It's a task from my studies. I have to calculate the decay rate for muon starting from hamiltonian with current in this form. I've started and ran into troubles.
Could you explain what's the interpretation of a before \gamma^{5} in this current:
J_{\alpha}=\bar{\psi_{e}}\gamma^{\alpha}\left(1-a\gamma^{5}\right)\psi_{\nu_{e}} +\bar{\psi_{\mu}}\gamma^{\alpha}\left(1-a\gamma^{5}\right)\psi_{\nu_{\mu}}?
And will this factor complicate calculations of decay...