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A Hidden Local Symmetry Theory of Dileptons in Relativistic Heavy Ion Collisions

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.

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A Hidden Local Symmetry Theory of Dileptons in Relativistic Heavy Ion Collisions

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  1. 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

  2. Brown-Rho scaling in normal nuclei J. W. Holt et al., PRL 100 (2008) 062501

  3. Melting of Soft Glue and the Flash Temperature D. Miller, Phys. Rept. 443 (2007) 55

  4. Mesons at and above Tc • Degenerate SU(4) above Tc M. Asakawa et al., NPA 715 (2003) 863c • Massless at Tc H.-J. Park et al., NPA 774 (2006) 889

  5. STAR 2004 Experiment J. Adams et al, PRL 92 (2004) 092301 peripheral at Assuming equilibrium at freezeout: P. Braun-Munzinger et al., nucl-th/0304013 • Standard scenario: many generations • HLS prediction: one generation

  6. HBT • Between Tc and Tflash hadrons propagate relatively freely defined as temperature at which mesons go back on-shell • Stefan-Boltzmann law of radiation for massless bosons at Tc ’s ’s • Energy density at Tequal • 1 fm to equilibrate

  7. Hadronic Freedom (between Tc and Tflash) G. Brown et al, PRC 74 (2006) 024906 32 SU(4) Multiplet (massless at Tc) (18),a0(4),a1(27),(3),(2), =f1285(12) 66 pions result at flash point

  8. NA60 Dileptons Claim: Brown-Rho scaling ruled out S. Damjanovic, NA60

  9. 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  (3) Wave function suppression (4) Phase space suppression

  10. Blue shifted hadrons •  mass shifted most • Teff()  300 MeV S. Damjanovic, NA60

  11. NA60 reconstruction of on-shell Tfreezeout = 110 MeV • Most ’s seen are just the on-shell vacuum ones S. Damjanovic, NA60

  12. Role of the a1 • a1 goes on-shell at Tflash • Number of on-shell ’s doubled at flash point • 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 a1 • Mass shifted off-shell ’s suppressed by a factor of ~ 1/10 compared to on-shell ’s

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