We report on mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via e+e−e^{+}e^{-}e+e− decays, from s=200sqrt{s} = 200s =200 GeV p+pp+pp+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 ω→e+e−omega ightarrow e^{+}e^{-}ω→e+e− invariant yields are consistent with previous measurements. The mid-rapidity yields (dN/dydN/dydN/dy) of ϕphiϕ and J/ψJ/psiJ/ψ are extracted through their di-electron decay channels and are consistent with the previous measurements of ϕ→K+K−phi ightarrow K^{+}K^{-}ϕ→K+K− and J/ψ→e+e−J/psi ightarrow e^{+}e^{-}J/ψ→e+e−. Our results suggest a new upper limit of the branching ratio of the η→e+e−eta ightarrow e^{+}e^{-}η→e+e− of 1.7×10−51.7 imes10^{-5}1.7×10−5 at 90% confidence level.
Di-electron spectrum at mid-rapidity in p+p collisions at root s=200 GeV
Fazio, S.Membro del Collaboration Group
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2012-01-01
Abstract
We report on mid-rapidity mass spectrum of di-electrons and cross sections of pseudoscalar and vector mesons via e+e−e^{+}e^{-}e+e− decays, from s=200sqrt{s} = 200s =200 GeV p+pp+pp+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 ω→e+e−omega ightarrow e^{+}e^{-}ω→e+e− invariant yields are consistent with previous measurements. The mid-rapidity yields (dN/dydN/dydN/dy) of ϕphiϕ and J/ψJ/psiJ/ψ are extracted through their di-electron decay channels and are consistent with the previous measurements of ϕ→K+K−phi ightarrow K^{+}K^{-}ϕ→K+K− and J/ψ→e+e−J/psi ightarrow e^{+}e^{-}J/ψ→e+e−. Our results suggest a new upper limit of the branching ratio of the η→e+e−eta ightarrow e^{+}e^{-}η→e+e− of 1.7×10−51.7 imes10^{-5}1.7×10−5 at 90% confidence level.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.