lambda particle

noun Physics.

1. any of a family of neutral baryons with strangeness −1 or charm +1, and isotopic spin 0. The least massive member of the lambda family was the first strange particle to be discovered. Symbol: Λ

1. An electrically neutral baryon having a mass 2,183 times that of the electron and a mean lifetime of approximately 2.6 X 10-10 seconds. See Table at subatomic particle.