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Fragmentation of Two Repelling QCD Strings

by Cody B Duncan and Peter Skands

Submission summary

As Contributors: Cody B Duncan
Preprint link: scipost_202001_00039v1
Date submitted: 2020-01-04
Submitted by: Duncan, Cody B
Submitted to: SciPost Physics
Discipline: Physics
Subject area: High-Energy Physics - Phenomenology
Approach: Phenomenological

Abstract

Motivated by recent discoveries of flow-like effects in pp collisions, and noting that multiple string systems can form and hadronize simultaneously in such collisions, we develop a simple model for the repulsive interaction between two QCD strings with a positive (colour-oriented) overlap in rapidity. The model is formulated in momentum space and is based on a postulate of a constant net transverse momentum being acquired per unit of overlap along a common rapidity direction. To conserve energy, the strings shrink in the longitudinal direction, essentially converting $m^2$ to $p_\perp^2$ for constant $m_\perp^2 = m^2 + p_\perp^2$ for each string. The reduction in $m^2$ implies a reduced overall multiplicity of produced hadrons; the increase in $p_\perp^2$ is local and only affects hadrons in the overlapping region. Starting from the simplest case of two symmetric and parallel strings with massless endpoints, we generalize to progressively more complicated configurations. We present an implementation of this model in the Pythia event generator and use it to illustrate the effects on hadron $p_\perp$ distributions and dihadron azimuthal correlations, contrasting it with the current version of the ``shoving'' model implemented in the same generator.

Current status:
Editor-in-charge assigned


Submission & Refereeing History

Submission scipost_202001_00039v1 on 4 January 2020

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