted off-shell ’s suppressed by a factor of ~ 1/10 compared to on-shell ’s
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.