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Probing Hadronic Polarizations with Dilepton Anisotropies

E. L. Bratkovskaya·W. Cassing·U. Mosel
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Abstract

We investigate the production of $e^+e^-$ pairs from $p + Be$ and nucleus-nucleus collisions from 2 GeV/A to 200 GeV/A within a covariant transport approach and focus on the dilepton angular anisotropies as a function of the dilepton invariant mass. Whereas the low mass regime yields information about the Dalitz decays of the $Δ, η$ and $ω$, above M $\approx $0.5 GeV the angular anisotropies provide additional information about the $π^+π^- \to ρ^0 \to e^+e^-$ channel in the medium. The anisotropy coefficient is found to change its sign for M $>$ 0.5 GeV in case of nucleus-nucleus reactions when increasing the bombarding energy from 2 GeV/A to 200 GeV/A which sheds some light on the $ππ\to ρ$ dynamics.

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E. L. Bratkovskaya, W. Cassing, U. Mosel. 1996-05-17. Probing Hadronic Polarizations with Dilepton Anisotropies. https://arxiv.org/abs/nucl-th/9605025

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