Baryon enhancement in jets

TL;DR

This paper reports a simulated baryon enhancement in high-energy proton-proton collisions, suggesting a transition from quark to gluon jets, challenging existing medium-formation interpretations.

Contribution

It presents the first simulation-based observation of baryon enhancement in jets at high transverse momentum in pp collisions.

Findings

Baryon enhancement observed in PYTHIA8 simulations at high jet $p_T$

Transition from quark to gluon jets explains the effect

Challenges the medium-formation interpretation of baryon enhancement

Abstract

The enhancement of the baryon production relative to mesons in small-collision systems is considered a breakthrough result of the Large Hadron Collider since a similar effect in heavy-ion collisions is understood by invoking the formation of the strongly-interacting quark--gluon plasma. In this letter, a baryon enhancement is reported for $p_{\rm T}^{\rm ch,\, jet}>15$\,GeV/$c$ jets produced in pp collisions at $\sqrt{s}=13$\,TeV simulated with PYTHIA8. The effect can be explained as a transition between quark-initiated jets (low jet multiplicities) to gluon-initiated jets (high jet multiplicities). The present result challenges the interpretation about the multiplicity dependence of the baryon enhancement in terms of collective expansion of the medium and quark recombination.