Signals of quark combination at hadronization in $pp$ collisions at $\sqrt{s}=200$ GeV

Abstract: We find signals of quark combination at hadronization from the experimental data of $p_{T}$ spectra of hadrons at mid-rapidity in $pp$ collisions at $\sqrt{s}=200$ GeV. The first is the constituent quark number scaling property for $p_{T}$ spectra of $\Omega^{-}$ and $\phi$ and that for $p_{T}$ spectra of $p$ and $\rho^{0}$. The second is that $p_{T}$ spectra of $\Lambda$, $\Xi^{-}$, and $K^{*0}$ can be self-consistently described using the spectrum of strange quarks from $\phi$ data and that of up/down quarks from $p$ data in the equal-velocity combination mechanism. The third is that experimental data for $p_{T}$ spectrum of $D^{*+}$ are also well described using the spectrum of up/down quarks from $p$ data and that of charm quarks from perturbative QCD calculations. These results indicate a similarity between hadron production in $pp$ collisions at $\sqrt{s}=200$ GeV and that at LHC energies. We predict $p_{T}$ spectra of single-charm hadrons and their spectrum ratios. We suggest systematic measurements in $pp$ collisions at $\sqrt{s}=200$ GeV in future so as to better understand the property of small parton system created in $pp$ collisions at different collision energies.