Physical Review Letters
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.
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
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Bültmann, S.; Plyku, D.; and STAR Collaboration, "Dielectron Mass Spectra from Au plus Au Collisions at √ˢᴺᴺ = 200 GeV" (2014). Physics Faculty Publications. 183.