${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}$ production and characterization in Cu + Cu collisions at $\sqrt{s_{NN}}=200$ GeV

Production of the (anti)hypertriton nuclei ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}$ and ${}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}$ in Cu+Cu interactions at $\sqrt{s_{NN}}=200$ GeV is studied in three centrality bins of 0–10%, 10–30%, and 30–60% using the dynamically constrained phase-space coalescence model together with paciae model simulations. They are compared with ${}^3\mathrm{H}\left({}^3\overline{\mathrm{H}}\right)$ and ${}^3\mathrm{He}\left({}^3\overline{\mathrm{He}}\right)$ nuclei. It is indicated by the study that the yields of light nuclei and hypernuclei increase rapidly from peripheral to central collisions while their antiparticle-to-particle ratios remain unchanged for different centrality bins. The strangeness population factor $S_3=({}_{\mathrm{\Lambda }}{}^3\mathrm{H}/{}^3\mathrm{He})/(\mathrm{\Lambda }/p)$ was found to be close to unity, and was compatible with the STAR data and theoretical model calculations, suggesting that the phase-space population of strange quarks is similar to the ones of light quarks and the creation of deconfined high-temperature quark matter in Cu+Cu collisions.

Figure 1

The transverse momentum spectra of $p$ (upper panel) and $\mathrm{\Lambda }$ (lower panel) in Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV for different centrality bins of 0–10%, 10–30%, and 30–60%. The open squares show the results of paciae model, and the filled circles show the STAR data [18, 19].

Figure 2

Logarithmic distribution of the integrated yields $dN/dy$ of nuclei ${}_{\mathrm{\Lambda }}{}^3\mathrm{H}, {}^3\mathrm{He}, {}^3\mathrm{H}$ and their antinuclei, as a function of $\mathrm{\Delta }m$ with $\left|\eta \right|<0.5$ and $0<p_T<6$ GeV/$c$. For clarity, data of nuclei and antinuclei are purposely separated by powers of 10.

Figure 3

The distribution of ratios ${}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}/{}_{\mathrm{\Lambda }}{}^3\mathrm{H}, {}^3\overline{\mathrm{He}}/{}^3\mathrm{He}$, and ${}^3\overline{\mathrm{H}}/{}^3\mathrm{H}$ versus the mass uncertainty ($\mathrm{\Delta }m$) in Cu+Cu collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}\left(\right|\eta |<0.5$ and $0<p_T<6$ GeV/$c$). Error bars are statistical only.

Figure 4

The ratios ($\overline{p}/p, \overline{\mathrm{\Lambda }}/\mathrm{\Lambda }, {}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}/{}_{\mathrm{\Lambda }}{}^3\mathrm{H}, {}^3\overline{\mathrm{He}}/{}^3\mathrm{He}, {}^3\overline{\mathrm{H}}/{}^3\mathrm{H}$) and ($p/\mathrm{\Lambda }, \overline{\mathrm{\Lambda }}/\overline{p}, {}_{\mathrm{\Lambda }}{}^3\mathrm{H}/{}^3\mathrm{He}, {}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}/{}^3\overline{\mathrm{He}}, {}_{\mathrm{\Lambda }}{}^3\mathrm{H}/{}^3\mathrm{H}, {}_{\overline{\mathrm{\Lambda }}}{}^3\overline{\mathrm{H}}/{}^3\overline{\mathrm{H}}$) determined by the paciae+dcpc model analysis (open squares) for matter and antimatter compared with STAR results (filled circles) [4]. Here, statistical and systematic errors are represented by error bars and error boxes, respectively.

Figure 5

The $S_3\left({\overline{S}}_3\right)$ ratio as a function of the centrality in Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV. For comparison, the data from STAR Au+Au 0–80% collisions at $\sqrt{s_{NN}}=200$ GeV [4] and minimum bias Au+Au collisions from the melting AMPT plus coalescence model calculation [42] are shown here. Statistical uncertainties are represented by bars.