The charm quark spectrum that was input as a normalized form f c (p T ) = (1.0 + 3.185p 2 T ) −2.7 /0.354 is extracted by fitting the STAR spectra of D 0 (D 0 ) and electron. The fitted spectra in Fig. 1 are slightly softer than the STAR **data** considering no bottom contributions. The solid lines are from the STAR σ NN cc , while the dashed lines, all lower than the data, correspond to the PHENIX σ NN cc = 0.622 mb [31]. Hereafter, the STAR σ NN cc 1.4 mb is used in all calculations at 200 GeV. The p T dependencies of the charm baryon-to-meson ratios Fig. 2. It is clear to see that the charm baryon enhancement in intermediate p T range is very prominent, which is similar to that of the p/π ratio. Note that the peak of
Λ c +Λ c D 0 +D 0 , Λ c +Λ c D + +D − , and Λ c +Λ c D + s +D − s are plotted inΛ c +Λ c D + +D − is even higher than Λ c +Λ c D + s +D − s . This is because the yield of D + s (D − s ) is larger than D + (D − ) around p T = 3
GeV/c due to the decay effect. The shapes of the p T dependencies of these ratios are dependent on the CO/RE mechanism, decay effect, and the charm quark spectrum obtained from fitting **data** shown in Fig. 1. Comparing with the **data** of p/π + [34] in the same Au+Au collisions, one can see that all peaks broaden and shift to the right because essentially the spectrum of the charm quark is much harder than that of the u(d) quark.