211 articles – 1952 Notices  [english version]
 HAL : in2p3-00699504, version 1
 arXiv : 1204.1890
 Physical Review D 85 (2012) 092010
 Di-electron spectrum at mid-rapidity in $p+p$ collisions at $\sqrt{s} = 200$ GeV
 STAR Collaboration(s)
 (2012)
 We report on mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via $e^{+}e^{-}$ decays, from $\sqrt{s} = 200$ GeV $p+p$ collisions, measured by the large acceptance experiment STAR at RHIC. The ratio of the di-electron continuum to the combinatorial background is larger than 10% over the entire mass range. Simulations of di-electrons from light-meson decays and heavy-flavor decays (charmonium and open charm correlation) are found to describe the data. The extracted $\omega\rightarrow e^{+}e^{-}$ invariant yields are consistent with previous measurements. The mid-rapidity yields ($dN/dy$) of $\phi$ and $J/\psi$ are extracted through their di-electron decay channels and are consistent with the previous measurements of $\phi\rightarrow K^{+}K^{-}$ and $J/\psi\rightarrow e^{+}e^{-}$. Our results suggest a new upper limit of the branching ratio of the $\eta \rightarrow e^{+}e^{-}$ of $1.7\times10^{-5}$ at 90% confidence level.
 Thème(s) : Physique/Physique Nucléaire Expérimentale
 Lien vers le texte intégral : http://fr.arXiv.org/abs/1204.1890
 in2p3-00699504, version 1 http://hal.in2p3.fr/in2p3-00699504 oai:hal.in2p3.fr:in2p3-00699504 Contributeur : Sylvie Florès <> Soumis le : Lundi 21 Mai 2012, 09:32:17 Dernière modification le : Lundi 21 Mai 2012, 10:46:30