Measurement of the Λb0 → J/ψΛ angular distribution and the Λb0 polarisation in pp collisions
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., Alkhazov G., Alvarez Cartelle P., Alves AA., Amato S., Amhis Y., An L., Anderlini L., Andreassi G., Andreianov A., Andreotti M., Archilli F., Artamonov A., Artuso M., Arzymatov K., Aslanides E., Atzeni M., Audurier B., Bachmann S., Back JJ., Baker S., Balagura V., Baldini W., Baptista Leite J., Barlow RJ., Barsuk S., Barter W., Bartolini M., Baryshnikov F., Basels JM., Bassi G., Batozskaya V., Batsukh B., Battig A., Bay A., Becker M., Bedeschi F., Bediaga I., Beiter A., Belavin V., Belin S., Bellee V., Belous K., Belyaev I., Bencivenni G., Ben-Haim E., Benson S., 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., Bieker MS., Bifani S., Billoir P., Bizzeti A., Bjørn M., Blago MP., Blake T., Blanc F., Blusk S., Bobulska D., Bocci V., Boente Garcia O., Boettcher T., Boldyrev A., Bondar A., Bondar N., Borghi S., Borisyak M., Borsato M., Borsuk JT., Bowcock TJV., Boyer A., Bozzi C., Bradley MJ., Braun S., Brea Rodriguez A., Brodski M.
© 2020, The Author(s). This paper presents an analysis of the Λb0→ J/ψΛ angular distribution and the transverse production polarisation of Λb0 baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb−1, collected with the LHCb experiment. The polarisation is determined in a fiducial region of Λb0 transverse momentum and pseudorapidity of 1 < pT< 20 GeV/c and 2 < η < 5, respectively. The data are consistent with Λb0 baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ− decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration. [Figure not available: see fulltext.]