Rapidity dependence of initial state geometry and momentum correlations in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">p</mml:mi><mml:mo>+</mml:mo><mml:mi>Pb</mml:mi></mml:mrow></mml:math> collisions
Björn Schenke, Sören Schlichting, Pragya Singh
Abstract
Event geometry and initial state correlations have been invoked as possible explanations of long-range azimuthal correlations observed in high-multiplicity $\mathrm{p}+\mathrm{p}$ and $\mathrm{p}+\mathrm{Pb}$ collisions. We study the rapidity dependence of initial state momentum correlations and event-by-event geometry in $\sqrt{s}=5.02\text{ }\text{ }\mathrm{TeV}$ $\mathrm{p}+\mathrm{Pb}$ collisions within the $3+1\mathrm{D}$ IP-Glasma model [B. Schenke and S. Schlichting, Phys. Rev. C 94, 044907 (2016)], where the longitudinal structure is governed by Jalilian-Marian-Iancu-McLerran-Weigert-Leonidov-Kovner rapidity evolution of the incoming nuclear gluon distributions. We find that the event geometry is correlated across large rapidity intervals whereas initial state momentum correlations are relatively short-range in rapidity. Based on our results, we discuss implications for the relevance of both effects in explaining the origin of collective phenomena in small systems.