In the QFT Lagrangian, what does the adjoint of $psi$ represent, physically?

Question

In the EM Lagrangian, the QCD Lagrangian, and the charged and neutral weak current Lagrangian, there is always a $psi$ term and its adjoint $bar{psi}$.
The $psi$ term can represent a Dirac spinor for EM, or a Dirac spinor $otimes$ color space for QCD. AFAIK, it represents just a Dirac spinor for the weak currents as well.
My question is, what does the adjoint of $psi$ represent, physically?
Does it represent an anti-particle, a particle creation operator, or something else?

Charles Francis · Accepted Answer

A field operator annihilates a particle, or creates an antiparticle. The adjoint does the opposite, it creates a particle or annihilates an antiparticle.

Vladimir Kalitvianski · Answer

It has largelly the same meaning as the adjoint wave function in the usual QM. $psi$ is a complex function, and one can write two equations for both real and imaginary parts of $psi$, or equivalently two equations for $psi$ and $bar{psi}$.

Answered by Vladimir Kalitvianski on January 1, 2021

In the QFT Lagrangian, what does the adjoint of $psi$ represent, physically?

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