2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185087We give an update on the lifetime difference of $B_s$ mesons which accounts for recent lattice bag parameter results, and obtain $(ΔΓ/Γ)_{B_s}=(9.3^{+3.4}_{-4.6})%$. We then review the current theoretical uncertainties and conclude with a pessimistic perspective on further improvements.7 pages, Talk presented at the UK Phenomenology Workshop on Heavy Flavour and CP Violation, 17 - 22 September 2000, St John's College, Durham. Reference correctedHigh Energy Physics - Phenomenologytext