- #1
anthony2005
- 25
- 0
The pion decay constant [itex]f_{\pi}[/itex] is defined by
[tex]<0|\overline{d}\gamma^{0}\gamma^{5}u|\pi^{+}>=f_{\pi}m_{\pi}[/tex]
where I have set the momentum [itex]\boldsymbol{p}=0[/itex] (and used the temporal component of the axial vector).
Now, at the right-hand-side the dimension is two (the decay constant and the mass are measured in MeV). At the left-hand side, each quark carries dimension 3/2, so the whole axial vector has dimensions 3.
The dimensions do not match! Where is the problem?
[tex]<0|\overline{d}\gamma^{0}\gamma^{5}u|\pi^{+}>=f_{\pi}m_{\pi}[/tex]
where I have set the momentum [itex]\boldsymbol{p}=0[/itex] (and used the temporal component of the axial vector).
Now, at the right-hand-side the dimension is two (the decay constant and the mass are measured in MeV). At the left-hand side, each quark carries dimension 3/2, so the whole axial vector has dimensions 3.
The dimensions do not match! Where is the problem?