Constituent quark number scaling from strange hadron spectra in $pp$ collisions at $\sqrt{s}=$ 13 TeV

Abstract

We show that the data of $p_T$ spectra of $\hat{I}{\text{c◯}}^{-}$ and $\ddot{I}•$ at midrapidity in inelastic events in $pp$ collisions at $\sqrt{s}=$ 13 TeV exhibit a constituent quark number scaling property, which is a clear signal of quark combination mechanism at hadronization. We use a quark combination model under equal velocity combination approximation to systematically study the production of identified hadrons in $pp$ collisions at $\sqrt{s}$= 13 TeV. The midrapidity data of $p_T$ spectra of proton, $\hat{I}›$, $\hat{I}{ž}^{-}$, $\hat{I}{\text{c◯}}^{-}$, $\ddot{I}•$ and $K^{\ast }$ in inelastic events are simultaneously well fitted by the model. The data of multiplicity dependency of yields of these hadrons are also well understood. The strong $p_T$ dependence for data of $p/\ddot{I}•$ ratio is well explained by the model, which further suggests that the production of two hadrons with similar masses is determined by their quark contents at hadronization. $p_T$ spectra of strange hadrons at midrapidity in different multiplicity classes in $pp$ collisions at $\sqrt{s}=$ 13 TeV are predicted to further test the model in the future. The midrapidity $p_T$ spectra of soft ($p_T<2$ GeV/c) strange quark and up/down quark at hadronization in $pp$ collisions at $\sqrt{s}=$ 13 TeV are extracted.

13 pages, 14 figures