Measurement of the $\eta_c(1S)$ production cross-section in $pp$ collisions at $\sqrt{s} = 13$ TeV

The LHCb collaboration
Eur.Phys.J.C 80 (2020) 191, 2020.

Abstract (data abstract)
CERN-LHC. Using a data sample corresponding to an integrated luminosity of $2.0\,fb^{-1}$, collected by the LHCb experiment, the production of the $\eta_c(1S)$ state in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13 \text{ TeV}$ is studied in the rapidity range ${2.0 < y < 4.5}$ and in the transverse momentum range ${6.5 < p_{T} < 14.0\text{ GeV}}$. The cross-section for prompt production of $\eta_c(1S)$ mesons relative to that of the ${J/\psi}$ meson is measured using the $p\bar{p}$ decay mode and is found to be ${\sigma_{\eta_c(1S)}/\sigma_{J/\psi} = 1.69 \pm 0.15 \pm 0.10 \pm 0.18}$. The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the ${J/\psi\to p \bar{p}}$ and ${\eta_c\to p \bar{p}}$ decays. The prompt $\eta_c(1S)$ production cross-section is determined to be ${\sigma_{\eta_c(1S)} = 1.26 \pm 0.11\pm 0.08 \pm 0.14 \,\mu b}$, where the last uncertainty includes that on the ${J/\psi}$ meson cross-section. The ratio of the branching fractions of $b$-hadron decays to the $\eta_c(1S)$ and ${J/\psi}$ states is measured to be ${\mathcal{B}_{b\to\eta_c X}/\mathcal{B}_{b\to J/\psi X} = 0.48 \pm 0.03 \pm 0.03 \pm 0.05}$, where the last uncertainty is due to those on the branching fractions of the ${J/\psi \to p \bar{p}}$ and ${\eta_c\to p \bar{p}}$ decays. The difference between the ${J/\psi}$ and $\eta_c(1S)$ masses is also determined to be ${113.0 \pm 0.7 \pm 0.1\text{ MeV}}$, which is the most precise single measurement of this quantity to date.

  • Table 1

    Data from Figure 3 (left); Table 5

    10.17182/hepdata.90457.v1/t1

    Relative $\eta_c$ to $J/\psi$ differential production cross-sections for prompt production. The uncertainties are statistical, systematic, and due to the ${\eta_c\to...

  • Table 2

    Data from Figure 4 (left); Table 6

    10.17182/hepdata.90457.v1/t2

    Differential production cross-sections of $\eta_c$ for prompt production. The uncertainties are statistical, systematic, and due to the $\eta_c\to p \bar{p}$...

  • Table 3

    Data from Figure 3 (right); Table 7

    10.17182/hepdata.90457.v1/t3

    Relative $\eta_c$ to $J/\psi$ differential production cross-sections for production in $b$-hadron inclusive decays. The uncertainties are statistical, systematic, and due...

  • Table 4

    Data from Figure 4 (right); Table 8

    10.17182/hepdata.90457.v1/t4

    Differential production cross-sections of $\eta_c$ for production in $b$-hadron inclusive decays. The uncertainties are statistical, systematic, and due to the...

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