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Energy dependence of acceptance-corrected dielectron excess mass spectrum at mid-rapidity in Au$+$Au collisions at $\sqrt{s_{NN}} =$ 19.6 and 200 GeV

The STAR collaboration
Phys.Lett. B750 (2015) 64-71, 2015

Abstract (data abstract)
BNL-RHIC. The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity $|y_{ee}|<1$ in minimum-bias Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened $\rho$ spectral function for $M_{ee}<1.1$ GeV/$c^{2}$. The integrated dielectron excess yield at $\sqrt{s_{NN}}$ = 19.6 GeV for $0.4<M_{ee}<0.75$ GeV/$c^2$, normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in In+In collisions at $\sqrt{s_{NN}}$ = 17.3 GeV. For $\sqrt{s_{NN}}$ = 200 GeV, the normalized excess yield in central collisions is higher than that at $\sqrt{s_{NN}}$ = 17.3 GeV and increases from peripheral to central collisions. These measurements indicate that the lifetime of the hot, dense medium created in central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV is longer than those in peripheral collisions and at lower energies.

  • Table 1

    Data from Figure 1

    10.17182/hepdata.72236.v1/t1

    Reconstructed dielectron unlike-sign pairs, like-sign pairs and signal distributions, together with the signal to background ratio (S/B). All columns are...

  • Table 2

    Data from Figure 4

    10.17182/hepdata.72236.v1/t2

    Dielectron invariant mass spectrum in the STAR acceptance (|$y_{ee}$| < 1, 0.2 < $p_T^e$ < 3 GeV/c, |$\eta^e$ | <...

  • Table 3

    Data from Figure 4

    10.17182/hepdata.72236.v1/t3

    Hadronic cocktail consisting of the decays of light hadrons and correlated decays of charm in Au+Au collisions at $\sqrt{s_{NN}}$ =...

  • Table 4

    Data from Figure 5

    10.17182/hepdata.72236.v1/t4

    The acceptance-corrected excess dielectron mass spectra, normalized to the charged particle multiplicity at mid-rapidity dNch/dy, in Au+Au collisions at $\sqrt{s_{NN}}$...

  • Table 5

    Data from Figure 5

    10.17182/hepdata.72236.v1/t5

    The acceptance-corrected excess dielectron mass spectra, normalized to the charged particle multiplicity at mid-rapidity dNch/dy, in Au+Au collisions at $\sqrt{s_{NN}}$...

  • Table 6

    Data from Figure 6

    10.17182/hepdata.72236.v1/t6

    Integrated yields of the normalized dilepton excesses for 0.4 < $M^{ll}$ < 0.75 GeV/c$^2$ as a function of dNch/dy. From...

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