LHCb CollaborationAdeva Andany, BernardoDosil Suárez, ÁlvaroFernández Albor, Víctor ManuelGallas Torreira, Abraham AntonioGarcía Pardiñas, JuliánHernando Morata, José ÁngelPlo Casasus, MáximoRomero Vidal, AntonioSaborido Silva, Juan JoséSanmartín Sedes, BraisSantamarina Ríos, CibránVázquez Regueiro, PabloVázquez Sierra, CarlosVieites Díaz, María2020-05-042020-05-042015Aaij, R., Adeva, B., Adinolfi, M. et al. Differential branching fraction and angular analysis of Λ 0b → Λμ+μ− decays. J. High Energ. Phys. 2015, 115 (2015). https://doi.org/10.1007/JHEP06(2015)1151029-8479http://hdl.handle.net/10347/21984The differential branching fraction of the rare decay Λ 0b → Λμ+μ− is measured as a function of q2, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment. Evidence of signal is observed in the q2 region below the square of the J/ψ mass. Integrating over 15 < q2 < 20 GeV2/c4 the differential branching fraction is measured as dB(Λ0b→Λμ+μ−)/dq2=(1.18+0.09−0.08±0.03±0.27)×10−7(GeV2/c4)−1, where the uncertainties are statistical, systematic and due to the normalisation mode, Λ 0b → J/ψΛ, respectively. In the q2 intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon (A ℓFB) and hadron (A hFB) systems are measured for the first time. In the range 15 < q2 < 20 GeV2/c4 they are found to be AℓFB=−0.05±0.09(stat)±0.03(syst)andAhFB=−0.29±0.07(stat)±0.03(syst).eng© CERN, for the benefit of the LHCb Collaboration. Article funded by SCOAP3. This article is distributed under the terms of the Creative CommonsAttribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.https://creativecommons.org/licenses/by/4.0/Rare decayHadron-Hadron ScatteringBranching fractionB physicsFlavour Changing Neutral Currentsjournal article10.1007/JHEP06(2015)115open access