Measurement of the transverse-momentum fraction of strange hadrons from jet-like correlation structures in pp collisions at $\sqrt{s} = 13$ TeV

TL;DR

This paper presents the first measurements of the average transverse-momentum fraction of strange hadrons in pp collisions at 13 TeV, revealing different hadronization behaviors for mesons and baryons and challenging current Monte Carlo models.

Contribution

It introduces a novel method to measure the transverse-momentum fraction of strange hadrons using angular correlations in pp collisions at 13 TeV.

Findings

Flat trend for strange mesons' $raket{z}$ as a function of $p_T$.

Decreasing trend for strange baryons' $raket{z}$ with increasing $p_T$.

Current Monte Carlo models do not accurately reproduce the measured $raket{z}$ distributions.

Abstract

The first measurements of the average transverse-momentum fraction ($\langle z \rangle$) as a function of transverse momentum ($p_{\rm T}$) for strange baryons ($\Lambda$ and $\bar{\Lambda}$) and strange mesons ($K_{\rm S}^0$), produced in mini-jets defined through angular correlations in pp collisions at $\sqrt{s} = 13$ TeV, are reported by the ALICE Collaboration at the LHC. The observable is obtained using a novel method, where the angular correlation between the strange hadrons and inclusive charged hadrons is weighted by the $p_{\rm T}$ of correlated particles at small angular distance. As a function of strange particles' $p_{\rm T}$, the results reveal a flat trend for strange mesons and a decreasing trend for strange baryons in the measured $p_{\rm T}$ region, indicating distinct hadronization mechanisms for $K_{\rm S}^0$ and $\Lambda$($\bar{\Lambda}$). The measurements are compared to Monte Carlo models, namely PYTHIA~8 (with both Monash and Color Rope tunes) and the AMPT (A Multi-Phase Transport) model with string melting. None of these models provides a satisfactory description of the $\langle z \rangle$ distributions at low and intermediate $p_{\rm T}$.