# Measurement of $\Upsilon$ production in $pp$ collisions at $\sqrt{s}=2.76$ TeV

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## Abstract

The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 pb^{-1} collected in proton-proton collisions at a centre-of-mass energy of sqrt{s}=2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the Upsilon transverse momentum and rapidity, over the ranges p_T<15 GeV/c and 2.0<y<4.5. The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S) -> mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S) -> mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic.

 Invariant mass distribution of selected $\Upsilon \rightarrow \mu ^+\mu ^-$ candidates with $p_{\rm T} <15 {\mathrm{ Ge V /}c}$ and $2.0 ## Tables and captions  Relative systematic uncertainties (in$\%$) affecting the \Upsilon production cross-section measurements in the full kinematic region. The total uncertainties are obtained by adding the individual effects in quadrature. Table_1.pdf [33 KiB] HiDef png [83 KiB] Thumbnail [40 KiB] tex code Cross-sections for$\Upsilon(1\mathrm{S})$,$\Upsilon(2\mathrm{S})$and$\Upsilon(3\mathrm{S})$mesons times dimuon branching fractions (in$\rm nb$) in bins of$p_{\rm T}$and$y$without normalisation to the bin sizes. The first uncertainty is statistical and the second is systematic. Table_2.pdf [43 KiB] HiDef png [180 KiB] Thumbnail [80 KiB] tex code Ratios of the$\Upsilon(2\mathrm{S}) $to$\Upsilon(1\mathrm{S}) $and$\Upsilon(3\mathrm{S}) $to$\Upsilon(1\mathrm{S}) $cross-sections times dimuon branching fractions as functions of$p_{\rm T}$and$y\$. The first uncertainty is statistical and the second is systematic. Table_3.pdf [43 KiB] HiDef png [142 KiB] Thumbnail [74 KiB] tex code

Created on 21 October 2019.