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Low-$p_{T}$ $\mu^{+}\mu^{-}$ pair production in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV at STAR

Not scheduled
15m
Oral report 3. 重离子物理

Speaker

Jian Zhou (University of Science and Technology of China)

Description

Recently, significant enhancements of $e^{+}e^{-}$ pairs at very low transverse momentum ($p_{T}$) were observed by the STAR collaboration in peripheral Au+Au collisions. The excess can be explained by photon-photon interactions induced by the extremely strong electromagnetic field produced by the fast-moving heavy ions. While such photon-photon interactions were traditionally studied in ultra-peripheral collisions without any nuclear overlaps, they could provide a novel probe to the Quark Gluon Plasma (QGP) created in peripheral collisions since the very-low-$p_{T}$ dileptons are produced in the early stage of the collisions. Furthermore, the photon-photon interactions could be used to probe the possible existence of a strong magnetic field trapped in a conducting QGP medium. Measurements of $\mu^{+}\mu^{-}$ pairs provide a complementary channel to investigate these phenomena. In 2014 and 2016, the STAR experiment at RHIC recorded large samples of Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. In this talk, we will present new measurements of invariant mass and yield distributions for $\mu^{+}\mu^{-}$ pair production at $p_{T} < 0.1$ GeV/$c$. The $p_{T}^{2}$ distribution of the excess yields will also be shown. Physics implications will be discussed together with model comparisons.

Primary author

Jian Zhou (University of Science and Technology of China)

Presentation materials