Comments on spin operators and spin-polarization states of 2 + 1 fermions
Departamento Física e Química, UNESP, Campus de Guaratinguetá, Brazil
2 Instituto de Física, Universidade de São Paulo, Caixa Postal 66318-CEP, 05315-970, São Paulo, S.P., Brazil
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In this brief article we discuss spin-polarization operators and spin-polarization states of 2 + 1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2 + 1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2 + 1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.
© Springer-Verlag, 2005