Speaker
Description
The deuteron carries baryon number two and is abundantly produced in the baryon-rich matter created in heavy-ion collisions. Its number fluctuations can provide insight into QCD matter at high baryon density and may be sensitive to critical-point physics. Since deuterons are formed from nucleons, their fluctuations are closely connected to baryon-density fluctuations and can complement conserved-charge cumulant measurements. Their dependence on rapidity acceptance can also help probe the range of the underlying correlations. In addition, deuteron cumulants and proton–deuteron correlations provide useful information on the production mechanism of light nuclei in heavy-ion collisions.
We report measurements of cumulants up to fourth order, factorial cumulants, and their ratios for deuteron number distributions, together with proton–deuteron mixed cumulants, in Au+Au collisions at $\sqrt{s_{NN}} = 3.0$ GeV FXT to 7.7 GeV BES-II collider energy at STAR. These measurements reach the high-$\mu_B$ region of the RHIC beam energy scan. Deuterons are identified using the Time Projection Chamber and Time-of-Flight detectors within $0.8 < p_T \,(\mathrm{GeV}/c) < 4.0$. The centrality and rapidity-acceptance dependence of deuteron cumulants and proton–deuteron mixed cumulants will be presented after corrections for detector efficiency and centrality bin-width effects. The results will be compared with thermal and coalescence model calculations, and their implications for baryon-number dynamics and the QCD phase diagram at high baryon density will be discussed.
