Three-dimensional sizes and shapes of pion emission in heavy-ion collisions

Abstract In the era of precision measurements in high-energy heavy-ion physics, there is an increasing expectation towards phenomenological and theoretical studies to provide a better description of data. In recent years, multiple experiments have confirmed through two-pion Bose–Einstein correlation measurements that the shape of the two-pion pair source can be well described by Lévy-stable distributions. However, direct comparisons of new phenomenological results with the data are still needed to understand the underlying phenomena and learn more about the nature of pion emission. In this paper, we present a three-dimensional analysis of the two-pion source in Monte-Carlo simulations of $$\text {Au}{+}\text {Au}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mtext>Au</mml:mtext> <mml:mo>+</mml:mo> <mml:mtext>Au</mml:mtext> </mml:mrow> </mml:math> collisions at 200 GeV per nucleon collision energy based on EPOS3, and discuss a detailed comparison with the most recent centrality-dependent measurements from the PHENIX Collaboration. We find that the model remarkably agrees with the data for peripheral collisions, while an increasing discrepancy is found in case of central collisions for the source shapes and sizes. On the other hand, scaled correlation strengths are found to be well described by the model across all investigated system sizes.