A particular representation of gamma matrices

[array89]

I was wondering if there is a representation of gamma matrices unitarily equivalent to the standard representation for which Dirac Spinors with positiv energy and generic momentum have only the first two component different prom zero. Anyone can help me?

 

[olgranpappy]

I was wondering if there is a representation of gamma matrices unitarily equivalent to the standard representation...

yeah, presumably there are lots of representations which are unitarily equivalent to the standard representation... I'm not sure what you are asking? As far as I know unitary equivalence means a matrix A is related to another matrix B via A=UBU^\dagger where U is unitary. So take any unitary matrix U and apply U\gamma_\mu U^\dagger for each mu to generate an equivalent rep.

 

[array89]

yes I know it. I was wondering what's the representation for which any spinor of positive energy and momentum p have only the first two component different from zero

 

[DrDu]

Isn't that the definition of the Foldy Wouthuysen transformation?