The Delta Baryon

重子Delta

Particle 质点	Symbol 符号	Makeup 组成	Rest mass MeV/c² 静止质量 MeV/c²	Q	Spin 自旋	I₃	B	S	Lifetime (seconds> 寿命（秒）	Decay Modes 衰变模式
Delta Δ粒子	Δ⁺⁺	uuu uuu（专名或术语）	1232	+2	3/2	3/2	+1	0	0.56x10^-23	pπ⁺
Delta Δ粒子	Δ⁺	uud uud（专名或术语）	1232	+1	3/2	1/2	+1	0	0.56 x10^-23	pπ⁰
Delta Δ粒子	Δ⁰	udd udd（专名或术语）	1232	0	3/2	-1/2	+1	0	0.56 x10^-23	nπ⁰
Delta Δ粒子	Δ^-	ddd ddd（专名或术语）	1232	-1	3/2	-3/2	+1	0	0.56 x10^-23	nπ^-

Q=charge, I₃= Isospin projection, B=Baryon number, S = Strangeness

The delta is a baryon which contains only up and down quarks. The Δ⁺ and Δ⁰ have the same quark compositions as the proton and neutron respectively and decay quickly by the strong interaction to the proton and neutron and a π⁰. If such a decay pathway is available to a particle, it decays very quickly - on the order of 10^-23 seconds. Another example is the decay Δ⁰ --> p⁺ + π^-. Note that the delta baryon Δ⁰ has the same quark makeup as the neutron, but its mass is much larger. Its mass is sufficient for this decay to be energetically favorable. The four varieties have similar masses and are said to be an isospin quartet with isospin 3/2.

delta 是一种重子，其内部仅包含上夸克和下夸克。Δ⁺和Δ⁰的夸克组成分别与质子和中子相同，并通过强相互作用迅速衰变成质子、中子和π⁰。如果某种粒子能够通过强相互作用衰变，它会非常迅速地衰变——大约在10⁻²³秒的量级。另一个例子是Δ⁰ → p⁺ + π⁻的衰变。注意，delta重子Δ⁰的夸克组成与中子相同，但其质量要大得多。其质量足以使这种衰变在能量上是有利的。这四种粒子具有相似的质量，并被称作同位旋四重态，同位旋为3/2。

Q=电荷，I₃=同位旋投影，B=重子数，S= strangeness