Measurement of Υ production in pp collisions at s $$ \sqrt{s} $$ = 5 TeV

Abstract

Abstract

The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at

s

$$ \sqrt{s} $$ = 5 TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb−1 collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ → μ+μ−. Double differential cross-sections times branching fractions, as functions of the transverse momentum pT and the rapidity y of the Υ mesons, are measured in the range pT < 20 GeV/c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are

σ

Υ

1 S

× B

Υ

1 S

→

μ +

μ −

= 2101 ± 33 ± 83

pb ,

σ

Υ

2 S

× B

Υ

2 S

→

μ +

μ −

= 526 ± 20 ± 21

pb ,

σ

Υ

3 S

× B

Υ

3 S

→

μ +

μ −

= 242 ± 16 ± 10

pb ,

$$ \sigma \left(\textrm{Y}(1S)\right)\times \mathcal{B}\left(\textrm{Y}(1S)\to {\mu}^{+}{\mu}^{-}\right)=2101\pm 33\pm 83\ \textrm{pb}, $$$$ \sigma \left(\textrm{Y}(2S)\right)\times \mathcal{B}\left(\textrm{Y}(2S)\to {\mu}^{+}{\mu}^{-}\right)=526\pm 20\pm 21\ \textrm{pb}, $$$$ \sigma \left(\textrm{Y}(3S)\right)\times \mathcal{B}\left(\textrm{Y}(3S)\to {\mu}^{+}{\mu}^{-}\right)=242\pm 16\pm 10\ \textrm{pb}, $$

where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different Υ states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1S) at

s

$$ \sqrt{s} $$ = 5 TeV is updated as well using the directly measured cross-section results from this analysis.