Main Image
Volume 345 - International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (HardProbes2018) - Electroweak Probes
Low-$p_{\rm T}$ $e^+e^-$ pair production in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV and U+U collisions at $\sqrt{s_{\rm NN}}$ = 193 GeV at STAR
S. Yang* on behalf of the STAR collaboration
*corresponding author
Full text: pdf
Pre-published on: 2019 April 23
Published on: 2019 April 24
We present the first measurement of $e^+e^-$ pair production at $p_T$ < 0.15 GeV/$c$ in Au$+$Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{\rm NN}}$= 193 GeV with the STAR experiment. Significant enhancement with respect to known hadronic contributions is observed in the 40-80% centrality class of these collisions. The yield excess peaks distinctly at low $p_T$ with a width ($\sqrt{\langle p^2_T\rangle}$) between 40 and 60 MeV/$c$. Model calculations of photon-photon interaction describe the observed excess yields but fail to reproduce the $p^{2}_{T}$ distributions.
Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.