Dimuon production from in-medium rho decays from QCD sum rules

Abstract

We compute the dimuon-excess invariant mass distribution at the rho-meson peak in the context of relativistic heavy-ion collisions at SPS energies. The temperature, T, and chemical potential, mu, dependent parameters describing the rho-meson --its width, mass and leptonic decay constant-- are determined from finite energy QCD sum rules. Results show that the rho-meson width increases whereas its mass and leptonic decay constant decrease near the (chemical potential-dependent) critical temperature T_c(mu) for chiral symmetry restoration/quark-gluon deconfinement. As a consequence, starting from T_c(mu), for a short lived cooling the main effect is a broadening of the dimuon distribution. However, when the evolution brings the system to a lower freeze-out temperature, with the rho-meson parameters approaching their vacuum values, the dimuon distribution shows a broad peak centered at the vacuum rho-meson mass. For even lower freeze-out temperatures the peak becomes less prominent since the thermal phase space factor suppresses the distribution for larger values of the invariant dimuon mass, given that the average temperature is smaller. The dimuon distribution exhibits a non-trivial behavior with mu. For small mu values the distribution broadens with increasing mu becoming a bit steeper at low invariant masses for larger values of mu. Our results are in very good agreement with data from the NA60 Collaboration.

References in corpus (6)

• Evidence for the production of thermal muon pairs with masses above 1 GeV/c^2 in 158A GeV Indium-Indium Collisions
• NA60 results on thermal dimuons
• Evidence for radial flow of thermal dileptons in high-energy nuclear collisions
• Low mass dilepton production at ultrarelativistic energies
• Rho-meson resonance broadening in QCD at finite temperature
• Dilepton Measurements at STAR

Cited by in corpus (6)

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• Finite temperature sum rules in the vector channel at finite momentum
• Weinberg sum rules at finite temperature
• Relation between the continuum threshold and the Polyakov loop with the QCD deconfinement transition
• Hadronic matter at the edge: A survey of some theoretical approaches to the physics of the QCD phase diagram
• Finite-energy sum rules at finite chemical potential and zero temperature