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

TL;DR

This paper presents evidence of quark combination signals in $pp$ collisions at 200 GeV, demonstrating constituent quark number scaling and successfully describing various hadron spectra, indicating similarities with higher energy collisions.

Contribution

It provides the first detailed analysis of quark combination signals in $pp$ collisions at this energy, using experimental data to support constituent quark scaling and spectrum descriptions.

Findings

Constituent quark number scaling observed in hadron spectra.

Spectra of various hadrons can be described using quark spectra from data.

Predictions made for charm hadron spectra and ratios.

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.