In:
The European Physical Journal C, Springer Science and Business Media LLC, Vol. 80, No. 3 ( 2020-03)
Abstract:
Using a data sample corresponding to an integrated luminosity of 2.0 $$\, \text {fb} ^{-1}$$ fb - 1 , collected by the LHCb experiment, the production of the $${\eta _{c}} (1S)$$ η c ( 1 S ) state in proton–proton collisions at a centre-of-mass energy of $$\sqrt{s} =13$$ s = 13 $$\, \text {TeV}$$ TeV is studied in the rapidity range $$2.0 〈 y 〈 4.5$$ 2.0 〈 y 〈 4.5 and in the transverse momentum range $$6.5 〈 p_{\mathrm {T}} 〈 14.0 \, \text {GeV} $$ 6.5 〈 p T 〈 14.0 GeV . The cross-section for prompt production of $${\eta _{c}} (1S)$$ η c ( 1 S ) mesons relative to that of the $${J /\psi }$$ J / ψ meson is measured using the $$p $$ p $$\overline{{p}}$$ p ¯ decay mode and is found to be $${\sigma _{{\eta _{c}} (1S)}/\sigma _{{{J /\psi }}} = 1.69 \pm 0.15 \pm 0.10 \pm 0.18}$$ σ η c ( 1 S ) / σ J / ψ = 1.69 ± 0.15 ± 0.10 ± 0.18 . The quoted uncertainties are, in order, statistical, systematic and due to uncertainties on the branching fractions of the $${{J /\psi }} \!\rightarrow {p} {\overline{{p}}} $$ J / ψ → p p ¯ and $${\eta _{c}} \!\rightarrow {p} {\overline{{p}}} $$ η c → p p ¯ decays. The prompt $${\eta _{c}} (1S)$$ η c ( 1 S ) production cross-section is determined to be $${\sigma _{{\eta _{c}} (1S)} = 1.26 \pm 0.11\pm 0.08\pm 0.14 \,\upmu \text {b}}$$ σ η c ( 1 S ) = 1.26 ± 0.11 ± 0.08 ± 0.14 μ b , where the last uncertainty includes that on the $${J /\psi }$$ J / ψ meson cross-section. The ratio of the branching fractions of $$b $$ b -hadron decays to the $${\eta _{c}} (1S)$$ η c ( 1 S ) and $${J /\psi }$$ J / ψ states is measured to be $${{\mathcal {B}} _{{b} \!\rightarrow {\eta _{c}} X}/{\mathcal {B}} _{{b} \!\rightarrow {{J /\psi }} X} = 0.48 \pm 0.03 \pm 0.03 \pm 0.05}$$ B b → η c X / B b → J / ψ X = 0.48 ± 0.03 ± 0.03 ± 0.05 , where the last uncertainty is due to those on the branching fractions of the $${{J /\psi }} \!\rightarrow {p} {\overline{{p}}} $$ J / ψ → p p ¯ and $${\eta _{c}} \!\rightarrow {p} {\overline{{p}}} $$ η c → p p ¯ decays. The difference between the $${J /\psi }$$ J / ψ and $${\eta _{c}} (1S)$$ η c ( 1 S ) masses is also determined to be $$113.0 \pm 0.7 \pm 0.1 \, \text {MeV} $$ 113.0 ± 0.7 ± 0.1 MeV , which is the most precise single measurement of this quantity to date.
Type of Medium:
Online Resource
ISSN:
1434-6044
,
1434-6052
DOI:
10.1140/epjc/s10052-020-7733-0
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
1397769-6
detail.hit.zdb_id:
1459069-4
