Measurement of Sequential ϒ Suppression in Au+Au Collisions at sNN=200 GeV with the STAR Experiment

Le résumé fourni par la source

We report on measurements of sequential $\mathrm{\ensuremath{\Upsilon}}$ suppression in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=200\text{ }\text{ }\mathrm{GeV}$ with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%--60% centrality class, the nuclear modification factors (${R}_{AA}$), which quantify the level of yield suppression in heavy-ion collisions compared to $p+p$ collisions, for $\mathrm{\ensuremath{\Upsilon}}(1S)$ and $\mathrm{\ensuremath{\Upsilon}}(2S)$ are $0.40\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{sys})\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{norm})$ and $0.26\ifmmode\pm\else\textpm\fi{}0.08(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.02(\mathrm{sys})\ifmmode\pm\else\textpm\fi{}0.06(\mathrm{norm})$, respectively, while the upper limit of the $\mathrm{\ensuremath{\Upsilon}}(3S)$ ${R}_{AA}$ is 0.17 at a 95% confidence level. This provides experimental evidence that the $\mathrm{\ensuremath{\Upsilon}}(3S)$ is significantly more suppressed than the $\mathrm{\ensuremath{\Upsilon}}(1S)$ at RHIC. The level of suppression for $\mathrm{\ensuremath{\Upsilon}}(1S)$ is comparable to that observed at the much higher collision energy at the Large Hadron Collider. These results point to the creation of a medium at RHIC whose temperature is sufficiently high to strongly suppress excited $\mathrm{\ensuremath{\Upsilon}}$ states.

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