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Measurement of the Upsilon Production Cross Section in 920 GeV Fixed-Target Proton-Nucleus Collisions

B Collaboration·I. Abt
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Abstract

The proton-nucleon cross section ratio $R=Br(Υ\to l^+l^-) dσ(Υ)/dy|_{y=0} / {σ(J/ψ)}$ has been measured with the HERA-B spectrometer in fixed-target proton-nucleus collisions at 920 GeV proton beam energy corresponding to a proton-nucleon cms energy of sqrt{s}=41.6 GeV. The combined results for the Upsilon decay channels Upsilon $\to e^+e^-$ and Upsilon $\toμ^+μ^-$ yield a ratio $R=(9.0 \pm 2.1) 10^{-6}$. The corresponding Upsilon production cross section per nucleon at mid-rapidity (y=0) has been determined to be $Br(Υ\to{}l^+l^-) {dσ(Υ)/dy}|_{y=0}= 4.5 \pm 1.1 $ pb/nucleon.

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B Collaboration, I. Abt. 2006-03-08. Measurement of the Upsilon Production Cross Section in 920 GeV Fixed-Target Proton-Nucleus Collisions. https://doi.org/10.1016/j.physletb.2006.04.042

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