Deuteron and Antideuteron Production in $\mathrm{Au}+\mathrm{Au}$ Collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$

The production of deuterons and antideuterons in the transverse momentum range $1.1<p_T<4.3\mathrm{GeV}/c$ at midrapidity in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of $p_T$, which is consistent with an expanding collision zone. Comparing (anti)proton yields, $\overline{p}/p=0.73\pm 0.01$, with (anti)deuteron yields, $\overline{d}/d=0.47\pm 0.03$, we estimate that $\overline{n}/n=0.64\pm 0.04$. The nucleon phase space density is estimated from the coalescence measurement.

Figure 1

Histograms of the mass squared for identified antideuterons in the transverse momentum range $1.1<p_T<3.5\mathrm{GeV}/c$ (in $400\mathrm{MeV}/c$ increments), with Gaussian fits including an exponential background.

Figure 2

Corrected spectra for deuterons (left panel) and antideuterons (right panel) for different centralities are plotted vs $m_T$. Error bars indicate statistical errors and gray bands the systematic errors. Values are plotted at the “true” mean value of $m_T$ of each bin, the extent of which is indicated by the width of the gray bars along the $x$ axis.

Figure 3

Coalescence parameter $B_2$ vs $p_T$ for deuterons (left panel) and antideuterons (right panel). Gray bands indicate the systematic errors. Values are plotted at the true mean value of $p_T$ of each bin, the extent of which is indicated by the width of the gray bars along the $x$ axis.

Figure 4

Comparison of the coalescence parameter for deuterons and antideuterons ($p_T=1.3\mathrm{GeV}/c$) with other experiments at different values of $\sqrt{s}$.

Figure 5

Average nucleon phase space density as a function of $p_T$ for central collisions. Solid circles correspond to nucleons and open circles correspond to antinucleons. The curves are fits to a Boltzmann function, $C\exp (-m_T/T)$, with $T=568\pm 96\mathrm{MeV}$ (nucleons) and $T=670\pm 182\mathrm{MeV}$ (antinucleons).