Energy dependence of pbar/p ratio in p+p collisions

TL;DR

This study compiles and compares experimental pbar/p ratios in p+p collisions across a wide energy range with various theoretical models, revealing model strengths, the impact of baryon production mechanisms, and differences between p+p and A+A collisions.

Contribution

It provides a comprehensive comparison of experimental data with models and explores baryon production mechanisms, including tuning parameters in PYTHIA to match observations.

Findings

PHOJET best matches experimental data with default settings.

PYTHIA requires tuning of diquark suppression for better agreement.

Baryon production is higher in A+A collisions than in p+p at energies below 200 GeV.

Abstract

We have compiled the experimentally measured pbar/p ratio at midrapidity in p+p collisions from \sqrt{s} = 23 to 7000 GeV and compared it to various mechanisms of baryon production as implemented in PYTHIA, PHOJET and HIJING/B-Bbar models. For the models studied with default settings, PHOJET has the best agreement with the measurements, PYTHIA gives a higher value for \sqrt{s} < 200 GeV and the ratios from HIJING/B-Bbar are consistently lower for all the \sqrt{s} studied. Comparison of the data to different mechanisms of baryon production as implemented in PYTHIA shows that through a suitable tuning of the suppression of diquark-antidiquark pair production in the color field relative to quark-antiquark production and allowing the diquarks to split according to the popcorn scheme gives a fairly reasonable description of the measured pbar/p ratio for \sqrt{s} < 200 GeV. Comparison of the beam energy dependence of the pbar/p ratio in p+p and nucleus-nucleus (A+A) collisions at midrapidity shows that the baryon production is significantly more for A+A collisions relative to p+p collisions for \sqrt{s} < 200 GeV. We also carry out a phenomenological fit to the y_beam dependence of the pbar/p ratio.