# Reference pp cross-sections for $\Upsilon(1S)$ studies in proton-lead collisions at $\sqrt{s_{NN}} = 5.02$ TeV and comparisons between ALICE and LHCb results

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## Abstract

The ALICE and LHCb collaborations have studied \Y1S production at large rapidities in proton-lead collisions at $\sqrt{s_{ NN}}=5.02\mathrm{ Te V}$\/ at the LHC using di-muon final states. The evaluation of cold nuclear matter effects requires knowledge of the corresponding \Y1S production cross section in $pp$ collisions at the same centre-of-mass energy and in the same kinematic range. In this note the interpolation procedures used to determine this quantity and the related consistency checks are described. Finally, the results from the two experiments on nuclear modification factors are briefly summarized and found to be in good agreement.

 Model predictions for \Y1S production in different rapidity ranges. The relative cross sections normalized to the prediction at $\sqrt{s_{ NN}}=5.02$ TeV are shown. The lines are spline functions through the model points, drawn to guide the eye. The numerical values are given in tables 8, 9, and 10. Fig1a.pdf [7 KiB] HiDef png [204 KiB] Thumbnail [138 KiB] Fig1b.pdf [7 KiB] HiDef png [199 KiB] Thumbnail [135 KiB] Fig1c.pdf [7 KiB] HiDef png [218 KiB] Thumbnail [143 KiB] Comparison of (top left) linear, (top right) power law and (bottom) exponential interpolations for the energy dependence of the \Y1S production cross sections for the theoretical predictions given in Table 9 for the rapidity range $2.5 ## Tables and captions  Existing \Y1S$ pp$cross-section measurements in different rapidity ranges from ALICE and LHCb. The ALICE value, integrated over$ p_{\rm T} <12 {\mathrm{ Ge V /}c} $, is obtained by multiplying the published cross section$\sigma=54.2 \pm 5.0 \pm 6.7$nb by the branching fraction${\rm BF}(\mu^+\mu^-)=2.48\pm 0.05\%$. The LHCb cross sections are integrated over$ p_{\rm T} <15$GeV/$c$\/ and are calculated by integrating the published double differential measurements over the considered rapidity ranges. The first uncertainty is statistical and the second systematic. Table_1.pdf [47 KiB] HiDef png [106 KiB] Thumbnail [57 KiB] tex code Bias and RMS-spread in percent at$\sqrt{s}=5.02$TeV. The interpolation is based on unweighted least squares fits to the predictions at$\sqrt{s}=2.76, 7,\; and\;8$TeV. Table_2.pdf [29 KiB] HiDef png [45 KiB] Thumbnail [25 KiB] tex code Interpolated values of$\sigma(\Y1S)$at$\sqrt{s}=5.02\mathrm{ Te V} $\/ in the range$2.5

Created on 21 October 2019.