Measurement of the ηc(1 S) production cross-section in p p collisions at √s=13TeV
Aaij R., Beteta CA., Ackernley T., Adeva B., Adinolfi M., Afsharnia H., Aidala CA., Aiola S., Ajaltouni Z., Akar S., Albicocco P., Albrecht J., Alessio F., Alexander M., Albero AA., Alkhazov G., Cartelle PA., Alves AA., Amato S., Amhis Y., An L., Anderlini L., Andreassi G., Andreotti M., Archilli F., d’Argent P., Romeu JA., Artamonov A., Artuso M., Arzymatov K., Aslanides E., Atzeni M., Audurier B., Bachmann S., Back JJ., Baker S., Balagura V., Baldini W., Baranov A., Barlow RJ., Barsuk S., Barter W., Bartolini M., Baryshnikov F., Bassi G., Batozskaya V., Batsukh B., Battig A., Battista V., Bay A., Becker M., Bedeschi F., Bediaga I., Beiter A., Bel LJ., Belavin V., Belin S., Beliy N., Bellee V., Belous K., Belyaev I., Ben-Haim E., Bencivenni G., Benson S., Beranek S., Berezhnoy A., Bernet R., Berninghoff D., Bernstein HC., Bertholet E., Bertolin A., Betancourt C., Betti F., Bettler MO., Beuzekom MV., Bezshyiko I., Bhasin S., Bhom J., Bieker MS., Bifani S., Billoir P., Birnkraut A., Bizzeti A., Bjørn M., Blago MP., Blake T., Blanc F., Blusk S., Bobulska D., Bocci V., Garcia OB., Boettcher T., Boldyrev A., Bondar A., Bondar N., Borghi S., Borisyak M., Borsato M., Borsuk JT., Boubdir M.
© 2020, CERN for the benefit of the LHCb collaboration. Using a data sample corresponding to an integrated luminosity of 2.0 fb-1, collected by the LHCb experiment, the production of the ηc(1 S) state in proton–proton collisions at a centre-of-mass energy of s=13TeV 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(1 S) mesons relative to that of the J/ ψ meson is measured using the pp¯ 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(1 S) 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(1 S) and J/ ψ states is measured to be Bb→ηcX/Bb→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(1 S) masses is also determined to be 113.0±0.7±0.1MeV, which is the most precise single measurement of this quantity to date.