Measurement of the $Λ^0_b\rightarrow J/ψΛ$ angular distribution and the $Λ^0_b$ polarisation in $pp$ collisions

collaboration, LHCb, Aaij, R, Beteta, C Abellán, Ackernley, T, Adeva, B, Adinolfi, M, Afsharnia, H, Aidala, CA, Aiola, S, Ajaltouni, Z
et al (show 909 more authors) (2020) Measurement of the $Λ^0_b\rightarrow J/ψΛ$ angular distribution and the $Λ^0_b$ polarisation in $pp$ collisions. J. High Energ. Phys., 2020. 110 - 110.

This paper presents an analysis of the $\Lambda^0_b\rightarrow J/\psi\Lambda$ angular distribution and the transverse production polarisation of $\Lambda^0_b$ 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 $\Lambda^0_b$ transverse momentum and pseudorapidity of $1 < p_{T} < 20$ GeV$/c$ and $2 < \eta < 5$, respectively. The data are consistent with $\Lambda^0_b$ baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the $\Lambda\rightarrow p\pi^-$ decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES\,III collaboration.