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Angular distribution of $J/ψ$ decays in dimuon channel in 800 GeV proton-copper collisions

Ting-Hua Chang
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Abstract

The anuglar distribution of $J/ψ$ decays in the $μ^{+}μ^{-}$ channel in 800 proton-copper collisions has been measured for $x_F$ > 0.25. The polarization parameter $λ$ is extracted in 1 GeV of $p_T$ and 0.1 of $x_F$ bins for two magnet configugrations with different acceptances. The data indicate that the $J/ψ$'s are produced with a slight transverse polarization at small $x_F$, which turns to longitudinal at $x_F$ > 0.6. No $p_T$ dependence of $λ$ is observed. Theoretical calculations are needed in order to interpret the measurements.

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Ting-Hua Chang. 2000-12-13. Angular distribution of $J/ψ$ decays in dimuon channel in 800 GeV proton-copper collisions. https://arxiv.org/abs/hep-ex/0012034

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