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Dilepton anisotropy from $p + Be$ and $Ca + Ca$ collisions at BEVALAC energies

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

A full calculation of lepton-pair angular characteristics is carried out for $e^+e^-$ pairs created in $p + Be$ and $Ca + Ca$ collisions from 1.0 to 2.1 GeV/A. It is demonstrated that the dilepton decay anisotropy depends sensitively on the different sources and may be used for their disentangling. Due to the dominance of the $η$-and $Δ$-Dalitz decays and only a small anisotropy coefficient for $π^+π^-$ annihilation, the expected anisotropy coefficients show a decrease with invariant mass of the dilepton pair and change only moderately when comparing $p + Be$ and $Ca + Ca$ reactions at the same bombarding energy.

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E. L. Bratkovskaya, W. Cassing, U. Mosel. 1996-01-12. Dilepton anisotropy from $p + Be$ and $Ca + Ca$ collisions at BEVALAC energies. https://doi.org/10.1016/0370-2693(96)00302-4

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