Final answer:
Strange quarks are 'unusually long lived' due to their decay by the weak force instead of the strong force, and because strangeness is conserved in strong and electromagnetic interactions but not in weak interactions, leading to slower decay processes.
Step-by-step explanation:
Strange quarks are considered 'unusually long lived' because their decay is not governed by the strong force, but rather by the weak force. Hadrons containing strange quarks decay via the weak interaction, which takes considerably more time than the strong interaction that typically governs hadronic reactions. The conservation laws also behave differently with strange quarks; while strangeness is conserved in strong and electromagnetic interactions, it is not conserved in weak interactions. This selective conservation is a key factor contributing to the increased lifetime of particles containing strange quarks, as their decay processes -- which do not conserve strangeness -- can only occur via the slow-acting weak force.
Through accelerator experiments, it's observed that the production lifetimes of particles like Λ, Σ, and Ξ are on the order of 10-10 seconds, much longer than expected were they to decay by the strong force. This suggests the operation of the weak force in such decays, leading to the conclusion that particles with strangeness decay more slowly.