在粒子物理中，Λ粒子是一类由三个夸克组成的重子。一个上夸克、一个下夸克和一个奇夸克组成Λ0；一个上夸克、一个下夸克和一个粲夸克组成Λ+
c；一个上夸克、一个下夸克和一个底夸克组成Λ0
b。Λ0于1947年的一次宇宙射线相互作用中首先被发现。该粒子理论寿命为约10 s，但它实际存留了约10 s。使它存留了如此长时间的未知属性后来被称为奇异性，Λ粒子的“奇异性”（strangeness）也导致了奇夸克的发现和奇异性守恒定律这一理论的创造。该理论指出，如果某些质量较小的粒子表现出“奇异性”，它们的半衰期便会较长（因为在重子的衰变非弱相互作用力衰变过程中奇异性必须守恒）。

The Lambda baryons are a family of subatomic hadron particles that have the symbols Λ0, Λ+
c, Λ0
b, and Λ+
t and have +1 elementary charge or are neutral. They are baryons containing three different quarks: one up, one down, and one third quark, which can be a strange (Λ0), a charm (Λ+
c), a bottom (Λ0
b), or a top (Λ+
t) quark. The top Lambda is not expected to be observed as the Standard Model predicts the mean lifetime of top quarks to be roughly 6975500000000000000♠5×10 s. This is about one-twentieth the timescale for strong interactions, and, therefore it does not form hadrons.