Dilepton production from a viscous QGP

✍ Scribed by Kevin Dusling; Shu Lin

• Book ID: 103866427
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 498 KB
• Volume: 809
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/j.nuclphysa.2008.06.007

✦ Synopsis

This work calculates the first correction to the leading order q q dilepton production rates due to shear viscosity in an expanding gas. The modified rates are integrated over the space-time history of a viscous hydrodynamic simulation of RHIC collisions. The net result is a hardening of q ⊥ spectrum with the magnitude of the correction increasing with invariant mass. We argue that a thermal description is reliable for invariant masses less than M max ≈ (2τ 0 T 2 0 )/(η/s). For reasonable values of the shear viscosity and thermalization time M max ≈ 4.5 GeV. Finally, the early emission from a viscous medium is compared to emission from a longitudinally free streaming plasma. Qualitative differences in q ⊥ spectrum are seen which could be used to extract information on the thermalization time, viscosity to entropy ratio and possibly the thermalization mechanism in heavy-ion collisions.