Effects of Overlapping Strings in pp Collisions

TL;DR

This paper investigates how overlapping strings in high-energy proton-proton collisions can fuse or recombine, affecting particle production, and introduces models implemented in a simulation that better match experimental data.

Contribution

It presents new models for string interactions in pp collisions, including fusion and recombination, implemented in a Monte Carlo generator to improve data agreement.

Findings

Enhanced baryon and strangeness production in models

Improved fit to identified particle spectra

Potential implications for understanding high-energy collision dynamics

Abstract

In models for hadron collisions based on string hadronization, the strings are usually treated as independent, allowing no interaction between the confined colour fields. In studies of nucleus collisions it has been suggested that strings close in space can fuse to form "colour ropes". Such ropes are expected to give more strange particles and baryons, which also has been suggested as a signal for plasma formation. Overlapping strings can also be expected in pp collisions, where usually no phase transition is expected. In particular at the high LHC energies the expected density of strings is quite high. To investigate possible effects of rope formation, we present a model in which strings are allowed to combine into higher multiplets, giving rise to increased production of baryons and strangeness, or recombine into singlet structures and vanish. Also a crude model for strings recombining into junction structures is considered, again giving rise to increased baryon production. The models are implemented in the DIPSY MC event generator, using PYTHIA 8 for hadronization, and comparison to pp minimum bias data, reveals improvement in the description of identified particle spectra.