Quantization of Multispinor Fields

The multispinor fields which describe massive fields with spin ≤2 are constructed. These fields are quantized using Schwinger's action principle. Lorentz invariance and physical positive-definiteness requirements are verified. In particular, those fields with spins 0, 1, and ½ are explored in detail. It is shown that the spin-½ system described by a third-rank multispinor is not equivalent to the Dirac field in the presence of electromagnetic interaction. It describes a spin-½ system without intrinsic magnetic moment. The Lorentz invariance of the interacting system is verified. This result will facilitate the physical explanation of the famous $\frac{2}{3}$ ratio of the nucleon magnetic moments.