One can see that there are 2 s + 1 possible values of s z. The number " 2 s + 1 " is the multiplicity of the spin system. For example, there are only two possible values for a spin- ⁠ 1 / 2 ⁠ particle: s z = + ⁠ 1 / 2 ⁠ and s z = − ⁠ 1 / 2 ⁠. These correspond to quantum states in which the spin component is pointing in the + z or − z directions respectively, and are often referred to as "spin up" and "spin down". For a spin- ⁠ 3 / 2 ⁠ particle, like a delta baryon, the possible values are + ⁠ 3 / 2 ⁠, + ⁠ 1 / 2 ⁠, − ⁠ 1 / 2 ⁠, − ⁠ 3 / 2 ⁠.