Study of Bs0 → J/ψπ+π−K+K− decays
Aaij R., Abellán Beteta C., Ackernley T., Adeva B., Adinolfi M., Afsharnia H., Aidala CA., Aiola S., Ajaltouni Z., Akar S., Albrecht J., Alessio F., Alexander M., Alfonso Albero A., Aliouche Z., Alkhazov G., Alvarez Cartelle P., Amato S., Amhis Y., An L., Anderlini L., Andreianov A., Andreotti M., Archilli F., Artamonov A., Artuso M., Arzymatov K., Aslanides E., Atzeni M., Audurier B., Bachmann S., Bachmayer M., Back JJ., Baker S., Baladron Rodriguez P., Balagura V., Baldini W., Baptista Leite J., Barlow RJ., Barsuk S., Barter W., Bartolini M., Baryshnikov F., Basels JM., Bassi G., Batsukh B., Battig A., Bay A., Becker M., Bedeschi F., Bediaga I., Beiter A., Belavin V., Belin S., Bellee V., Belous K., Belov I., Belyaev I., Bencivenni G., Ben-Haim E., Berezhnoy A., Bernet R., Berninghoff D., Bernstein HC., Bertella C., Bertholet E., Bertolin A., Betancourt C., Betti F., Bettler MO., Bezshyiko I., Bhasin S., Bhom J., Bian L., Bieker MS., Bifani S., Billoir P., Birch M., Bishop FCR., Bizzeti A., Bjørn M., Blago MP., Blake T., Blanc F., Blusk S., Bobulska D., Boelhauve JA., Boente Garcia O., Boettcher T., Boldyrev A., Bondar A., Bondar N., Borghi S., Borisyak M., Borsato M., Borsuk JT., Bouchiba SA., Bowcock TJV., Boyer A., Bozzi C.
© 2021, The Author(s). The decays Bs0 → J/ψπ+π−K+K− are studied using a data set corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The decays Bs0 → J / ψK∗ 0K ¯ ∗ 0 and Bs0 → χc1(3872)K+K−, where the K+K−pair does not originate from a ϕ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate χc1(3872)ϕ, J / ψK∗ 0K ¯ ∗ 0, ψ(2S)ϕ and χc1(3872)K+K− states are reported. A structure, denoted as X(4740), is observed in the J/ψϕ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be mX(4740)=4741±6±6MeV/c2,ΓX(4740)=53±15±11MeV, where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the Bs0 meson is performed and gives a value of mBs0=5366.98±0.07±0.13MeV/c2. [Figure not available: see fulltext.]