# Why is the J/$\psi$ suppression enhanced at large transverse energy ?

Abstract : We study the ratio of $J/\psi$ over minimum bias in $Pb$ $Pb$ collisions at SPS energy. The NA50 data exhibit a sharp turn-over at $E_T \sim 100$ GeV (close to the knee of the $E_T$ distribution) followed by a steady, steep decrease at larger $E_T$. We show that this behaviour can be explained by the combined effects of a small decrease of the hadronic $E_T$ in the $J/\psi$ event sample (due to the $E_T$ taken by the $J/\psi$ trigger), together with the sharp decrease of the $E_T$ distributions in this $E_T$ region (tail). This phenomenon does not affect the (true) ratio $J/\psi$ over $DY$ (obtained by the NA50 standard analysis), but does affect the one obtained by the so-called minimum bias analysis. A good agreement is obtained with the data coming from both analysis -- as well as with the ratios of $J/\psi$ and $DY$ over minimum bias -- in the whole $E_{T}$ region.
Document type :
Journal articles

https://hal.archives-ouvertes.fr/hal-00127351
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Submitted on : Monday, January 29, 2007 - 2:53:28 PM
Last modification on : Wednesday, September 16, 2020 - 4:04:42 PM

### Citation

A. Capella, A. B. Kaidalov, D. Sousa. Why is the J/$\psi$ suppression enhanced at large transverse energy ?. Physical Review C, American Physical Society, 2002, 65, pp.054908. ⟨hal-00127351⟩

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