LHCb CollaborationAdeva Andany, BernardoBorsato, MartinoChobanova, VeronikaCid Vidal, XabierDosil Suárez, ÁlvaroFernández Albor, Víctor ManuelGallas Torreira, Abraham AntonioGarcía Pardiñas, JuliánHernando Morata, José ÁngelLemos Cid, EdgarLucio Martínez, MiriamMartínez Santos, DiegoPlo Casasus, MáximoPrisciandaro, JessicaRamos Pernas, MiguelRomero Vidal, AntonioSaborido Silva, Juan JoséSanmartín Sedes, BraisSantamarina Ríos, CibránVázquez Regueiro, PabloVieites Díaz, MaríaVázquez Sierra, Carlos2020-05-202020-05-202017Aaij, R., Adeva, B., Adinolfi, M., Ajaltouni, Z., Akar, S., Albrecht, J., ... & Cartelle, P. A. (2017). Observation of ηc(2S) →pp¯ and search for X(3872) →pp¯ decays. Physics Letters B, 769, 305-3130370-2693http://hdl.handle.net/10347/22483The first observation of the decay ηc(2S) →pp¯ pis reported using proton–proton collision data corre-sponding to an integrated luminosity of 3.0fb−1recorded by the LHCb experiment at centre-of-mass energies of7 and 8TeV. The ηc(2S)resonance is produced in the decay B+→[c¯ c]K+. The product of branching fractions normalised to that for the J/ψintermediate state, Rηc(2S), is measured to be Rηc (2S) ≡ B(B+→ηc(2S)K+ )×B(ηc(2S)→ p¯p ) B(B+→ J/ψ K+)×B( J/ψ → p¯p ) = (1.58±0.33±0.09)×10−2, where the first uncertainty is statistical and the second systematic. No signals for the decays B+→X(3872)(→p¯ p)K+and B+→ψ(3770)(→p¯ p)K+are seen, and the 95% confidence level upper limits on their relative branching ratios are found to be RX(3872)<0.25 ×10−2and Rψ(3770)<0.10. In addition, the mass differences between the ηc(1S)and the J/ψstates, between the ηc(2S)and the ψ(2S)states, and the natural width of the ηc(1S)are measured as M J/ψ − Mηc (1S) = 110.2±0.5 ±0.9MeV, Mψ(2S) − Mηc (2S) = 52.5±1.7±0.6MeV, ηc (1S) = 34.0±1.9±1.3MeV.eng©2017 Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.http://creativecommons.org/licenses/by/4.0/journal article10.1016/j.physletb.2017.03.0461873-2445open access