Measurements of the B[superscript +], B[superscript 0], B[0 over s] meson and Λ[0 over b] baryon lifetimes

Abstract

Measurements of b-hadron lifetimes are reported using pp collision data, corresponding to an integrated luminosity of 1.0 fb[superscript −1], collected by the LHCb detector at a centre-of-mass energy of 7 TeV. Using the exclusive decays B [superscript +] → J/ψK [superscript +], B [superscript 0] → J/ψK [superscript ∗](892)[superscript 0], B[superscript 0] → J/ψK[0 over s], J/ψΛ and B[0 over s] the average decay times in these modes are measured to be [superscript T] B[superscript +] → J/ψK[superscript +] = 1.637 ± 0.004 ± 0.003ps, [superscript T] B[superscript 0] → J/ψK[superscript +0] = 1.524 ± 0.006 ± 0.004ps, [superscript T] B[superscript 0] → J/ψK[0 over s] = 1.499 ± 0.013 ± 0.005ps, [superscript T] Λ[0 over b] → J/ψΛ = 1.415 ± 0.027 ± 0.006ps, [superscript T] B[0 over b] → J/ψφ = 1.480 ± 0.011 ± 0.005ps, where the first uncertainty is statistical and the second is systematic. These represent the most precise lifetime measurements in these decay modes. In addition, ratios of these lifetimes, and the ratio of the decay-width difference, ΔΓ [subscript d], to the average width, Γ [subscript d], in the B [superscript 0] system, ΔΓ [subscript d]/Γ [subscript d] = −0.044 ± 0.025 ± 0.011, are reported. All quantities are found to be consistent with Standard Model expectations.