# Di-electron spectrum at mid-rapidity in $p+p$ collisions at $\sqrt{s} = 200$ GeV

Abstract : 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.
Document type :
Journal articles
Physical Review D, American Physical Society, 2012, 85, pp.092010. <10.1103/PhysRevD.85.092010>

http://hal.in2p3.fr/in2p3-00699504
Contributor : Sylvie Flores <>
Submitted on : Monday, May 21, 2012 - 9:32:17 AM
Last modification on : Monday, May 21, 2012 - 10:46:30 AM

### Citation

L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, et al.. Di-electron spectrum at mid-rapidity in $p+p$ collisions at $\sqrt{s} = 200$ GeV. Physical Review D, American Physical Society, 2012, 85, pp.092010. <10.1103/PhysRevD.85.092010>. <in2p3-00699504>

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