中国物理学会高能物理分会第十一届全国会员代表大会暨学术年会

Dielectrons are excellent probes of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. Because they can be produced at all stages of the collision system evolution and do not interact with the medium strongly, dielectrons carry the information from the initial stage to the final stage. In the low mass region ($\rm{ M_{ee} < M_{\phi} }$), the mass spectra of vector mesons will be modified by the hot and dense medium which is related to the chiral symmetry restoration in the medium. In the intermediate mass region ($\rm{M_{\phi} < M_{ee} < M_{J/\psi}}$), QGP thermal radiation can be used as a QGP thermometer. However, it is complicated to measure the QGP thermal radiation because of the heavy flavor semi-leptonic decay contributions. In this presentation, the result of the dielectron measurement in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}} = $ 54.4 GeV at STAR will be presented. With a 10 times larger data sample than that at 62 GeV from the first phase of the STAR Beam Energy Scan (BES-I) the program, the dielectron spectra can be studied with better precision. Furthermore, the physics implications of these measurements will be discussed.