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Physical Review Letters






(022301) 1-7


We report the STAR measurements of dielectron (e+e-) production at midrapidity ( |yee| < 1) in Au + Au collisions at √ˢᴺᴺ = 200 GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 (ρ-like), 0.76-0.80 (ω-like), and 0.98-1.05 (ɸ-like) GeV/c2. The spectrum in the ω-like and ɸ-like regions can be well described by the hadronic cocktail simulation. In the ρ-like region, however, the vacuum ρ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77 ±0.11(stat) ± 0.24(syst) ± 0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the ρ meson. The excess yield in the ρ-like region increases with the number of collision participants faster than the ω and ɸ yields. Theoretical models with broadened rho contributions through interactions with constituents in the hot QCD medium provide a consistent description of the dilepton mass spectra for the measurement presented here and the earlier data at the Super Proton Synchrotron energies.


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Original Publication Citation

Adamczyk, L., Adkins, J. K., Agakishiev, G., Aggarwal, M. M., Ahammed, Z., Alekseev, I., . . . Zyzak, M. (2014). Dielectron mass spectra from Au plus Au collisions at √ˢᴺᴺ =200 GeV. Physical Review Letters, 113(2), 022301. doi:10.1103/PhysRevLett.113.022301

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