Insight into particle production mechanisms via angular correlations of identified particles in pp collisions at $\sqrt{s}=7$ TeV

TL;DR

This study investigates angular correlations of identified particles in 7 TeV proton-proton collisions, revealing unexpected anti-correlation patterns for baryon pairs that challenge existing Monte Carlo models and provide new insights into baryon production mechanisms.

Contribution

It provides the first detailed measurement of angular correlations for identified particles in pp collisions at 7 TeV, highlighting discrepancies with current models for baryon pair correlations.

Findings

Mesons show expected jet-like correlation peaks.

Baryon-baryon pairs exhibit near-side anti-correlations.

Current Monte Carlo models do not reproduce the observed anti-correlation.

Abstract

Two-particle angular correlations were measured in pp collisions at $\sqrt{s} = 7$ TeV for pions, kaons, protons, and lambdas, for all particle/anti-particle combinations in the pair. Data for mesons exhibit an expected peak dominated by effects associated with mini-jets and are well reproduced by general purpose Monte Carlo generators. However, for baryon-baryon and anti-baryon--anti-baryon pairs, where both particles have the same baryon number, a near-side anti-correlation structure is observed instead of a peak. This effect is interpreted in the context of baryon production mechanisms in the fragmentation process. It currently presents a challenge to Monte Carlo models and its origin remains an open question.