Measurement of the 𝜂𝑐(1𝑆) production cross-section in 𝑝 𝑝 collisions at 𝑠√=13 TeV

Journal article

Using a data sample corresponding to an integrated luminosity of 2.0 fb−1, collected by the LHCb experiment, the production of the 𝜂𝑐(1𝑆) state in proton–proton collisions at a centre-of-mass energy of 𝑠√=13 TeV is studied in the rapidity range 2.0<𝑦<4.5 and in the transverse momentum range 6.5<𝑝T<14.0GeV. The cross-section for prompt production of 𝜂𝑐(1𝑆) mesons relative to that of the 𝐽/𝜓 meson is measured using the 𝑝 𝑝⎯⎯⎯ decay mode and is found to be 𝜎𝜂𝑐(1𝑆)/𝜎𝐽/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/𝜓→𝑝𝑝⎯⎯⎯ and 𝜂𝑐→𝑝𝑝⎯⎯⎯ decays. The prompt 𝜂𝑐(1𝑆) production cross-section is determined to be 𝜎𝜂𝑐(1𝑆)=1.26±0.11±0.08±0.14μb, where the last uncertainty includes that on the 𝐽/𝜓 meson cross-section. The ratio of the branching fractions of 𝑏-hadron decays to the 𝜂𝑐(1𝑆) and 𝐽/𝜓 states is measured to be 𝑏→𝜂𝑐𝑋/𝑏→𝐽/𝜓𝑋=0.48±0.03±0.03±0.05, where the last uncertainty is due to those on the branching fractions of the 𝐽/𝜓→𝑝𝑝⎯⎯⎯ and 𝜂𝑐→𝑝𝑝⎯⎯⎯ decays. The difference between the 𝐽/𝜓 and 𝜂𝑐(1𝑆) masses is also determined to be 113.0±0.7±0.1MeV, which is the most precise single measurement of this quantity to date.

Authors: Aaij, R; Beteta, CA; Ackernley, T; Bjørn, M; Fischer, KM

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer Nature
• Journal: European Physical Journal C
• Volume: 80
• Issue: 3
• Article number: 191
• Publication date: 2020-03-02
• Acceptance date: 2020-02-09
• DOI: 10.1140/epjc/s10052-020-7733-0
• EISSN: 1434-6052
• ISSN: 1434-6044
• Language: English
• Keywords: FFR