J. Ruppert Hot Quarks 2006, May 2006 What does the rho? Lessons from NA60's di-muon measurement. Jörg Ruppert Nuclear Theory, Department of Physics, Duke University, Durham, NC, USA In collaboration with: Thorsten Renk Department of Physics, University of Jyväskylä, Jyväskylä, Finland
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J. RuppertHot Quarks 2006, May 2006 What does the rho? Lessons from NA60's di-muon measurement. Jörg Ruppert Nuclear Theory, Department of Physics, Duke.
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J. Ruppert Hot Quarks 2006, May 2006
What does the rho? Lessons from NA60's di-muon measurement.
Jörg RuppertNuclear Theory, Department of Physics,
Duke University, Durham, NC, USA
In collaboration with:
Thorsten RenkDepartment of Physics,
University of Jyväskylä, Jyväskylä, Finland
J. Ruppert Hot Quarks 2006, May 2006
Outline
1. Introduction: EM Probes of strongly interacting matter
On top of that non-thermal sources (hadron decays, Drell-Yan, open charm etc.)
J. Ruppert Hot Quarks 2006, May 2006
E. M. correlator in vacuumE. M. correlator in vacuum
Continuum
V
Vector meson dominance
Rho-meson dominant!
Compilation from Rapp, Wambach,
Adv.Nucl.Phys.25:1,2000
J. Ruppert Hot Quarks 2006, May 2006
Chiral symmetry breakingChiral symmetry breaking
Chiral symmetry spontanously broken in vacuum! Chiral partners in the hadronic spectrum split. Hot and dense matter excites the vacuum:Gradual restoration of chiral symmetry => Chiral partners become degenerate!
Systematic resummation scheme of certain classes of diagrams:Many-Body calculation that includes non-perturbative broadening effects due toa finite width of the pion. Ruppert, Renk, Phys.Rev.C71:064903,2005
approximation Self-energies
• Included: finite broadening• Not-included: mass shifts (disregard changes in the real part of the self-energy)
Compilation of calculations for the dilepton spectrum at CERES for different models of in-medium modifications. One fireball evolution model for all spectral functions Renk,Ruppert, Phys.Rev.C71:064903,2005.
Since no freeze-out analysis is available the Pb-Pb collisionmodel is rescaled!The choice of the decoupling temperature TF=130 MeV is not strongly restricted. This translates primarily into an uncertainty in the normalization of the final result.
J. Ruppert Hot Quarks 2006, May 2006
Comparison with NA60Comparison with NA60
pt>1 GeVpt<0.5 GeV
Pt integrated
J. Ruppert Hot Quarks 2006, May 2006
From In-In to Pb-Pb!From In-In to Pb-Pb!
pt<0.5 GeV
Pt integrated
pt>1 GeV
J. Ruppert Hot Quarks 2006, May 2006
What dominates M>1 GeV? QGP vs. low T
four pion annihilation?
What dominates M>1 GeV? QGP vs. low T
four pion annihilation?
van Hees, Rapp, hep-ph/0603084
Low T contributions would be significant due to fugacity !
Is such a description valid down to Tf?
Is chiral mixing effective at low T?Can low T contributions account for NA60’s pt cuts (next slide)?