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

Abstract

The proton-nucleon cross section ratio $R=Br({\rm Y}\to l^{+}{l}^{-})d\sigma ({\rm Y})/dy{|}_{y=0}/\sigma (J/\psi )$ 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 $\to {\mu }^{+}{\mu }^{-}$ 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 $Br({\rm Y}\to l^{+}{l}^{-})d\sigma ({\rm Y})/dy{|}_{y=0}=4.5\pm 1.1$ pb/nucleon.

17 pages, 7 figures

Cited by in corpus (4)

• Collider Physics at HERA
• Measurement of D^0, D^+, D_s^+ and D^{*+} Production in Fixed Target 920 GeV Proton-Nucleus Collisions
• Calibration of the mirror system in the HERA-B RICH
• Nuclear Medium Effects in $J/\Psi$ Production at HERA-B