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arXiv · 2405.08094

Possible explanation of the irregular energy dependence of the rapidity width of $\phi$ mesons observed in Pb+Pb collisions

Tom Reichert·Jan Steinheimer·Marcus Bleicher
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Abstract

Experimental data from the NA49 collaboration show an unexpectedly steep rise of the rapidity width of the $\phi$ meson as function of beam energy, which was suggested as possible interesting signal for novel physics. In this work we show that the Ultra-relativistic Quantum-Molecular-Dynamics (UrQMD) model is able to reproduce the shapes of the rapidity distributions of most measured hadrons and predicts a common linear increase of the width for all hadrons. Only when following the exact same analysis technique and experimental acceptance of the NA49 and NA61/SHINE collaborations, we find that the extracted value of the rapidity width of the $\phi$ increases drastically for the highest beam energy. We conclude that the observed steep increase of the $\phi$ rapidity width is a problem of limited detector acceptance and the simplified Gaussian fit approximation.

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Tom Reichert, Jan Steinheimer, Marcus Bleicher. 2024-05-13. Possible explanation of the irregular energy dependence of the rapidity width of $\phi$ mesons observed in Pb+Pb collisions. https://arxiv.org/abs/2405.08094

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