2 Search Results

A sample of 𝑝⁢𝑝 collision data, corresponding to an integrated luminosity of 5.4 fb⁻¹ and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the $$Ξ^0_b$$ baryon to that of the $$Λ^0_b$$ baryon, 𝑟_𝜏 $$≡$$ $$𝜏_{Ξ^0_b}$$$$/𝜏_{Λ^0_b}$$. The value 𝑟$$^{\textrm{Run 2}}_𝜏$$ =1.004 ± 0.009 ± 0.006 is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain 𝑟_𝜏 =1.004 ± 0.008 ± 0.005. Multiplying by the known value of the $$Λ^0_b$$ lifetime yields $$𝜏_{Ξ^0_b}$$ = 1.475 ±more » 0.012 ± 0.008 ± 0.009 ps, where the last uncertainty is due to the limited knowledge of the $$Λ^0_b$$ lifetime. This measurement improves the precision of the current world average of the $$Ξ^0_b$$ lifetime by about a factor of two, and is in good agreement with the most recent theoretical predictions.« less

The first measurement of the $CP$ asymmetry of the decay rate ( $A_{CP}$ ) and the $CP$ average ( $\mathrm{\Sigma }{A}_{\mathrm{FB}}$ ) and $CP$ asymmetry ( $\mathrm{\Delta }{A}_{\mathrm{FB}}$ ) of the forward-backward asymmetry in the muon system of ${\mathrm{\Lambda }}_c^{+}\to p{\mu }^{+}{\mu }^{-}$ decays is reported. The measurement is performed using a data sample of proton-proton collisions, recordedmore » by the LHCb experiment from 2016 to 2018 at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$ . The asymmetries are measured in two regions of dimuon mass near the  $\varphi$ -meson mass peak. The dimuon-mass integrated results are $A_{CP}=(-1.1\pm 4.0\pm 0.5)\%$ , $\mathrm{\Sigma }{A}_{\mathrm{FB}}=(3.9\pm 4.0\pm 0.6)\%$ , $\mathrm{\Delta }{A}_{\mathrm{FB}}=(3.1\pm 4.0\pm 0.4)\%$ , where the first uncertainty is statistical and the second systematic. The results are consistent with the conservation of $CP$ symmetry and the Standard Model expectations. © 2025 CERN, for the LHCb Collaboration 2025 CERN« less